DOCUMENT RESUME ED 129 585 SE 021 157 TITLE Introduction to Sonar, Naval Education and Irainin(; Command. Revised Edition. INSTITUTION Naval Education and Training Command, Pensacola, Fla. REPORT NO NAVEDTRA-10130-C PUB DATE 76 NOTE 223p.; Photographs and shaded figures may not reproduce well AVAILABLE FROM Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402 (Stock Number 0502-LP-050-6510; No price quoted) EDRS PRICE MF-$0.83 HC-$12.71 Plus Postage. DESCRIPTORS Acoustics; *Inservice Education; *InLicructional Ni..terials; *Marine Technicians; Military Personnel; Military Training; *Physics; Science Education; *Technical Education; Textbooks IDENTIFIERS *Navy; *Sonar

ABSTRACT This Rate Training Manual (FTM) and Nonresident Career Course form a self-study package for those U.S. Navy personnel who are seeking advancement in the Sonar Technician Rating. Among the requirements of the rating are the abilities to obtain and interpret underwater data, operate and maintain upkeep of sonar equipment, and interpret target and oceonographic data. Designed for individual study and not formal classroom instruction, this book provides subject matter that relates directly to the occupational qualifications of the Sonar Technician Rating. Included in the book are chapters on the physics of sound, the bathythermograph, principles of sonar, basic fire control, test equipment and methods, and security. (Author/MH)

*********************************************************************** Documents acquired by ERIC include many informal unpublished *materials not available from other sources. ERIC makes every effort* *to obtain the best copy available. Nevertheless, items of marginal *reproducibility are often encountered and this affects the quality *of the microfiche and hardcopy reproductions ERIC makes available *via the ERIC Document Reproduction Service (EDRS). EDPS is not At *responsible for the quality of the original document. Reproductions* *supplied by EDRS are the best that can be made from the original. *********************************************************************** Cr.-

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N AND TRAINING COMMAND , . , TRAINING MANUAL 1. SIDENT CAREER COURSE

EDTRA 10130-C

7. PREFACE

This Rate Training Manual and Nonresident CareerCourse (RTM/NRCC) form a self-study package for those personnelwho are seeking advancement in the Sonar Technician Rating. This package willenable these personnel to helpthemselvesfulfillthe requirements of the rating. Among these requirements are the abilities to obtain and interpretunderwater data for operational use; operate and maintain upkeep ofsonar equipment; perform as a member of an antisubmarine (A/S) attack team; interprettarget and oceanogaphic data; perform intermediate maintenanceon sonar and allied equipment; and to work with records andreports associated with sonar operations. Designed for individual study and not formalclassroom instruction, the RTM provides subject matter that relatesdirectly to the occupational qualifications of the Sonar Technician Rating. The NRCC provides the usualway of satisfying the requirements for completing the RTM. The set of assignments inthe NRCC includes learning objectives and supporting items designed to lead studentsthrough the RTM. This training manual and nonresidentcareer course was prepared by the Naval Education and Training ProgramDevelopment Center, Pensacola, Florida, for the Chief of Naval Education andTraining. Technical assistance was provided by Fleet Antisubmarine Warfare Training Center Pacific,San Diego, California; Naval Submarine School, Groton,Connecticut; Naval Underwater Sound Lab, New London, Connecticut; andNaval Intelligence Support Center, Washington, D.C.

Revised 1976 Stock Ordering No. 0502-LP-050-6510

Published by NAVAL EDUCATION AND TRAINING SUPPORTCOMMAND

UNITED STATES GOVERNMENT PRINTING OFFICE WASHINGTON, D.C.: 1976

3 THE UNITED STATES NAVY

GUARDIAN OF OUR COUNTRY The United States Navy is responsible for maintaining control of the sea and is a ready force on watch at home and overseas, capable of strong action to preserve the peace or of instant offensive action to win in war. It is upon the maintenance of this control that our country's glorious future depends; the United States Navy exists to make it so.

WE SERVE WITH HONOR Tradition, valor, and victory are the Navy's heritage from the past. To these may be added dedication, disciphne, and vigilance as the watchwords of the present and the future. At home or on distant stations we serve with pride, confident in the respect of our country, our shipmates, and our families. Our responsibilities sober us; our adversities strengthen us. Service to God and Country is our special privilege. We serve with honor.

THE FUTURE OF THE NAVY The Navy will always employ new weapons, new techniques, and greater power to protect and defend the United States on the sea, under the sea, and in the air. Now and in the future, control of the sea gives the United States her greatest advantage for the maintenance of peace and for victory in war. Mobility, surprise, dispersal, and offensive power are the keynotes of the new Navy. The roots of the Navy lie in a strong belief in the future, in continued dedication to our tasks, and in reflection on our heritage from the past. Never have our opportunities and our responsibilities been greater.

li CONTENTS

CHAPTER Page The Sonar Technician 1

2. History and Development of ASW 15

3. Physics of Sound 35

4. Bathythermograph 58

5. Bearings and Motion 71

6. Principles of Sonar 85

7. Basic Fire Control 109

8. Con .munications 127

9. Test Equipment; Test Methods; Maintenance 141

10. Security 162 APPENDIX

1.Glossary 173

1NDEX 178

Occupational Standards 185 Nol.c.esident Career Course Follows OccupationalStandards

5

III CHAPTER 1

THE SONAR TECHNICIAN

A substantialforce of conventionalind (as applicable), and associatedgear. They musi nuclear-poweredsubmarines, many of them also be able to perform both operational and capable of launching nuclear missiles, represents preventive maintenance on the equipment they a potential threat to our country's security and a operate. This training manual is designed to heir continuingchallengetoourNavy's you meet theprofessional qualificationsfor antisubmarine forces. advancement to Third Class Sonar Technician. To meet this challenge. U.S. Navy ships and The most sensible approach toyour studies is to submarinescontinuallyconductexercisesin first understand the general makeup ofthe text. antisub marinewarfare (ASW ) operations, This book is a self-study manual writtento help revising tactics and evaluating new methods and you become a Sonar Technician with the least equipment used for detecting and destroying possible outside assistance. To aidyou in this enemy underwater craft.Destroyers.frigates, respect, chapters with related subject matterare and cruisers are our main antisubmarine (A/S) grouped together to make studying easier. surface vessels. They provide protection against Even though there always is the temptation submarines for major surface ships by forminga to skip the front matter of a book andgct on sonar screen around the ship. Upon detection of with studying the text, this practice isa costly a submarine trying to penetrate the screen. the shortcut and should be avoided. Ifyou skimmed A/S vessel initiates an attack, and themain body through the front matter of this trainingmanual turns away from the contact area. Ourown to get on to chapter I. go back, now read that submarinesparticularly nuclear-powered types material. witht heirgenerallysuperiordetection The table of contents givesyou an overall equipmentplay an equally important role is picture of the subject matter coveredin this ASW. They are capable of selecting the depth manual. By using it, you can locatea general thatprovides thebest underwater detection subject, such as underwater sound equipment co nd i t io ns. Additionally.theyhavethe for submarine detection and navigation.The enduranceto conduct surveillance operations preface tells you the purpose of themanual, over wide ocean areas. who wroteit,and who providedtechnical The SonarTechnicianwhetheron a assistance. submarine or a surface shipis an indispensable While you are studying this manual,you will contributor to our nation's defense. The primary findthe indexatthe back of the booka taskofallsonar personnelistoprovide time-saving reference. By checking theindex, underwater data for operational use. you can locate specific data abouta particular In to relation thattask.several sonar set or piece of sonar equipment. Itis responsibilities are applicable to all branches of actually an alphabetical list of the important the rating. All Sonar Technicians must be able to points or keywords in this book,along with the operate the sonar equipment installed on their page(s) where each subject is discussed. particularships.Thisresponsibilityincludes Each chapter has been preparedto satisfy manipulation and interpretation of data derived the latest change in the Manual of NaryEnlisted from sonar equipment. fire control equipment Manpower and Persomzel Classificationsand

6 INTRODUCTION TOSONAR

Inust cases will belimited to the sonar gang()t- Occvnational Standards,NAVPERS 18008-D, surface ASW shipsuchasa occupational (professional) anoperating .and covers only the destroyer. qualifications, not the militaryrequirements. chaptergives Theremainderofthis Submarine Sonar Technician(STS) information calculated tohelp you in working that for advancement. Itis highly recommended 'Fire Submarine SonarTechnician operates this chapter carefullybefore you He must be able to you study the installed sonar equipment. begin intensive studyot' the remainder of manipulate, control, evaluate.and interpret data manual. derived from submarinepassive and active sonar equipment,oceanographicequipment,and associated submarine auxiliarysonar equipment. ENLISTED RATINGSTRUCTURE He also must be able toperform organizational submarine rating structure, two andintermediate maintenance on Withintheenlisted sonar and alliedequipments. As STS 3 or2, ratingsgeneral andserviceare of will be limited to the types of applicable to your billets in most cases concern to you.These ratings are sonar gang of anoperating submarine. both the Regular Navyand Naval Reserve. GENERAL RATINGSidentifybroad dutiesand occupationalfieldsofrelated RESPONSIBILITIES ratings include service REWARDS AND functions. Some general OF ADVANCEMENT ratings; others do not. identify subdivisions SERVICE RATINGS Advancementbringsbothincreased or specialitieswithin a general rating.Although rewards.You at any pettyofficer responsibilitiesandincreased service ratings can exist should start looking alitadand considering the level, they are most commonat the P03 and while you March 1975, the ST rating responsibilities and rewards right now P02 levels. As of I E-8. are preparingfor advancement. was split intoservice ratings up through By now, you shouldbe aware of many of the advantages ofadvancement: higher pay, interesting and challenging SONAR TECHNICIANRATING greater prestige, more work, and the satisfactionof getting ahead in Navy ratings are dividedinto 12 groups, with your chosen career.You will also discover that the ratings in each groupbeing occupationally oneofthemostenduringrewardsof related. Sonar Technicianis a general rating in advancementisthe personal satisfaction you group I. calledthe deck group.Following is an findin developing your skillsand increasing outline of the tasksapplicable to the divisionsof your knowledge. rating at the second and The Navy also benefits by youradvancement the Sonar Technician essential to third class levels. since highly trained personnel are the functioning of theNavy. Each advancement Navy in two ways. (STG) increases your value to the Surface Sonar Technician First. you become morevaluable as a technical your own rating.Second, you Technicianoperates specialistin TheSurfaceSonar become more valuableasa man who can installed sonar equipment.He must be able to others and thus make and interpret data supervise, lead, and train manipulate, control. evaluate, far-reaching and long-lastingcontributions to the derived from surfacepassive and active sonar oceanographicequipment, Navy. equipment, equipment, associatedsurface auxiliary sonar LEADERSHIP RESPONSIBILITIES and surface fire controlequipment. He also must abletoperformorganizationaland to the Navy be surface sonar and The extent of your contribution intermediate maintenance on depends, in large measure, upon yourwillingness allied equipments. AsSTG 3 or 2. your billetsin

7 Chapter I 111k SONAR TrCIINICIAN

and ability to accept increasing responsibilities inexperienced or poorly trained men may he as you advance. When you assume your PO assignedtoreplace them. In such a duties, you must accept a certain amount of circumstance, your skill and ex pe rien cc must he responsibility for military matters as wen as for used to help bring these men up to the standard occupational requirements of the ST rating. of those they replaced.

Military Leadership KEEPING UP WITH NEW DEVELOPMENTS Your military leadership responsibilities are about the same as those of petty officrs in You are responsible for keeping up withnew developmentswithinthe other ratingssince every a Navy.Practically pettyofficeris ve rythi militarypersonbefore becoming atechnical in theNavy is subject to specialist. Your responsibilities will extend both changepolici es, p ro cedures,cquipmen t, upward and downward. Senior petty officers publications, systems, and so on. As third class and junior enlisted personnel alike will expect and even more as second class, you must make you totranslate general orders into detailed, every effort to keep yourself informed of all practical,on-the-joblanguagethatcanbe changes and new developments that might affect your rating or your work. understood and executedby evenrelatively inexperienced personnel. In dealing with your Some changes will be called directly toyour juniors, itis up to you to see that they perform attention, but you must look for others. Try to their work properly. At the same time, you must develop a specialkind of ;lertness for new be ableto explain to your leading PO any information. Above all, keep an open mindon important needs or problems of these men. thesubjcetofnewsonars andassociated Although some broad aspects of military equ i pm e n t.Openmindedness is especialiy leadership are included in this text, the training important in the Sonar Technician rating because manual is not designed to give you extensive the Navy, in an effort to keep up with modern informationonmilitaryrequirementsfor modern advances in submarine development, is advancement to petty officer third or second. experimenting constantly with new detection, Material covering these requirements is found in fire control, and weapons systems. M i I itary Require/newsforPO 3 & 2 , NAVEDTRA10056(currentedition),and WORKING WITH OTHERS should be studied carefully. As you advance to third class and then to st,:ond class, you will be taking a greater part in Technical Leadership planning for the training of ASW personnelon your ship. At times, this training will affect a Your responsibilities for technical leadership large number of personnel not in your division are special to your rating and are directly related orevenyourdepartment.Itbecomes to the nature of your work. The dual role of increasingly important, therefore, to understand operatingandmaintainingtheship'ssonar the duties and responsibilities of personnel in systems is a job of vital importance. It requires other ratings. The more you know about related an exceptional kind of leadership ability that ratings, the more complete and comprehensive Lun be developed only by personnel who have a will be your training plansespecially those that high degree of technical competence and a deep require an interdivisional effort to achieve their sense of personal responsibility. Even if you are goals. fortunate enough tobe serving with highly skilled and well-trained sonar personnel, you will Communicating Effectively findthattrainingis-tillnecessary.Inthis respect. you will be expected to assist in the As your rcsponsibilities for planning with training of lower rated men for advancement. others increase, so also must your ability to Also, if some of the skilled men are transferred, communicate clearly and effectively. The bas':.:

3 8 IN TRODUC HON TO SONAR

requirementtor criCCtiVC C01111111111liattoll I hese prolh.ainS Mt.' designed to increase morale kn OW ledge ofyourown language. Usc ott;ilarge scale with increased retention as the appropriate language in speaking and in writing. logical by-product. Rememberthatthebasicpurposeof;ill The Navy has taken great strides in improving communication is understanding.To lead . its living standards. The food is better and even supervise, and train other men. you must be able the pay has become reasonable. These factors to speak and write in such a wa, that they can fulfill a man's basic survival and security needs, understand exactly what you mean. but we must use other motivating factors also to A secondrequirement foreffective promote retention. By learning to recognize communication in the Navy is a sound positivemotivation factors andtouse them knowledge of the "Navy way- of saying things. correctly, we will obtain better job performance Some Navy terms have been standardized for the andoursubordinateswill realiz.2 more purdose of ensuring efficient communication. satisfaction from their jobs. Wt.. are all capable of When a situationcallsforstandardNavy performing if motivated properly. terminology, use it. No one has all of the answers to effective management. However. the highest degree of Stillanotherrequirementforeffective e Ile c t iveness is realized whenleadership communicationisprecisioninthe:Iseof techniques are based upon the following list of technical terms. A command of the technical assumptions: language of the Sonar Technician rating will enable you to receive and convey irformation I.People a re not bynaturelazy, accurately and to exchange ideas with others. indifferent. uncooperative, or uncreative. Work Proper use of technical termsisparticularly is ;is natural as play or rest. important when you aredealing with lower 2.Tight controls and threats of punishment rated mencarelessly used technical terms will are not the only means of getting men to work. confuse an inexperienced man. A person who Men will exercise self-direction and self-control (loos not understand theprecise meaning of toward objectives to which they are committed. terms used in connection with the work of his 3.Every man must have a meaningful job. own rating is handicapped when he tries to read Withoutmeaningful work heisbored and official publications related to his work. He is useless. also at a disadvantage when he takes the written 4.Man isa growing, learning animal who examinations for advancement. craves recognition. 5.Most men learn to accept and to seek Increasing Retention responsibility. 6.The avciage man's intellectual potentials are only partially utilized. Most are capable of a Have you ever wondered why we have to go hir4h degreeof imagination,ingenuity,and into a port and starboard sonar watch, during creativity. operating periods, or why our sea duty tours are 7.Man by his nature is gregarious. One of so long? Let's face facts: Naval operations are his basic urges is his desire to be an integral part not going to change very much inthe near of some group. He must feelthatheisan future.Infact, due to budget cuts, we will important, contributing member of the group. probably be doing the same job with fewer men. Therefore, retention of the lower rated Sonar Do we, as leaders, really consider the needs Technician has become a critical factor and we and desires of our subordinates'? Most of us have must direct our attention toward this very real preconceived ideas of what a person's needs are. problem. We try to compare a subordinate's reactions to The Navy recognizes the problem and has various management techniques, and to what we institutedmany new"PeopleProgram:- think our own reactions would be under similar designedtohumanizethe Navyeffort, circumstances.Thus,wesetup a model highlightingtheindividual within the group. subordinate, usually based upon ourselves, and

4 9 (haith I I IIIti( )N \l I I (IINI(I 1N decidetomaikige,iccordinu IL)ourmoulers withinthc group shouldbe encouraged. :111 desiies, treating everyone the same. kiltthis is operator rais great pride in the tact that he \v;1.1 entirelythewrongiipproachsinceno tW0 IrsIiLdetect ;Idistanttarget.Likewise. individuals are alike, We each re,ki differently to competition \\ ith ot her groups can he stimulating. di! ferentsituations, Therefore. a good leader m)11.1r gang can1.1",!ll re the solution to ally must know and understandhis men and be 111.111cll\criv board problem quicker than any flexibleenough tozidjust Insmangement Quartermaster in thc techn iquesaccording toeach uI i \id Whenever po:sible. group &visions should Flexibility is a kev.0 StIcicsSrul le;RIcrship. be en CO ii rdgcil. Forexample.Jur* a Jobassignmentsshouldhe plannedto pre-exercise briefing. why not ask the group for challenge the ability of each Mdividual. Whcll opinions? -How do you think we should handle man masters one task. make his next one just a t Ids part of t he exercise. JoIles? Listen to your little more difficult. ke.7ping in mind that. for men and respect their opinions. -I hey may conic motivating purposes. succeeding is better than up with a good idea that you hadn't thought of. success. For e\arllple. turn-..ountingis a great L.\ery man will naturally work harder toward an challen12etoanew ST striker:liud. once he uhjcctic if lue takes part in making the decision becom -7,Ticient. Ids joh must be changed, If because he now has a personal interest in the not. lit ., become bored and Ins efficiencv will task. drop. If it's not possible to change his job right -Fhese are some of the ideas that can be away. then encourage competition among the employedtoimproveindividualand group watehstanders. Use any challenge you can think performance. Certainly. there are many others. oftokeephiminterested,andhishigh -Flue important thing is that we. as leaders. must performance should continue until Ilk job can considermoraleandretention.whichgo be changed. hand-in-hand.twoofourmostimportant responsibilities. We should occasionally examine Eachsubordinatemust be assigned our leadership techniques aid keep an open responsibility no matter how large or small the mindfor new and useful methods. -Flue new responsibility. We could Illake manyc,uanges in Navy management trend i towardasofter this area. For example. in most compartments. a a pproiuc h . re co gn izi ngindividual needs. card is posted on the bulkhead designating the However. the strong,stern approachisstill manresponsiblefor thatcomparment. avHlable for use when necessary. The next few Normally. the designated man is a son,or petty ye;,rs are going to be very challenging to all of us officer.Let'schange that.Assign the in the naval service. C'hallenge is our lifeblood, responsibility fortheappearanceofthe the driving force that keeps us going. Admiral compartmenttothecompartmentcleaner Hake- once said--"Ther: are no great men. himself. When he realizes that he, and not his Great men are just normal men who are forced senior petty officer, will have to answer for the to the meet the greatest challenge.- compartment if it is not ship-shape. he will take more interest and will do a better job. He will also work harder for another reason: he knows STUDYING FOR THE TEST that when he does a good job, he will receive the "well done- himself'. -Flue SonarTechnician,likehis Many of the factors used to motivate an contemporaries in other ratings. normally has in(Iividual can also be used to motivate a group. access to every publication used as reference Certainly, a good attack team must function as a materialforthe questions contained on Ins group. Some sonar controlsare manned by advancement-in-rating examination. groups and others are manned by "bunches of Trying to read aud study every manual or individuals.- To be effective, all of the efforts of publication on sonarisa waste of time and your teammustbegroupeffortsforthe effort. We each have a saturation point wieh accomplishment of goup goals. Competition most certainly would be exceeded if we tried to 10 IN I RoD1( 1ION 0) SoNAR

st OTF,111illr. I h )1VC1 CI. a pamphlet N VP11:8 NAVI'D I KA inunhci, !Hied.tle prod need which indlcatesexactly which the most lecent edittons and 111,l \ II reference material is used in writing the exam. ,uch N:\\A mill A editIon. This p,itilphlet, fOr Advancement

Stmly, N AV I'DTRA I 0052 (current edition), k C01111111' ( ) NoIll.e!,1(1(.11 I CarAT availableatyour Information ;Ind Education identificationNumbers. Office. NAVPERS/NAVED IRA number(s) of the coursescoveringsubjectmatterof any Theliibli(wraphyis an important reference prescribedtext(s) describediiicolumns 2 when preparing for :tdvanl....enient.Itis based on and 3 are listed. InLI few cases. compietion the Manual of Nary baistra manpower of the collrtie is mandatory. Perswinel(kcsilicatimisandOccupational Standards, NAVPERS I 8068 (current edi(ion), Column (5) APPlicabl'-' Rat' L'vds. Fs"'nt nidliststhetrainingmanualsandother for training manuals that are mandatory. the publications prescribed for use by all personnel lowest rate level for whicha publication is concerned with advancement-in-rate training and applicableislistedinthis column. Ifa with advancement examination writing. Thus. publication is mandatory'. then AI a the rate theBibliogra[hyprovidesaworkinglistof levels for which it is mandatory are shown. materialforenlistedpersonnelto studyin Note that, as pointed out in the Manual of preparation for advancement examinations, and VaIT EnlistedManpower and Personml it's the same list used by the item writers at the Classdications and Occupational ,Ytandards, NavalEduca tionandTraining Program NAVPERS 18068. all higher pay gradesmay Development Center. beheld responsibleforthematerial containedinpublications listed('or lower The first few pages of the pamphlet show rates in theirpathsofadvancement. themilitaryrequirementsreferenceswhich Asteriskswhichappearthroughoutthe applytoallratings. Thispartofthe listings indicate the Rate Training Manuals Bibliographyisof special importance atthe orNonresidentCareerCourseswhose E4/E5 levels itecause separate examinationson mandatory completion is specified by the military subjects are given locally at those rate Advancement Manual. levels. The remainder of the booklet contains reference listingsby ratings,using tlyc The rate training manuals are basedon the five-columr, format shown in figure I-I. professional and military quals from the Manual of Navy Enlisted Manpower and Personnel Column ( 1) Ratings.Thenamesand Classifications and Occupational Standards. With abbreviations of both service and general a fewexceptions,sufficientinformationis ratings are contained. All of the references presented in these manuals to coverevery qual. for Sonar Technician are grouped together Obviouslyaquallike"encode and decode on one list covering one or more pages. tactical signals" cannot be realistically covered. NorcanaSecretqualbecoveredina Column (2) Publication Titles. Titles and Confidential or unclassified manual. For these applicable parts of Rate Training Manuals typesof quals youhavetogotoother and other publications are shown inthis publicationsfortheinformation.The column. Notice that, when only certain parts Bibliography tells you where to look. of a book apply as references for a particular This rate training manual plus either the rate.just thoseparts(paratuaphsof STG or STS manual and Military Requirements chapters) arc listed. (See fig. I-I.) for PO 3 & 2 cover the majority of E4and ES ST quals. Bibliography (NAVEDTRA 10052. Column (3) Text Identification Numbers. current edition) references cover those quals This column identifies the references more thatcannot be adequately covered by thesetwo specifically.Thepublicationand manuals.

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7 1 2 INTRODUCTION TO SONAR

N AVEDT RA PUBLIC AT ION S Manual and because it contains dataon new equipment, policies, and procedures. Some of the NAVEDTRA publications that you will need to study or refer to as you prepare MANUFACTURER'S for advancement have been discussed earlier in TECHNICAL MANUAL this chapter. Some additional publications that you will find useful are listed here. When new sonar equipment is purchased by theNavy, the company manufacturing that Tools and Their Uses, NAVEDTRA 10085 equipment is normally tasked with providing a (current edition) manufacturer'stechnicalmanual (instruction book). These instruction books are then assigned BasicElectricity,NAVEDTRA10086 NAVSEA numbers by the Navy. For example: (current edition) Sonar communication set AN/BQC-I B, ICwas approved by the Navy in September 1964. The BasicElectronics,Vols. 1 and 2, DYN A-EMPIRE,INC.submitted a NAVEDTRA 10087 (current edition) manufacturer'stechnical manual anditwas assigned the NAVSHIPS number 95728. A large Servicing Techniques for Trans' torized and change was made to the manual in March 1968, PrintedCircuits, NAVEM RA 38001 andthemanual was reassigned NAVSHIPS (current edition) number 0967-932-2011. These manuals provide all of the technical information for a given piece NAVSEA (FORMERLY NAVSHIPS ) of sonar equipment and are indispensableto the PUBLICATIONS Sonar Technicain maintaining that equipment. Several publications issued by the Naval Sea EIBs AND EIMBs Systems Command will be of interest toyou. Although you do not need to know everything The Electronics Information Bulletin (EIB) that is given in the publications mentioned here, is a b i we eklyau thoritativepublication you should have a general idea of where to find con tainingadvanceinformationonfield information in NAVSEA publications. changes,installationtechniques, maintenance notes,beneficialsuggestions,andtechnical NAVSEA Technical Manual manual distribution. Articles of lasting interest arelatertranscribedintotheElectronics The Naval ShipsTechnical Manual (now Installation and Maintenance Book (E IM B), NA VSEA TechnicalManual),NAVSHIPS except forfield changes and corrections to 0901-000-0000, is the basic doctrine publication publications, which subsequently are reproduced of former Naval Ship Systems Command. The and stocked at NPFC, Philadelphia. These two manual is kept up to date by means of quarterly publications are essential beczuse of the advance changes. All copies of the manual should have all informationandthereferenceinformation ciianges made in them as soon as possible after available to the sonar maintenance technician. the changes are received. PUBLICATIONS PROMULGATED Naval Sea Systems Co mmand Jo urnal BY CNO (formerly, Technical News) The followingpublicationsseriesare The NSSC Journal,a monthly technical sponsored by CNO. publi ca t i on,containscurrentunclassified information on all aspects of shipboard problems. COMTAC Series The magazine is particularly useful because it presentsinformationthatsupplements and The term COMTAC is a label assigned to clarifiesarticlesinthe NAVSEA Technical that group of nonregistered communication and

8 1 3 Chapter 1THE SONAR TECHNICIAN tactical publications which CNO has designated U.S. NAVY TACTICAL to bepart of every command's allowance of DOCTRINE PUBLICATIONS requiredpublications.Thefollowing publications are included in the COMTAC series. Thetitlesofallpublicationsandthe descriptive paragraphs appearing here and under Naval Warfare Publications (NWPs) subsequentheadingsin thissectionare uncla ssi fied. Theclassification Naval Warfare Information ,tions ofeach publicationisindicatedatthe end (NWIPs) of the descriptiveparagraph.Thosepublications Fleet Exercise Publications (EXPs) marked with an asterisk are of particular interest to the STS. Allied Tactical Publications (ATPs) Allied Exercise Publications (AXPs) NWP 0 TACTICAL DOCTRINE PUBLICATIONS GUIDE includes the periodic USN Addenda to Allied Publications reviewprogram andprocedures, publication Miscellaneous Allied Publications procurement,a generalsummaryofeach publication, and guidance for the operation of a Registered Publications Series COMTAC publication library. (Unclassified)

A few of the publications sponsored by CNO NWIP 1-4 EXPERIMENTAL TACTICS aredistributedthroughtheRegistered contains experimental tactics and procedures Publications System (RPS), These publications and assigns their evaluation. If accepted by fleet must be accounted for, safeguarded, extracted, evaluation, the materialistransferredto the and destroyedin accordance with applicable appropriatepublicationinthe NWP series. instructions and directives published by RPS, (Confidential) supplemented where necessary by individual letters of promulgation. Tactical publications in NWIP11 -20MISSIONS AND the RPS are as follows: CHARACTERISTICS OF U.S. NAVY SHIPS AND AIRCRAFT contains information on U.S. ATP-6AlliedDoctrineofMine Navy and Coast Guard ships and aircraft, and Countermeasures illustrations of representative types. It includes ATP-24 Tactical Instructions for Conduct of themissions,characteristics,armament, and Mine Countermeasures enduranceofthevariousshipclasses, and performance data of aircraft currently in service. AMP-5 MineIdentificationand Disposal (Confidential) Manual AXP-5 NATO ExperimentalTactics and NWP 1 6 BASIC OPERATIONAL Amplifying Tactical Instructions COMMUNICATIONS DOCTRINE establishes thebasicdoctrine,policies,andprinciples PUBLICATIONS PROMULGATED governingoperationalcommunications. BY COMNAVCOMM The following publications are within the *USN ADDENDUM TO ATP28 cognizanceofCommanderNaval (REPLACES NWP 24 SERIES) presents the Communications (COM NAVCOMM): basic concepts and principles of ASW operations and amplifies the ASW chapters in ATP 1, Vol. Allied Communication: Publications (ACPs) I. (Confidential) U.S.NavalCommunicationsInstructions *NWP 3 3 ELECTRONIC WARFARE (DNCs) provides doctrine and procedures for electronic Joint Publications (JANAPs) 1 1warfare and includes information on electronic

9 INTRODUCTION TO SONAR countermeasures, counter-countermeasures, and operating, and the more common administrative acoustic warfare. It also provides information on signals.(Custodian:UnitedStates) types of electronic equipment and guidance for (Confidential) employment of electronicwarfareinnaval operations. (Secret) USN ADDENDUM TO ATP I(VOL. II), U.S. NAVAL SIGNAL BOOK,provides NWP 37NATIONAL SEARCH AND additional basic material, supplementing and/or RESCUE MANUALisajointpublication modifying ATP 1, Vol. II, for intraservice use by coordinatedbytheU.S.CoastGuard.It the U.S. Navy when operating separately from provides the various military forces and civilian the other Allied navies. (Confidential) agencies with a standard procedure for search and rescue. (Joint service publication) (Sponsor: ATP 3 ANTISUBMARINE EVASIVE Coast Guard) (Unclassified) STEERINGcoversevasivesteeringby formations, convoys, an-I ships to avoid attack USN ADDENDUM TO NWP37, by submarines. Itis intended for use by Allied SUBMARINE DISASTER SEARCH AND navies. (Custodian: United States) (Confidential) RESCUE OPERATIONS, outlines procedures particularly applicable to the search phase of SUPPLEMENT TO ATP 3, ZIGZAG PLANS peacetime submarine disaster search and rescue 10, 14, 15, and 17. (Confidential) Dperat ions. (Unclassified ) ATP 10 SEARCH AND RESCUE contains *FXP 1 SUBMARINE AND doctrine concerning search and rescue and is the ANTISUBMARINEEXERCISESestablishes Allied version of NWP 37. An appendix contains :actics and procedures for conducting submarine Annex 12 to the Convention of International ;xercises withcriteriaforevaluating results. CivilAviationandpresentsinternational :Confidential) standards and recommended practices for search andrescue.(Custodian:UnitedKingdom) FXP 3 SHIP EXERCISES provides exercises (Confidential) 'orall types of surface ships and guidance to xercise observers in evaluatin2 the exercises. *AXP I ALLIED SUBMARINE AND Confidential) ANTISUBMARINE EXERCISE MANUAL establishes tactics and procedures for evaluating J.S. COMMUNICATIONS theexercises.(Custodian:Canada) 'UBLICATION (Confidential) JANAP 119 JOINT VOICE CALL SIGN AXP 2 ALLIED TACTICAL EXERCISE 300K contains the voice call signs of all U.S. MANUAL containsstandardseamanship, ctivities. (Confidential) gunnery, torpedo, and miscellaneous exercises for use by Allied navies in training their forces forparticipation in AlliedOperations. 4ATO/ALLIED TACTICAL (Custodian: United States) (Confidential) )0CTRINE PUBLICATIONS ALLIED COMMUNICATION

ATP 1 (VOL.I)ALLIED MARITIME PUBLICATIONS 'ACTICAL PROCEDUREScontainsbasic ianeuvering instructions, tactics, and doctrine A C P 1 2 5 COMMUNICATIONS Dr all Allied navies. (Custodian: United States) INSTRUCTION RADIOTELEPHONE 7onfidential) PROCEDUREprescribesthebasic radiotelephone procedure that shall be used for ATP 1(VOL. II) ALLIED NAVAL SIGNAL radiotelephonecommunications.(Custodian: ,OOKcontainsstandardmaneuvering. United States) (Unclassified)

1 0 5 Chapter 1THE SONAR TECHNICIAN

ACP 1 65 OPERATIONAL BREVITY Two important restrictions are placed upon contains code words or phrases that are used for the item writer:First,his examination must standardizationandabbreviation.The code cover all of the quals, as indicated by the Manual words are designed for speed and conciseness of of Navy Enlisted Manpower and Personnel tra nsmissio n . (Custodian : UnitedSta tes) ClassificationsandOccupationalStandards, (Confidential) NAVPERS 18068 (currentedition),for the particularrate.Second,hisreferencesare restricted to those listed in the Bibliography for THE ADVANCEMENT EXAMINATION A d va n cemen tStudy,, NAVEDTRA10052 (current edition), or the secondary references All of the ST advancement examinations are contained in the references in the Bibliography. written by an item writer at the Naval Education Let's say for example, that somewhere in the andTraining ProgramDevelopment Center, STS 3 & 2 Rate Training Manual, which is listed Ellyson, Pensacola, Florida. The item writer is in the Bibliography, a reference is made to a responsible for constructing the 150-question ST publicationwhich isnotlisted in the examinations. The writer has a bank of many Bibliography; then that publication is also fair itemsthat havebeenusedonprevious game for test question material. examinations, and he will use many of the items Many of us are led to believe that we must at from his bankwhen hecomtructsan least pass each section of the test. Not so. No examination. He will also write new items. numerical grade is even assigned to each section. The examination questions are grouped by For profile sheet purposes, a letter is assigned to subject matter into categories, or sections. The.e each sectiontopoint out weak areas. This may be from 5 to 12 sections on a particuiar enables you to better prepare for the next exam. test.Eachitemiscarefullycheckedand Of course, if you miss most of the questions in rechecked to make sure it is a valid item. one section of the exam, it may pull your overall grade down below the passing score; but itis Unfortun;-:'!. tliere is an unavoidable delay your overall grade that determines whether You builtintoth, :unation system since the pass orfail, not your performance on each Bibliography is1....ited and distributed about individual section of the test. Thus, your test one in year advance.Forexample,the gradeis determined by the total number of Bibliography for the 1974 exams was printed in questions that you answer correctly and your the spring of 1973. As soon as the Bibliography relativestanding among your peersnothing is made available to him. the item writer at else. NETPDC begins writing the ST exams for the following yeai. During this pericd of time, many changes may bemadetothereference HOW TO QUALIFY publications listedin the Bibliography. These changes may invalidate some of the exam FOR ADVANCEMENT questions. What mustyoudotoqualifyfor Ho wever,thiswill notaffectyour advancement? The requirements may change examination grade. On the day that you take the from time to time, but usually you must satisfy advancement exam, the item writer at NETPDC the following: also takes that same test. For your benefit, he thoroughlychecksevery itemonthe 1.Have a certain amount of time in your examination to make sure none are outdated. present grade. Any outdated questions that he finds will not be considered when the test is graded. This has the 2.Complete the required military andra ting same affect as counting all four answers correct manuals. because any answer you pick for an outdated 3.Demonstrate your ability to perform all question is correct. Thus, you do not have to the PRACTICAL requirements for advancement worry about test items that contain superseded by completing the Record of Practical Factors, informat ion. NAVEDTRA 1414/1. 1 6 11 INTRODUCTION TO SONAR

E5 REQUIREMENTS 'El to E2E2 to E.1# E3 -E4 f E6 t E7 f E8 to E to E5 to E6 to E7 to E8 to E9 4 mos. 6 mos. 12 mos. 24 mos. service- 36 mos or as E-3. as E-4. as E-5. as E-6. b mos.2 years 3 years 6 years 9 years SERVICE comple- 36 mos. 36 mos. as L- 2.time in time in time in time in tion of as E-7. as E-8. service. service, service. Recruit service. 8 of 12 Training. 10 of 15 . years years Recruit Class A - time in time in Navy Training. for Pin . service service (C.O., DT3, . School may ad- PT3, . must be must be enlisted. enlisted. SCHOOL vance up . A ME 3, .:mix, to10% IINI3, . . : . .: . MNC.tt of gradu- . PN 3, . .. . ating , FTB 3, .... class.) .. MT 3 PRA CTIC A L Locally FACTORS premred Record of Practical Factors, NavEdTra 1414/1, must be chcck- completed for E-3 and all PO advancements. offs.

.. SpecifiA ratings must complete PERFORMANCE . . : applicable performance tests be- TEST ...... ,,,,,_:,, fore taking examinations. ENLISTED As used by CO Counts toward performance factor credit in ad- PERFORMANCE when approving vancement multiple. EVA LUAT1ON advancement. Navy-wide examinations Locally See EXA MINATIONS **prepared required for all PO Navy-wide selection board. tests. below . advancements. ... .: Required for E-3 and all PO advancements Nonresident career RATE TRAINING .::...... '. unless waived because of school comple- courses and MANUAL (INCLUD-'... . tion, but need not he repeated if identical recommended ING MILITARY ... course has already been completed. See reading. See REQUIREMENTS) ;.:. NavEdTra 10052 (current edition). NavEdTra 10052

. . (current edition). Commanding AUTHORIZATION Officer NAV EDTRA PRODEVCEN *All advancements require commanding officer's recommendation. t 3 years obligated service required for E-7, E-8, and E-9. # Military leadership exam required for E-4 and E-5. ** For E-2 to E-3, NAVEDTRAPRODEVCEN exams or locally prepared tests may be used. t t Waived for qualified LOD personnel.

Figure1-2.Active duty advancement requirements.

1 2 1 7 Chapter 1THE SONAR TECHNICIAN

El to E2 to E3 to E4 to E5 to Et; to REQUIREMENTS* E8' E9 E2 E3 E4 E5 EG ri 30 mos.30 mos.24 mos. TOTAL TIME W i th with with IN GRADE 4 nms.8 mos.0 mos.12 mos.24 inos.total total total 8 yrs 11 yrs 13 yrs serviceserviceservice TOTAL TRAINING DUTY IN GRADEI 14 days14 days14 days14 days28 days42 days42 thiys28 days

PERFORMANCE Specified intings must completeapplie:Wle TESTS Performance tests before takingexamination.

DRILL Satisfactoryparticipation as a memberof adrill unit PARTICIR\ 'HON in accordancewith BUPERSINST 5.101).42series.

PRACTICA L FACTORS (INCLUDING MILITARY RecordofPracticalFactors. Na vEd'Fra 1114/1.must REQUIREMENTS) be completedforall advancements.

RATE TRAINING MANUAL (INCLUDING Completionof applicable course or coursesmustbe entered MILITARY REQUIR E- in service record. MENTS) - Standard Exam required for all Pt) EXAMINATION Standard advancements. Standard Exain. Exam Also pass Selection Board. Military Leadership Exam for E-4 and E-5.

AUTIIORIZATION Cornmanding Officer NA V EDTHA PRODEvcEN

*Recommendation by commanding officer required for all advancemerns. 4Active duty periods may be substituted for training duty.

Figure 1-3.--Inactive duty advancement requirements.

1 8 INTRODUCTION TO SONAR

4.Be recommended by your commanding TheNavy'ssystemprovidescreditfor officer after the pettyofficers andofficers performance, knowledge, and seniority; and, supervising your work have indicated that they while it cannot guarantee that any oneperson consider you capable of performing the duties of will be advanced, it does guarantee that allmen the next higher rate. within a particularratingwillhaveequal 5.Demonstrate your KNOWLEDGE by advancement opportunity. passingwrittenexaminationsonthe occupationalandmilitaryqualification A change in promotion policy, starting with standards for advancement. the August 1974 examinations, changed the passed-but-not-advanced (PNA) factor to the high Some of these general requirements may be quality bonus point (HQP) factor. Under this modified incertain ways. Figure 1-2 gives a policy, a man that passed the examination, but more detailed view of the requirements for was not advanced, can gainpoints toward advancement of active duty personnel; figure 1-3 promotion inhis next attempt. Up to three givesthisinformation forinactiveduty multiplepointscan be gainedinasingle personnel. Remember that the qualifications for promotionperiod.The points can then be advancementcanchange.Check with your accumulated over six promotion periodsup to a division officer or training officer to besure that maximum of15. The addition of the HQP you know the most recent qualifications. factor, with its15-point maximum, raises the Advancement is not automa tic. Even though number of points possible on an examination you have met allthe requirements, including multiple from185 to200. This gives the passing the v :n examinations, you may not examinee added incentive to keep trying for be able to "s:. . on the crow" or "add a stripe." promotion in spite of repeated failure to gaina The number of men in each rate and rating is stripe because ot' quota limitations. controlled on a Navywide basis. Therefore, the number of men who may be advanced is limited All of the above information (except the by the number of vacancies that exist. When the examinationscore andthe HOP factor)is number of men passing the examination exceeds submitted with your examinationanswer sheet. the number of vacancies, another system must After grading, the examinationscores for those be usedtodeterminewhich men may be passing and the HQP pointsare added to the advanced and which may not. The system used other factors to arrive at the final multiple.A is the "final multiple" and is a combination of precedence list which is based on final multiples, three types of advancement systems. is then prepared for each pay grade withineach rating. Advancement authorizationsarethen Merit rating system issued, beginning at the top of the list, for the Personnel testing system number of men neededtofillthe existing Longevity, or seniority, system vacancies.

METRIC SYSTEM

The Metric System Single-Subject Training Manual and its associated OCC-ECC form a self-study package (NAVEDTRA 475-01-00-75) to train Navy personnel in conversion from the U.S. Customary System to the International System. Order the SSTM by stock number 0507-LP-475-0000 from NPFC, Philadelphia, and the OCC-ECC by NAVEDTRA 475-01-00-75 from the NAVEDTRAPRODEVCEN, Ellyson, Pensacola, Florida.

1 9

14 CHAPTER 2

HISTORY AND DEVELOPMENT OF ASW

DuringWorldWarII,submarinessent tzeneral nature. In your studies, though, you will millions of tons of shipping to the bottom. Early learnmanydetailsaboutsubmarine inthewar,England'slifelineswerenearly characteristicsandtactics.Suchknowledge strangledby German.-,ubmarines.American makes it easier for you to detect submarines and submarines played a large role in the defeat of hold contact after detection. Mr-,t of this text Japan by sinking nearly all her merchant marine. concerns our own submarines, but foreign navies Obviously, the submarine is a potent weapon, usually have submarines of comparable ability. requiring equally effective countermeasures. The United States and Great Britain wereuccessful HISTORY AND DEVELOPMENT in developing equipment, weapons, and tactics that enabled the destruction of the German The first successful submarine was built in submarine force. Japan, however, never was able 1620byCorneliusVanDrebel, a Dutch todevelop aneffectivedefense against our physician. During repeated trials in the Thames submarines. River, he maneuvered his craft successfully at Since World War II the submerged endurance depths of 12 to 15 feet beneath the surface. of the submarine has become sufficient to cause Various other European designers of that difficulty in locating it. The problem increases as time constructed submersiblecraftalso, but the submarine goes constantly faster, deeper, they failed to arouse the interest of any navy in andstays down longer. To cope withthe an age when the potentialities of submarine modernsubmarine, we nowhavebetter warfare were inconceivable. detection devices, more modern weapons, and Most of the early craft were wooden frames, newer ships; but the battle for supremacy is a covered with greased leather or similar material, never-ending one. and propelled by oars. Different methods of submerging were thought of and some were even tried.One inventor'sdesignconsistedof a THE SUBMARINE number of goatskin bags built into the hull, each connected to an aperture in the bottom. He All Sonar Technicians are concerned with planned to submerge the craft by filling the thehuntforanddestructionofenemy skins with water and to surface it by forcing the submarines. It is especially important, therefore, water out of the skins with a "twisting rod." thatyou knowthecapabilitiesof enemy Although his vessel was never built, it seems that submarines, and know them well. Innumerable this design was the first approach to the modern questions will come to you over a period of time ballasttan k.Anotherinventoractually or after a course of events in antisubmarine submerged his craft by reducing its volume as a warfare (ASW) operations: How fastcana result ot' contracting the sides through the use of submarine dive orturn?Howdoesthe hand vises. submarine use depth? What is the submarine's Ideas were plentiful. Some of them were top speed when submerged? Because this text is fancifuland grotesque, but some contained unclassified, many of theanswers areof a elements capable of practical application. Lack

15 2 0 INTRODUCTION TO SONAR

offullunderstandingofthephysicaland blockadingCharlestonHarbor. The hitwas mechanical principles involved, coupled with the accomplished by a torpedo suspended ahead of almostuniversalconvictionthatunderwater the Confederate 11UNLEY as she rammed the navigation was impossible and of no practical Union frigate HOUSATONIC, and is thefirst value, kept postponing the attempt to utilize a recordedinstance of asubmarine sinking a submarineinnaval warfare during the early warsh ip. period. Thesubmarinefirst became a major A submarine was first used as an offensive component in naval warfare during World War I, weaponduringtheAmerican Revolutionary whenGermanydemonstrateditsfull War.The TURTLE, aone-mar submersible potentialities.Wholesale sinkingofAllied designed by an American inventor named David shipping by the German U-boats ahnost swung Bushnellandhandoperatedbyascrew the war in favor of the Central Powers. Then, as propeller, attempted to sink a British man-o-war now.the submarine's greatest advantage was in New York Harbor. The plan was to attach a that it could operate beneath the ocean surface charv,e of gunpowder to the ship's bottom with wheredetection wasdifficult.Sinking a screws and to explode it with a time fuze. After submarine was comparatively easy, once it was repeated failures to force the screws through the found: but finding it before it could attack was copper sheathing of the hull of HMS EAGLE, another matter. the submarine gave up and withdrew, exploding its powder a short distance from the EAGLE. During the closing months of World War I, Although the attack was unsuccessful, it caused theAlliedSubmarineDevicesInvestigation the British to move their blockading ships from Committee was formed to obtain from science the harbor to the outer bay. andtechnologymoreeffectiveunderwater detection equipment. The committee developed On 17 February 1864. a Confederate craft, a areasonablyaccuratedevicefor locatinga hand-propelled submersible, carrying a crew of submergedsubmarine.Thisdevicewasa eight men. sank aFederal corvette that was trainable hvdrophone_ which was attached to

. SO.

71.1-346 Figure 2-1.Guppy submarine.

16 Chapter 2HISTORY AND DEVELOPMENT OF ASW

the bottom of the ASW ship and used to detect Theworld'spioneernuclear-powered screw noises and other sounds that came from a submarine is the USS NAUTILUS (SSN 571). submarine. Although the committee disbanded (See fig. 2-2.) The NA UTILUS, commissioned in a ft er War I, World theBritishmade September 1954, is 320 feet in length, witha improvements on the locating device, during the standard surface displacement (SSD) of 3180 interval between then and World War II, and tons, ard is designed for traveling faster under named it ASDIC after the committee. the water than on the surface. American scientists further improved on the device, calling it sonar, a name derived from the One of our fastest submarines is the USS underlined initials of the words sound navigation SKIPJACK (SSN 585), figure 2-3, whose hull is and ranging. a radical departure from the conventional idea At the end of World War II, the United of submarine hulls. Her diving planesare on the Statesimprovedthe snorkel(adevicefor sail, resulting in increased maneuverability. bringingairtothe crew and engines when operating submerged on (liesels) and developed An intensive building program for nuclear theGuppy(shortfor submarines has been in effect for severalyears, greaterunderwater and many new ships have joined the fleet. The propulsionpower),a conversionofthe fleet-type submarine of World War II fame. A USS GEORGE WASHINGTON (SSBN 598)was Guppy submarine is shown in figure 2-1. The thefirst submarine designed to launch, while superstructure was changed by reducing the submerged, the POLARIS missile. surfacearea,streamliningeveryprotruding object, and enclosing the periscope shears ina GENERAL DESCRIPTION streamlined metal fairing. Performance increased greatly with improved electronic equipment, A submarine ranges in length from about 50 additional battery capacity, and the addition of feettomorethan400feet.Diving is the snorkel. accomplished by controlled flooding of ballast

2 2

71.1-571 Figure 2-2.USS NAUTILUS (SSN 571).

17 INTRODUCTION TO SONAR

71.1-585 Figure 2-3.USS SKIPJACK (SSN 585).

tanks. To surface the submarine. compressed air 1-1/2 feet per second and can turn 900 in a little expels the water from the tanks. over I minute, using full rudder and 5 knots of Probablythesmallest submarinesinthe speed. world belomt to the ex-German SEAHOUND class (now in Russian possession). They are 49 Propulsion feet long and displace only 15 tons. Somewhat heavier, but stillin the midget submarine class, Diesel electric submarines use diesel engines are the U.S. Navy's X-I and the British SHRIMP forpropulsion. when surfaced. and ftitteries class. The X-1isless than 50 feet long and when submerged. Nuclear-powered submarines displaces 25 tons. Boats of the SHRIMP class are get their propulsion from atomic reactors. slightly longer and displace 30 to 35 tons. NUCLEAR SUBMARINES.Atomic power At the other extreme are the bulk of the has brought close to reality the dream of having U.S.Navy's submarines,includingthefatest atrue submarine; thatis.one of unlimited nuclear-poweredsubmarines.Some of these submerged ships are over 400 feet long and displace more enduranceand range.The ;V:1UTILUS refueled for the first time over I than 7000 tons (SSD). Others, designed for yearaftershecommencedoperating.The speed and maneuverability, ar ,! not quite as long and displace less tonnage. TRITON circumnavigated the world completely submerged.The.VA UTILUS an d SK:17'E Some submarines can cruise in ,!xcess of 20 pioneered exploration of the north polar seas knots submerged. A type of dies,,1 submarine beneath the 1(ecap,all made possible only by used by the Germans in World War IL which is a ii u c lerenerfty.The human factor andthe part of the Russian fleet. can dive at a rate of quantity of' supplies that can be carried are the

18 9,3 Chapter 2HISTORY AND DEVELOPMENTOF ASW main limitations to the endurance ofmodern submarines. ATTACK SUBMARINES (SSN) FLEET BALLISTIC The FBM is primarily designedas a threat to MISSILE SUBMARINES (SSBN) anation'slandareas. On the other hand, consider the dangers which the modernattack The basic purpose for the creationof a submarines (SSN) fhwre 2-5,pose on a nation's weapons system such as the FBM (fig. 2-4) isto surface fleet. History has amply demonstrated act as a nuclear deterrent toa general war. The thestrategic FBM isperhaps the importanceoftheattack most sophisticated and submarin. The combination ofnew hull design costlyweapons systemin existence andis and nuclear power have made the SSNgreatly capable of wreaking havocon a potential enemy. superior to its predecessor. This superiorityis so These ships are capable of high speeds,great great that most nations have been forced depths, andprolonged to submergence. As developnewerandmoreeffectiveASW formidable as these ships appearto be, effective programs to maintain the balance of countermeasures have been developed which power. Moreover, the primary mission of theattack make the FBM vulnerableto detection and submarine is ASW. destruction. For an FBM to remaina deterrent, it must cloak itself in nearly absolutesilence. It must patrol a given area without being detected SUBMARINE ARMAMENT and must maintain the capability of detecting Armament of a submarine dependson its enemy ships over great distances. design andniission. USN attack submarines

71.1-629 Figure 2-4.Ballistic missile submarine (SSBN).

2 4 19 INTRODUCTION TO SONAR normally carry only torpedoes and SUBROC, loadedwithupto1000 pounds of IIBX but they may be employed as minelayers. Fleet explosive. ballistic missile submarines, depending, on type, Underwaterexplosionofthetorpedo carry 16 POLARIS or 16 POSEIDON missiles, in warhead increases its destructive effect. When a addition to torpedoes. In the case of the new projectileexplodes,apartofitsforceis and larger TRIDENT submarines, the missile a bsorbed bythesurroundingair. Upon complement is 24 TRIDENT missiles. FBMs are explosion of the torpedo warhead, the water alsoequippedwithtorpedotubesfor transfers ilmost the full force of the explosion self-defense. to the hull of the target ship. Guppy submarines (now inpossession of TORPEDOES forei,2n allies) are fitted with 10 tubes, 6 in the bow and 4 in the stern. Spare torpedoes are The torpedo is a self-propelled underwater carried in ready racks rlear the tubes. On war weapon having eitherahigh-explosive or a patrol, a submarine of th:s type usually puts to nuclear warhead. Conventional warheads are sea with a load of 28 torp2does aboard.

7410

.0"

71.128 Figure 2-5.Attack submarine (SSN).

20 Chapter 2-- HISTORY AND DEVELOPMENT OF ASW

Torpedoes are propelled by gas turbines or ,the latest tactical information, thereby providing electric motors. Turbine types have maximum the weapon with maximum adaptability. The speeds of 30 to 45 knots. with an effective range torpedo guidance and control circuitry receive of as much as 7-1/2 miles. Electric torpedoes initial run plan instructions (preset) from the usually have less speed and range than turbine fire control system. And, after each launch, fire types: but, from the submariner's point of view, controlmayupdateinitialinstructions by they have the advantage of leaving no visible onnmand guidance. wa ke. Torpedoesareofthestraight-running. MINES acoustic-homing,orwire-gandedtypes.The straight-running torpedo has automatic control Navy minesarethin-casedunderwater devices tlmt hold it on a preset course at a preset weapons with a heavy load of high explosives. depth, whereas the acoustic-homing type can They may be laid by both aircraft and surface steer itself towardits target.It may be either craft.butsubmarinesareemployedfor active or passive. Theacti ve acoustic torpedo minelaying when secrecy is required or when the sends out pulses of sound and homes on the area to be mined is beyond the range of aircraft. echoes that return from the target. Passive types Mines may be of the bottom or moored typo. home on the noises emanated by thc target. The Bottom mines rest on the ocean floor and are wire-guided type of torpedo is directed to the highly effective in shallow water. Moored mines target by signals sent through the wire from the are positively buoyant. A cable, attached to an launching submarine. anchor on the sea bottom, holds the mine ata predetermined depth beneath the surface. Mines may be actuated by contact with a vessel, by a Mk 37 Torpedo vessel's magnetic field, by noise, or by pressure differences created when a vessel passes over the The Mk 37torpedo is anelectrically mine.Acoustic-,pressure-,and controlledandpropelledtwo-speedtorpedo magnetic-influenced mines may be set to permit with an active-passive acoustic homing system. the passage of several ships, then explode under This torpedo,launchedfrom submarinesis the next one to pass over. effectiveagainsteither surface or submarine targets. Some mods are wire-guided. making FLEET BALLISTIC theminvulnerabletoseveralenemy MISSILE SYSTEM countermeasures. The fleetballisticmissileisatwo-stage Mk 48 Torpedo underwater-to-surface inertiaily-guidedballistic missile.Ithas undergone several evolutionary TheMk 48torpedo is a high-speed. stages since 1960. The first unit, the POLARIS deep-running.long-range,submarine-launched A-I, has a range of 1200 nautical miles. The A-2 weapon usedagainst submarines and surface model, first test-fired in 1961, reacheda target ships. Both acoustic and nonacoustic operating at 1500 NM. Next came the A-3 (2500 NM), modes are available. Acou.,tic modes are active. firstsuccessfully fired by the USS ANDREW passive, or combination. The torpedo may be JACKSON (SSBN 619) in 1963. Currently the operated in the acoustic mode when used against POSEIDON (C-3) is being used in the FBM fleet surfaceor 'mergedtargets.Nonacoustic inadditionto the POLARIS A-3. The next operation may be used against surface targets generation is the TRIDENT missile of which 24 only. are carried on board the new TRIDENT class su bum rine. Command guidance (wire link) may be used The first version is planned to have a range for both acoustic and nonacoustic shots. This of 4000 NM. With such a range, the launching allows the launch vessel's on-board computer to submarine could hide in any ocean and senda apdate torpedo guidance and control logic with inksile to any major city in the world.

21 2 6 INTRODUCTION TO SONAR

NAVIGATION CENTER CONTROL ROOM OFFICER& WARDROOM ATTACK CENTER CPO QUARTERS MISSILE CREW'S QUARTERS COMPARTMENT OFFICERS MISSILE QUARTERS CONTROL TORPEDO ROOM ENGINE ROOM TUNNEL CENTER

111111111 gra:-

-111 ligrinettrj3111 ,ft

BATTERY RE ATOR GYRO ROOM CREW'S MESS COMPARTMENT AUXILIARY CREWS CREW'S MACH NERY WASHROOM QUARTERS SPACE

71.1 Figure 2-6.SSBN class submarine; interior arrangement.

The FBM(fig.2-6)isdesignedtobe After launch,ignition of thefirststage launchedfrom a submarinecniising(or rockettakesplaceshortlyafterthemissile stationary) below the ocean's surface. The two breaks the surface of the sea (fig. 2-7). This is powerfulsolid-propellantrocketmotorsare the beginning of powered flight and the inertial capable of lifting the warhead high above the guidance portion of the trajectory. The first range of any known antimissile missile, at a stage propels the missile far into the atmosphere. speed exceeding ten times that of sound, and of The first stage then separates and the second placing it into a free fall trajectory which will stagerocket motor continuesto propel the carry it to its target with deadly accuracy. Each missile to a point above the earth's atmosphere. warhead of the POLARIS or POSEIDON is a When the missile has reached the proper velocity compact andpowerfulnucleardevice.The and -,oint on the trajectory, the reentry body explosive power inone shipload of sixteen .en.ites and the warhead follows aballistic missiles exceeds the total amount of explosive tr. ,..ory to the target. MIRV warheads can be power expended byallof the participating ,-atelytargeted. The time of reentry body countries in World War II, INCLUDING the ..,.ationdeterminestherangewhichthe atomic bombs dropped on Japan. ,vurrid will span. The range can ba

11 2 7 Chapter 2HISTORY AND DEVELOPMENT OFASW

varied inthis way from about 575 to about Each warhead dives on its target ata steep 2500 nautical miles. angle and at several times the speed of sound. The materialsfortheouter surfaceof the Since there are no external control surfaces warhead have been specially developed to resist on POLARIS or POSEIDON, changes in the the high temperatures generated by friction with trajectory are accomplished by deflecting the jet the atmosphere at reentry speeds, and suitable stream from its motors. A pre-comput ideal insulation is provided between the outer skin trajectory is preset into the missile. Thepreset and the internal components to prevent damage information takes into account the movements to the warhead. of the target, of the launching point, and ofthe The SSBN providesamobile launching missile with respect to inertial space during the platform which is extremely difficult to detect. time offlight. The warhead release velocity It can remain submerged forvery long periods of which the missile must attain along its trajectory time and cruise to almost any position within on the basis of a fixed time-of-flight is also the oceans of the world. By use of its inertial preset.Thelaunching submarineaccurately navigation system, it can provide the precise lire determines its launching position byuse of an control data required to place each warheadon inertiai navigation system, and the positionof target. the target on the earth surface isa known factor. While in the power stage of flight, the missile SUBROC MISSILE SYSTEM continuously measures its linear accelerationson the basis of itsinertial system and alters its S )(' is an underwater-to-air- trajectory to offset the outside forces causing to-unck:.watcv lissile designed to destroyenemy unwanted accelerations. When the missile ison a submar.;itlong range. The missile consists proper trajectory and a correct velocity has been essentiall ()a nuclear depth bomb and a rocket attained, the warheads are released and proceed motor joined together. The launching submarine toward the target with no further correction cai-ries the equipment for detecting andtracking possible. t he enemysubmarine,the firecontrol

BALLISTIC FLIGHT

TERMINATION POWERED FLIGHT 2ND STAGE IGNITION 1ST STAGE SEPARATION ( INERTIAL GUIDANCE 1 ONLY ) ST STAGE IGNITION

33.269 Figure 2-7.POLAR I S trajectory (not to scale).

23 2 8 INTRODUCTION TO SONAR equipment for computing the target information the missile is switched from the thrust vectoring and providing the necessary pre-launch missile mechanismtoaerolins.During theballistic information, and the equipment for launching portion of the flight, the aerofins control the themissile. The missile is designedtobe missileinroll and azimuth. Pitch guidance is launched (fig.2-8) from a standard submarine initiated at or near the zenith of the trajectory torpedotube, usingconventionalejection to directthe missile to the desired point of methods.Uponbeinglaunched,therocket impactonthewatersurface.Guidanceis motor is ignited at a safe distance from the firing terminated at a predetermined height above the ship. The missile'sflightthroughthe airis water, and the last portion of its above-water controlled by an inertial guidance system which trajectory is free fall. At water impact, a timer functions in accordance with the fire control mechanism starts and causes the warhead to infcrmation set-in prior to launch. In addition to detonate at the proper time. providing the propulsive force for the missile, Moredetailedinformation on SUBROC, the rocket motor furnishes power for controlling POSEIDON, and POLARIS can be found in the thethrustvectoring mechanism, duringthe appropriate classified publications. boost phase, and the thrust reversal necessary to accomplish rocket motor separationAt the ANTISUBMARINE UNITS proper point in its trajectory, the rocket motor separates and the missile continues in a free-fall The appearance of new equipment and flight. At the time of separation, the control of weapons and the modification of their older

2 9 42.227 Figrue 2-8,Artist's view o ic trajectory of SUBROC.

24 Chapter 2-HISTORY AND DEVELOPMENTOF ASW

counterparts have resulted in the demand for Armament consists of 5-inch and 3-inch more modern versions of ASW units. These may guns, and a variety of antisubmarineweapons, be brand new units or highly modifiedships or such as torpedoes and ASROC (antisubmarine submarines of our ASW forces. Someexamples rocket). of ASW units follow. Displacement varies from about 3000tons to over 7000 tons. The newest type of destroyer AIRCRAFT CARRIER (CV) in the fleet (fig. 2-10), the DD 963(Spruance) One of the class, has a displacement of approximately780- missions of the (CV) isto tons, a length of 560 feet, anda beam of over 50 support and operate aircraft for antisubmarine feet.Armamentconsistsoftwo warfare operations in additiontoits normal 5-inch/54-caliberguns, mission as an actual carrier. ASROC,torpedoes, surface-to-surfacemissiles, andtwo ASW helicopters. This destroyer is driven byan all-gas DESTROYER (DD) turbine propulsion system andtwo controllable pitch propellers. Alldestroyer-typeshipsare namedfor deceased members of the Navy, MarineCorps, GUIDED-MISSILE DESTROYER (DDG) and Coast Guard, and Secretaries ofthe Navy. Destroyers(fig.2-9) are multipurpose ships The DDGs of the Charles F. Adams useful in ahnost any kind of naval class operation. have a displacement of about 4500tons. Their They are fast ships witha variety' of armament armament but consistsof two5-inch/54-caliber little or no armor. For portection,they single-gun mounts (one fore and depend on their speed and mobility. one aft) and a twin TARTAR missile launcher aft (somehave a The principal function of destroyersis to singlelauncheraft). operate Allhavean ASROC offensivelyanddefensivelyagainst launcher amidships (fig.2-11). Several of the submarines and surface ships, andto defend against air attack. They also provide postwar FORREST SHERMAN class (fig.2-12) gunfire have been converted t^ DDGs byreplacing the support for amphibious assaults and perform number 2 ,2,un mount witha TARTAR missile patrol, search, and rescue missions. launcher.

3 0

71.129 Figure 2-9.USS WILLIAM M. WOOD (DD715).

25 INTRODUCTION TO SONAR

'--7771-7 -413R I 74-t- a - "91

71.130 Figure 2-10.DD 963 (SPRUANCE) class.

FRIGATE (FF) tons in World War H to over 4000 tons in the KNOX (FF 1052) class. Their armament varies Frigates(fig. 2-13) resemble destroyers in from class to class; that of the KNOX consists of appearance; but they are slower, having only a a single 5-inch/54-caliber gun, ASROC, LAMPS, single propeller, and carry less armament. The and antisubmarine torpedoes. mission of FFs is to screen support forces and convoys andtooperateoffensivelyagainst GUIDED-MISSILE FRIGATE (FFG) submarines. They also may be used for shore Guided-missile frigates are basically the same bombardment. Frigates,formerlydestroyer as frigates with the addition of single TARTAR escorts, have grown in size from about 1500 missile launcher. (See fig. 2-14.)

33.272 Figure 2-11.ASROC launch from USS HENRY B. WILSON (DDG 7). Chapter 2-- III sTo RY AND DEVI:L.0PM kW 01: A SW

Figure 2-12.FORREST SHERMAN class destroyer (DD). 3.76

-:17, - - -:"- -% ^.-.... 7*" -

,

,

Figure 2-13.USS ALYWIN (FF 1081) firing ASROC. 134.87-1081

17 31 iNTRODIA TION TO SONA R

71.131 Figure 2-14.USS RAMSEY FFG-2 (BROOKE class).

SI

1 ....!...,

--:se,------.. . IF-I .: . 7,. . , -,.. 0, ,,...... ,...,-...... !. .4,

..

N.,,.. -4 .

Figure 2-15A.USS GRIDLEY (CG 21), 134.84 3 .3 Chapter 2 HISTORY AND DEVE LOPM ENI' OF ASW

GUIDED-MISSILE newer nuclear-powered guided-missilecal iser, CRUISER (CG ) (CGN ) USS SOUTH CAROLINA (CGN 37). She hasan overall length of 596 feet. a beam of 61feet, Guided-missile cruisers are al several classes, andaspeedinexcess of 30 knots. Sheis differing from each other mainly intype and equipped with the most advancedsonar and placement of their armament, althoughsome are antisubmarine weapons. smaller than others. The USS I3ELKNAP (CG 26), for instance, displaces 6700 tons. Shehas a twin launcherforwardthatcanfireboth ANTISUBMARINE ARMAMENT TERRIERmissilesandASROC, a single 5-inch/54-caliber gun aft, and two 3-inchguns Onefactorisresponsibleforeffective amidships. The USS LEAHY (CG 16) displaces countermeasures against submarines: that is. the 5600 tons. has a twin TERRIER launcherfore sound the submarine itself generates. As ASW andaft, four 3-inch guns, andan ASROC programs have been developed, a vastarray of launcher amidships. The nuclear-powered USS acoustic weapons have been produced. These BAINBRIDGE (CGN 25) is about 1000tons weaponsoperate by using sound detecting heavier than the BELKNAP, with essentiallythe methods and feature active sonar, passive same armament. A guided-missile sonar cruiseris and a combinationofboth. shown in figure 2-15A. Figure 2-1513 shows Such the countermeasures.ofcourse,become less

;mull - 14. *"/

444 . -

71.132 Figure 2-15B.Underway view of USS SOUTHCAROLINA (GN 37).

29 INTRODUCTION TO SONAR effective as submarines are designed to generate ballisticprojectile.Themissile hastwo less noise. configurationsone with a depth charge andone with a torpedo. ASROC Thegoalachievedby ASROCisthe The ASROC, whose launcher is shown in destruction of submarines at long ranges. This figure 2-16, is a subsonic, shipboard-launched, objective is achieved by delivery of a torpedoor solid-fuel, rocket-propelled antisubmarine nuclear depth charge through the air toa point in the water from which it can either attack under the most favorable circumstancesor have the submarine within its lethal radius (fig. 2-17). The payload is a part of an unguided missile whichispropelled by arocket motor and stabilized by an airframe throughout its powered flight.Separation timers jettison the airframe and motor after a preset time. From separation towaterentry,differentmethodsof stabilization are employed, depending on the payload. The depth charge descent is stabilized by afin network during the entire drop. The torpedo also has such a network; but it employs, inaddition,paLcnute staeilization.Besides stabilizing the torpedo descent, the parachute also decelerates it to a safe water entry velocity to avoid damaging the highly sensitive electronic LEFT REAR components.

Before the missile is launched, the submarine is located by sonar; and the range, bearing,and other pertinent data are transmitted to the fire controlsystem.Thefirecontrolsystem automatically computes the anticipated target position, sets the rocket motor thnist cutoff velocity and the time to airframe separation into an ignition and separation assembly, located within the airframe, on the desired water entry point. In this way, the missile can be fired at will by simply closing the firing circuit.

TORPEDOES

There are four principal ways to launcha torpedo: by letting it swim out of the tube, by firing it from a tube, by dropping it froma rack, or by propelling it part of the way to its target RIGHT FRONT as a rocket payload. Aircraftdrop torpedoes from launching racks. Usually, an aircraft carries two torpedoes; 15.106 a helicopter can carry one or two torpedoes for Figure 2-16.ASROC launcher. ASW work. 30 3 5 Chapter 2HISTORY AND DEVELOPMENTOF ASW

Figure 2-17.ASROC. 15.114

The Navy's older destroyers,aswell as CCt... TRU,. < JUNCTION BOX FRAM destroyers.DDGs, andCGs,carry torpedoes in the 3-barrel Mk 32 launcher (fig. 2-18). Twin mounts can fire from either side. They can betrainedthrough a wide arc so that torpedoes may be fired through a widerange of bearings. Compressed air expels the torpedoes from the tube with enough force to clear the ship.

Mk 44 Torpedo 1PAIN.NG RANDLE TRAINI%G GEAR ( ARM ASsi:MBLY ) BREECH MECHANISM The Mk 44 torpedo (being phased out) isan electrically controlled and electrically propelled 3.129 antisubmarine weapon withan active acoustic Figure 2-18.Mk 32 torpedo tube.

31 INTRODUCTION TO SONAR

134.95 Figure 2-19.P-3 ORION, land-based long-range patrol craft.

homing system. The torpedo can be launched 46, which givesitgTeater speed, range, and from surface ships or aircraft and isone of the depth capabilities. torpedo payloads for ASROC. The torpedo is designed to attack submerged submarines traveling at moderate speeds. After AIRCRAFT enabling, the torpedo searches for a target by active acoustic means while maneuvering ina The use of aircraft in conjunction with ships depth varying helical path. Echoes from the and submarines adds greater capability and target cause the torpedo to steer toward the versatility to ASW. Areas of surveillancecan be target until contact is made. If the torpedo loses enlarged; ranges can be extended for detection the target,it searches for a short time in the and attack; and diversified weaponscan be used. general direction in which it is traveling and, if Two types of aircraftare used in ASW: the unsuccessful in relocating the target,resumes a helicopter for close ranges and the fixed-wing helical search. aircraft for long ranges. The helicopteruses a The acoustic homing system of the torpedo dippinsonar; that is, one that may be lowered also has a passive feature that allows the torpedo from the aircraft for searching and retracted for to respond to an acoustic noise source whose flight. Both helicopters and fixed-wing aircraft frequr-Acy level is within the sensitivityrange of usemagneticanomalydetection(MAD) the receiver. During the torpedo's normal search equipment whereby they detect the submarine pattern, passive homing on a target noise source by variations in the Earth's magnetic lines of aids in target acquisition, increasing the attack force. capabilities of the weapon. Aircraft also use other devices for detecting the presence of submarines. One of these devices Mk 46 Torpedo isthc sonobuoy, whichis dropped into the water by the aircraft and then monitored by The Mk 46 torpedo is the successor to the radio. Sonobuoys arc described in chapter 6. Mk 44. The principal difference between the The aircraft also can be used asa tactical two is the improved propulsive power of the Mk vehicle to launch a weapon at the submarine.

323 7 Chapta 2IIISTORY AND DEVELOPMENT OFASW

71.133 Figure 2-20.S-3A VIKING A/S search andattack aircraft.

ElleAttL

71.134 Figure 2-21.LAMPS helicopter (SH-2F).

33 INTRODUCTION "F0 SONAR

Among the weapons that can he launched from fixed-wing aircraft and the Sil-2E SEASPRITE, an aircraft arethe homing torpedo and the the LightAirborneMulti-PurposeSystem nuclear depth charge. ( LAMPS) helicopter. Both are integral parts of PATROL PLANE ASW search-attack units.

Patrolplanesareland-based,long-range, TheS-3AVIKING (fig. 2-20) is a mult ngineaircraftusedfordetecting, carrier-based jet-powered A/S search atul attack tracking, and attacking enemy shipping and aircraftDetection equipment includes radar, submarines. ESMreceivers,sonobuoys, and MAD gear. The P-3 ORION (fig. 2-19) isthe Navy's 0 rd na n cc. eq uipmentincludestorpedoes, principal patrol plane. To carry out its primary rockets, and depth bombs. mission of locating and attacking submarines, it hasavarietyofsensors,includingradar, The SI-I-2F (LAMPS) (fig. 2-21) helicopters sonobuoys, magnetic anomaly detector (MAI)), are found aboard a variety of ASW ships. They and electromagnetic intercept (ISM) equipment. providetheshipwith an extended antiship ORION's armament includes torpedoes, rockets, missiledefense and ASW system.Detection depthbombs,air-to-surface missiles, and equipmentincludesactiveandpassive conventional bombs.Italso can be used for sonobuoys, magnetic anomaly gear, and radar. aerial mining. Secondary functions include ali-weather search ANTISUBMARINE AIRCRAFT andrescue, planeguard duties,gunfire observation,personneltransfer,andvertical Shipboard aircraft used for antisubmarine replenishment. Weapons include torpedoes and ( A SW ) m issionsare theS-3AVIKING depth bombs.

3 9

34 CHAPTER 3

PHYSICS OF SOUND

Sonar is an electronic device that uses sound diagramedasthough seenincross section. energytolocate submerged objects such as Observe that the waves are a succession of crests submari .es.Sonar equipment may be either and troughs. The wavelength (Icycle) is the active or passive. Active sonar transmits sound distance from the crest of one wave to the crest energyintothe water and depends on the of the next wave. The amplitude of a transverse returning echoes bouncing off the targetto wave is half the distance, measured vertically provide bearing and range information. Passive fr:)m crest to trough, and serves to indicate the sonar uses sounds originated by the target (such intensity of the wave motion. as screw cavitation, machinery noises, etc.) to determine Sound waves varyin length according to bearing information. This chapter their deals with sound and its behavior in seawater. frequency. A soundhaving a long wavelength is heard at a low pitch; one with a Sound travels in the form of waves which short wavelengthis heard at a high pitch. A may be classified as transverse or longitudinal. A complete wavelength is called a cycle, and the transverse wave is one in which the particles of number of cycles per secondis the sound's the medium through which the wave is passing frequency. move atrightangles vertically to the wave's Frequencies are now measured in the Hertz direction. In a longitudinal wave, the particles system, 1 hertz (Hz) being equal to 1 cycle per move back and forth along the wave's direction second. Frequencies of 1000 cps or moreare oftravel,resulting in compressionand measured in kilohertz (kHz). Normally, sounds rarefaction of the wave. below 20 Hz or above 15 kHz are beyond the An example of a transverse wave is a water humanhearingrange.Betweenthesetwo wave. Throw a stone into a pool. A series of frequencies is the average human audiblerange. circularwavestravelsawayfromthe In short, sound is the physical cause ofyour disturbance.Infigure3-1,suchwaves are sensation of hearing; anything that you hear isa sou nd .

REQUIREMENTS FOR SOUND Before sound can be produced, three basic elements must be present. These elementsare a source of sound, a medium to transmit the sound, and a detector to hear it. In the absence of any one element, there can beno sound. You may recall the experiment in whicha bell was placed inside a jar containinga vacuum. You could see the bell striking, butyou could 71.19 hear nothing because there was no medium to Figure 3-1.Elements of a wave. transmit sound from the bell to you. What about

35 INTRODUCTION TO SONAR Detector

The detector acts as the receiver of the sound wave. Becauseit doesn't surround the source of the sound wave, the detector absorbs only part of the wave's energy and requires an amplifier to boost the signal's energy to permit reception of weak signals.

THE EAR AS A SOUND DETECTOR.The 71.18 limits of human hearing are determined by two Figure 3-2.The three elements of sound. interactingphysical variables, frequency and intensity, and several other conditions that are the third element, the detector? You may see a dependent on the individual variables (including age,stateofhealth,attention,andprior source(such asanexplosion)apparently exposure). The limits of hearing, however, are producing a sound, and you know the medium normally between 20 Hz and 20 kHz for young, (air) is present, but you are too far away to hear healthy persons, provided the upper and lower the noise. So far as you are concerned, there was nodetector frequencies are sufficiently intense. For healthy, and,therefore, no sound. For middle-aged persons, however, the upper limit purposes of this text, we must assume that may liebetween 12 sound can exist only when an auditory vibration and 16kHz,the low-frequency Lhreshold remaining about 20 Hz. is caused by a source, is transmitted through a For purposes of this text, sounds capable of medium, and is heard by a detector. Figure 3-2 being heard are called sonics. Sounds below 20 illustrates this assumption. The bell vibrates on being struck, thus acting as a sound source. The Hz are called subsonics, and those above 15 kHz vibrating bell moves the particles of airthe are known as ultrasonics or supersonics. The term "ultrasonic"inerelyrefers toacoustic mediumin contactwithit. And the sound phenomena above the level of human hearing. A waves traveltotheear, which actsas the detector. 15-kHz vibration might be "ultrasonic" for the average 60-year-old person. Early active sonar equipments transmitted Source ultrasonic sounds through the water. Along with other sounds, they received echoes of these Any object that moves rapidly to and fro, or ultrasonicsounds andconverted them into vibrates, and thus disturbs the medium around it audible ones. Modern active sonars transmit may becomeasoundsource.Bells,radio sounds within the audible range. Because these loudspeakerdiaphragms,andstringed transmissions are very high tones, however, the instruments are familiar sound sources. equipment converts them into lower ones better suited for listening. Medium The human ear is a good sound detector. It can detect a wide range of frequencies but does not respond equally well to all of them. Figure Soundwavesarepassedalong bythe 3-3 illustrates the variation in the amount of material through which they travel. The density power that is barely audible to the average ear at of the medium determines the ease, distance, different frequencies.Itis evident from this and speed of sound transmiion. The greater the chart that the ear is most sensitive to frequencies density, the greater the speed of sound. The in the range from about 1000 Hz to 2000 Hz. speed of sound through water is about four The average person finds an 800-Hz notea times that through air and through steel itis rather pleasant one tu listen to for long periods abou:. 15 times greater than through air. 4 iof time. In underwater echo ranging equipment,

36 Chapter 3PHYSICS OF SOUND temporarily is paralyzed by very loud signals so RELATIVE POWER FOR AUDIBLE SOUNDS that you may not hear the weaker signals that follow. 100,CCA.: 3.Your ear has the property of pitch AVERAGE discrimination. This characteristic will aid you in FREQUENCY 10,000 SENSITIVITY selecting an echo from the background of noise OF HUMAN EAR 1000 and reverberation. 00 Heavy gunfiremay causepermanent 10 deafness or other injury to your ears. Use ear protectors or cotton when near gunfire, and take 100 1000 10000 everypossibleprecautiontoprotectyour FREQUENCY HERTZ hearing. As a Sonar Technician, you are essential to the successful mission of your ship. Your 71.46 ability to operate the sonar depends on the Figure 3-3.Frequency sensitivity of the human effectiveness of your hearing. ear. SOUND WAVES the echo frequency commonly is converted to an 800-Hz note. Sound waves are longitudiral or compression Neverturnupthevolumeonsonar waves, set up by some vibrating object such as a equipment so that echo sounds are louder than sonar transducer. In its forward movement, the necessary. One reason is that the ear is not a vibrating transducer pushes the water particles sensitive detector of relative changes in sound lying againstit,producing an area of high intensity. An increaseor decrease of about pressure, or compression. one-fourth of the total power must take place before the ear notices any difference. On thebackwardmovementofthe transducer, the water particles return to the area An intensely loud sound slightly paralyzes fromwhichthey weredisplacedduring the ear, reducing its ability to hear low-intensity compression and travel beyond, producing an sounds that follow immediately. This effect is area of low pressure, orararefaction. The similar to one you probably have experienced compression moves outward by pushing the with light. If you look into a very strong light, water particles immediatelyinfront of the your eyes are blinded momentarily. compressedparticles. The rarefaction follows The ear is a sensitive detector of change in tit: compression, transferring the pull produced pitch. An average person can tell when sounds bythe backward movement to the particles differ afew hertz in pitch, even though they immediately ahead. The next forward movement cannot detectthe changeinintensity. This of the transducer produces another compression faculty is known as pitch discrimination. It is a and so on. In figure 3-4 the compressions are great help in selecting from a background of represented by dark rings. As the sound waves reverberationsasubmarine echo of slightly spread out, their energy simultaneously spreads different pitch, that is, one with doppler. through an increasingly large area. Thus the waveenergybecomesweakerasdistance Here's a summaryofyourear's characteristics: increases. Another way of representing the actions of a I.Your ear does not readily detect small sound wave is illustratedinfigure3-5. relative changes in sound intensity.Itis not Compressions are shownashills abovethe sensitive to high and low audible frequencies. reference line, and rarefactions as valleys below 2.Your ear is sensitive to the 800-Hz note it. The wavelengthisthe distance from one for which sonar equipment is designed. Your ear point on a wave to the next point of similar

37 IL 4 2 INTRODUCTION TO SONAR

Density

Perhaps you've heard people speak ofa RAREFACTION heavy fog as being "thick aspea soup." This murky condition would be a dense fog caused COMPRESSION IP by the atmosphere beingfilledwith small particles of water called vapor condensation.A TRANSDUCER fog-filled atmosphere is heavier (because ofthe weight of the water particles in it) thana clear atmosphere. The measure for this "thickness" of a substance is called density, and is defined as "weight perunit volume."In the study of general physics, density of any substance isa comparison of its weight to the weight ofan equal volume of pure water. Because of the salt content (salinity) of seawater, it hasa density greater than that of freshwater. Density is also an indication of the sound transmission characteristics of a substance,or medium. When a sound wave passes througha WAVE LENGTH medium,itistransmitted from particleto particle. If the particles are loosely packed(as theyareinfreshwaterascompared with seawater), they have a greater distance tomove totransmitthe soundenergy.Duringthe movement, time is consumed, and the overall result is a slower speed of sound ina less dense medium. 4.221 Figure 3-4,Longitudinal waves. Density and elasticity are the basic factors that determine sound velocity. The formulafor determining velocity is: co m p r essi on. Thechangeoccurring in compression and rarefaction in the space of 1 wavelength is called a cycle. C

Frequency

where C equals velocity, E equalsthe medium's Thefrequency of a sound waveis the elasticity, and p equals the medium'sdensity. number of vibrations per second produced by Variations in the basic velocity of thesoundsource. A sonar sound in the transducer,for sea are caused by changes in watertemperature, example, may transmit on a frequency of 5 kHz, pressure, and density, as will be seen in the or5000vibrationspersecond. Mdtionis section on sound propagation. In impartedtothe freshwater of soundwave by the 65°F. sound velocity is approximately4790 back-and-forth movement of the particles of the feetper second(fps).Inseawater, velocity medium,ineffect passingthe wave along, depends on pressure and temperaturein addition although the particles themselves havevery little to salinity. For all practical actual purposes, you can movement. The wave, however, may assume that sound travels at a speed of 4800fps travel great distances at a high rate of speed. in seawater of 39° F.

38 4 3 Chapter 3PHYSICS OF SOUND

-a-WAVELENGTH thetoneofa sound.Withtheproper combinationofcharacteristics,thetoneis pleasant.Withthe wrong combination, the sound quality degenerates into noise. &LITUDE Pitch

An objectthatvibrates many times per second produces a sound with a high pitch, as in COMPRESSION RAREFACTION the instance of a whistle. The slower vibrations of the heavier wires within a piano cause a low-pitchedsound.Thus,thefrequency of Figure 3-5.The sound wave. 71.21 vibration determines pitch. When the frequency Wavelength is low, sound waves are long: when it is high, the waves are short. If a sonar transducer vibrates at the rate of 25,000vibrationspersecondandifthe temperature is 39°F, the first wave will be 4800 Intensity feetawayatthe end of thefirstsecond. Between the transducer and the front of this Intensity and loudness often are mistakenly wave there will be 25,000 compressions. Thus, interpreted ashavingthesamemeaning the wavelength (thatis, the distance between Although they are related, they are not the points of similar compression) must be 4800 same. Intensity is a measure of a sound's energy. 25,000, or 0.192 foot, because there are 25,000 Loudnessistheeffectof intensity on an compressions extending through a distance of individual in the same manner that pitch is the 4800 feet. The wavelength always can be found effect of frequency.Increasing the intensity if the frequency and the velocity are known. causes an increase in loudness but not in a direct Formula: proportion. To double the loudness of a sound Velocity. requires about a tenfold increase in the sound's Wavelength Frequency intensity. Suppose the wavelength is 0.4 foot and the frequency is 12 kHz. What is the velocity? Quality 0.4Velocity. 12,000 The quality of a sound depends on the complexity of its sound waves. Most sounds Expressed another way, velocity = 0.4 x 12,000 consist of a fundamental frequency (called the = 4800 fps. If the wavelength and velocity are first harmonic) plus several other frequencies known, the frequency can be found in a similar that are exact multiples of the fundamental. The manner. fundamental is the lowest frequency component 4800. of the sound wave. By combining different 0.4 = Frequency fundamentals in suitable proportions, a tone can be built up to a desired quality. Musical tones Or, frequency = 48000.4 = 12 kHz. are produced by regular vibrations of the source; when the source vibrates irregularly, the sound is CHARACTERISTICS OF SOUND called noise. By sounding together the proper organ pipes, the tone of any vowel sound can be imitated.Ontheotherhand,drawing a Sound has three basic characteristics: pitch, fingernail across a blackboard only creates a intensity, and quality. Together they make up noise.

4 4 39 INTRODUCTION TO SONAR

MEASUREMENT OF SOUND watts, or from 1000 watts to 100,000 watts, it still is a 20-db increase. Throughout your Navy career as a Sonar Examine table 3-1 again, and take particular Technician, you will be using decibelsas an note of the power ratios for source levels of 3 db indicator of equipment performance. Power and 6 db (also 7 and 10 db). Itcan be seen that output and reception sensitivityof a sonar to increase a sonar's source level by 3 db, it is equipment are measured in decibels, whichare necessary to double the output power. As a used to express large power ratios. typical example, if the sonarsource level drops In the decibel system, the reference level is from 140 db to 137 db, thesonar has lost half zero decibel (0-db), which is the threshold of its power. Any 3-db loss, no matter whatthe hearing. The pressure level, or signal strength, of sourcelevel, means loss of half the former underwater sounds is compared to the 0-db level power. and is given either a positive or a negative value. Now let's see what is required to increasea Sonar receivers are capable of detectingsounds sonar's range. To double therange of a sonar having a signal strength below the 0-db level.In requires a source level increase of approximately such instances, the signal is givena minus db 27 db. This power increaseis equivalent to value. about 500 times, which obviously is impractical. The reasonfor using the decibel system By another method, such as increasing receiver when expressing signal strengthmay be seen in sensitivity,the rani4ecan be increasedfairly table 3-1. It is much easier to say thata source easily, although it may not be doubled. level has increased 50 db, for example, thanit is So far we have discussed the decibel mainly to say the power output has increased 100,000 in relation to power output, but the decibel times. The amount of power increase also or decrease is usedtodeterminereceiversensitivity. fromareferencelevelis the determining Receiversensitivity is measuredinminus factornot the reference level itself. Whether numbers,whichrepresentthenumber of power output is increased from I watt to 100 decibels below a reference level that signalcan be detected bythe receiver. The larger the negative number, thebetter the Table 3-1.Decibel Power Ratio Equivalents sensitivity. Although the range would not be doubled,it is morepractical,forinstance,toincreasea receiver's sensitivity from 112 db to 115db than itis to double the outputpower of the sonar Source Level (db) Power Ratio transmitter. Also, itis not always necessary to increase the sensitivity of the receiveritself. An 1 . 1.3 effective increase of several decibelsmay be 3 = 2.0 achieved if local noise levelscan be reduced in 5 = 3.2 such sources as machinery, flownoise, crew 6 . 4.0 noise, etc. 7 . 5.0 10 . 10 NOISE 20 = 100 30 = 1000 40 = 10,000 50 = The most complex soundwave is one in 100,000 whichthesoundconsists 60 = 1,000,000=10' ofnumerous 70 = 10,000,000=107 frequencies across a wide band. Sucha form of 100 = 101D sound is called noise because it hasno tonal 110 = 10" quality. The source of severaltypes of noises 140 = 10" may be identified easily, however, because of the standard sound patterns of thenoises. Ship noise, for instance, consists ofmany different 40 Chapter 3PHYSICS OF SOUND name implies, itis a function of temperature. BACKGROUND This noiseis created by the motion of the NOISE molecules of the liquid itself and is difficult to measure.

ISELF AMBIENT SURFACE AGITATION.Fora sizable region above the residual minimum noise, the

EQUIPMENT I 1 BIOLOGICAL ambient noise levels appear to be related to the surfaceagitation.Usually,agitationof the surface of the seais measured as sea state. CREW SEA I Surfacewindspeed, however, ordinarilyisa more reliable measure of expected ambient noise FLOW 1 MISCELL A NEOUS-H than sea state. As the wind rises, the surface becomes more and more agitated, causing the

MACHINERY 1 UNIDENTIFIED ambient noise level to rise. Normally noise levels in this region are associated with what is called sea noise to distinguish them from other noises PROPULSION which really arc not caused by the sea itseP. A heavy rain, for instance, will add greatly to the AUXILIARY ambient noise.

Flow Noise 71.116 Figure 3-6.Noise sources. As an object moves through water, there isa relativeflowbetweentheobject andthe medium. This flow is easiest to understand by sounds mixed together. You may be unable to assuming that the object is stationary and that distinguish a particular sound but, on the whole, the water is moving past the object. If the object you can recognize the sound source as a ship. is reasonably streamlined, its surface is smooth, Some noise sources are shown in figure 3-6. The and if itis moving very slowly, a flow pattern sources of many noises detected by sonar have known as laminar flow is set up. Such a pattern not yet been identified. Explanations of sonie is shown in view A in figure 3-7, where the lines kinds of noises that have an adverse effecton a sonar operator follow.

AMBIENT NOISE

Ambient noise is background noise in thesea that isduetonaturalcauses.Different phenomenacontributetotheambient background noise. Many of the sourcesare known and their effects are predictable, but many are still unknown. From this unwanted background noise, the sonar operator must be ableto separate weak or intermittent target noises. In general, the average operator requires a targetsignalstrengthof 4dbabove background noise. 71.22 THERMAL NOISE.The absolute minimum Figure 3-7.Patterns of flow noise: Alaminar noise in the ocean is called thermal noise. As the flow; Bturbulent flow.

41 4 6 INTRODUCTION TO SONAR represent the paths followed by the water as it flows around the object. If the flow is laminar, alllines are smooth. Although laminar flow produces little, if any, noise, it occurs onlyat very low speedsperhaps less than I or 2 knots. If the speed of the water is increased, whorls and eddies begin to appear in the flowpattern, asseeninpart Binfigure3-7, and the phenomenon iscalled turbulent flow. Within these eddies occur points where thepressure is widely different from the staticpressure in the medium. Thus we have, in effect, a noise field. If a hydrophone is placed in such a region, violent fluctuations of pressure willoccur on its face, WATER FLOW and flow noise will be observed in thesystem. As pressures fluctuate violently atany one 71.23 pointwithintheeddy, theyalsofluctuate Figure 3-8.Blade tip cavitation. violently from point to point inside the eddy. Moreover, atany giveninstant, the average pressure of the eddy as a whole differs but Cavitation slightly from the static pressure. Thus,very little noise is radiated outside the area of turbulence. Cavitationisproduced whenever asolid Hence, although a ship-mounted hydrophone object moves through the water at a speed great may be in an intense flow noise field, another enough to create air bubbles. Aftera short life, hydrophone at some distance from the ship may most of thebubblescollapse.The sudden be unable to detect the noise at all. Flow noise, collapse of the bubbles causes the acoustic signal then, is almost exclusively a self-noise problem. known as cavitation noise. Each bubble,as it Actually, not much information is known collapses, produces a sharp noise signal. about flow noise, but general statementsmay be Because the onset of cavitation is related to madeaboutitseffecton a shipborne thespeedof the object,itislogicalthat hydrophone: (1) It is a function of speed witha cavitationfirstappearsatthetipsof the sharp threshold. At very low speeds there isno propeller blades, inasmuch as the speed of the observable flow noise. A slight increase in speed blade tips is considerably greater than__ speed changes the flowpatternfrom laminarto of the propeller hub. This phenomenon known turbulent, and strong flow noiseis observed as blade tip cavitation is illustrated in figure 3-8. immediately. Further increases in speed step up As the propeller speed increases, a greater the intensity of the noise. (2) It is essentiallya low-frequency noise. (3) It has very high levels portion of the propeller's surface is moving fast within the area of turbulence but low levels in enough to cause cavitation, and the cavitating the radiated field. In general, the noise field is area begins to move down the trailing edge of strongest at the surface of the moving body, the blade. As the speed increases further, the decreasing rapidly as you move away from the entirebackfaceof theblade commences surface. cavitating, producing what is knownas sheet cavitation. This form of cavitation is shown in As thespeedof the ship or objectis figure3-9. Cavitation noiseis referred to as increased still further, the localpressure drops hydrophoneeffects.Theamplitudeand lowenough atsomepointstoallowthe frequencyofcavitationnoiseareaffected formation of gas bubbles. This decreasein considerably by changingspeeds. Cavitation pressure represents the onset of cavitation. The noiseversus speedataconstant depthis noise associated with this phenomenon differs diagramed in figure 3-10. The curves shownare from flow noise. idealized; they do not represent any particular 4 7 42 Chapter 3PHYSICS OF SOUND submarine. Note the great difference in noise level caused by the addition of only 20 turns, from 90 rpm to 110 rpm. At 90 rpm there is no cavitation; the noise level is due to flow noise and background noise. At 110 rpm cavitation has started, and the noise level has gone up many decibels, with a peak amplitude at about 400 Hz. As speedisincreased further, the amplitude peak tends to move toward the lower frequencies. The amplitude increases at a lesser rate, but covers a broader frequency band. The curves are also characteristic of a submarine on the surface and of surface warships although the amplitude levels may be different. WATE R FLOW 3, Cavitation noise versus depth at a constant speed (170 rpm) is shown in figure 3-11. The upper curve is the same as the upper curve in figure 3-10. As the submarine goes deeper, the 35.50 cavitation noise decreases and moves to the Figure 3-9.Sheet cavitation. higher frequency end of the spectrum in much

the same manner as though speed had been 1,EQUENCY (HERT Z1 500 )000 5000 10 COO decreased. This decrease in noise is caused by 60 the increased pressure with depth, which tends OEPTR.55FT to compress cavitation noise. The curves are not exactly the same as those shown in figure 3-10, 170 RPM but the similarity is readily apparent. 150 RPM .30 RPM 11ORPM Machinery Noises

Machinery noise is produced aboard ship by 90 RPM the main propulsion machinery and by any or all of a large number of auxiliary machines that 71.24 may or may not be connected with the main Figure 3-10.Speed effect on cavitation noise. propulsion system. Machinery noise usually is produced by rotating or reciprocating machines. Most noise of this type is generated by dynamic imbalanceoftherotatingportionof the FREQUENCY (HERTZ) 100 500 1000 5000 10,000 machinery that causes a vibration within the 60 Rill :170 RPM machine.Suchavibrationmay thenbe 10424. transmitted through the machine mounts to the , hull from where it is radiated into the water as '53 90 NIMItiminft/IIN/agn55 FT, acoustic energy. 0M-1 100 FT , 200 FT 04 20 raja Shipboard Noise 300 FT. In addition to the machinery discussed so far, there are many other shipboard noise sources over which you probably will not have any control. Some of the noise sources are fire and 35.51 flushing pumps, air compressors, refrigeration 3-11.Depth effect on cavitation noise. 4gigure 43 INTRODUCTION TO SONAR

machinery,airconditioningsystems.diesel which are similar to whales, emita whistling generators, gasoline pumps, blower motors, and sound like a porpoise but cIearer in tone. portablepowertools. Any (orall) of the The preceding examples of marine life noises aforementioned equipment may be operating at are just a few that you will encounter. Do not any onetime, adding greatlytothe noise let the strange sounds misleador distract you. A radiated by the ship and therefore entering the valid target may be just beyond the whale sonar receiver. you If the combination of these arelisteningto.Availabletapes andfilms noises becomes too great for effectivesonar describemanybiologicnoises.AB Sonar search. ask your watch supervisor to request the Technicians should review these tapes and films OOD tosecure allnonessential equipment. periodicallytomaintain proficiencyintheir Another noise source is circuit noise, generated recognition of sounds. within the sonar equipment itself, Thisnoise may be in the form of' a 60-hertz hum, staticlike noises from electric cables due to improper cable Torpedo Noise shielding, or leakage currents from othersources enteringthereceiverstages. Torpedo noiseis distinct from all others. Unlike ambient When a torpedo is fired from noise, however, this type of' generated noisemay a submarine, the be controlled. first indication might be the sound ofescaping air, quickly followed by a propellerlikenoise. Marine Life The rhythm is too rapid for the beatsto be counted (as you can count those ofa ship's A sonar operator may hearmany strange propeller), and it increases swiftly in intensityas sounds during his time on watch. He itapproaches, resembling the whine ofa jet may have engine, but not as high pitched. to listen to (and try to identify) thesource of w h is tles,shrieks,buzzes, pings,knocks. cracklings,andotherstrangenoisesnot UNDERWATER SOUND PULSE ordinarily associated with thesea. Most of these noises probably come from different speciesof Now that you know something of the theory fish,but onlyafew have been identified of sound, you are ready to takea closer look at positively. Following are descriptions ofa few what happens to an underwater sound pulse. marine life noises. To gain thefullbenefit of echo ranging Porpoises give out a whistling sound and sonar equipment, you must be able to transmit sometimesa soundlike achuckle. These an underwater sound pulse and recognize the mammals are found inall ocean areas of the returning echo from a target. Detectionof the world.(Submarinehydroplanes and rudders echodependsonitsqualityandrelative sometimes also give off a whistling sound.) strength.comparedwiththestrengthand character of other sounds that tendto mask it. Snapping shrimp are common around the Sonar Technicians must know (I) whatcan world between latitudes 45°N and 45°S,usually weaken sound asittravels through water, (2) in waters less than 30 fathoms deep. Asyou what conditions in the approach a bed of snapping shrimp, sea determine the path you hear a and speed of sound. and (3) what objectsaffect buzzing sound. As you go closer, the sound the strength and character of the echo. resembles fat sizzling on a fire, then becomes similar to that given off by burning brush. TRANSMISSION LOSSES Whales, which are found in alloceans, give offavarietyof sounds. including knocks. As a sound pulse travels outward fromits groans, pings. and one resembling a swinging source, it becomes weaker and weaker. Much of rusty gate. The knocking sound of thesperm its energy is lost because ofsea conditions and whale resembles the noise of hammering.Sperm distance. Three factors directly related whales and other large species seldom to sound are heard transmission losses aye divergence,absorption, in waters shallower than 1 00 fathoms.Blackfish. and scattering. The latter twoare referred to as 44 Chapter 3PHYSCIS OF SOUND

atten uationlossandaredependenton reflected away from its direction of movement transmissionfrequency.Divergencelossis and is lost. The reflection losses to the water are independent of frequency. knownasscatteringlosses.Some ofthe scattered energy is reflected back to the sonar Divergence receiver and is then called volume reverberation (discussed later in this section). When a sound wave is projected from a point source, it assumes a spherical shape, spreading REFLECTIONS equally in all directions. This spreading is called divergence; and the further the wave travels, the When a sound wave strikes the boundary more energy it loses. The energy lost by a sound between two mediums of different densities, the wave due to spherical divergence is inversely wave will be reflected, just as light is reflected proportional to the square of the distance from by a mirror. Some of the energy will be lost, but its source, or 6 db each time it doubles. most of it will be reflected at an angle equal to In shallow water areas,the surface and the angle of incidence. The angle of incidence is bottom are boundaries that limit the vertical the angle, with respect to the perpendicular, at divergence of the sound wave. Consequently, the which the wave strikes the boundary. According expanding wavefront is cylindrical, rather than tothephysicslawofregularreflection spherical, in shape. Cylindrical spreading loss is (reflection from a smooth surface), the angle of only half that of a sphere, or 3 db each time the reflection equals the angle of incidence. distance is doubled. Spreading loss at close range isveryhigh, but beyond about 2000 yards Reflection takes place whenever the sound the loss becomes less significant. hitsthe boundary between sea and air(sea surface) and between sea and bottom, and when it hits a solid object, such as a submarine. The Absorption amount of energy reflected depends on the object's density, size, shape, and aspect. More In the topic on sound waves, you learned energy is reflected by a submarine broadside to how a sound pulse moves through water. The the sound beam than by one that is bow on. repeated compressions and rarefactions of the sound wave causes the water molecules to move back and forth, thus passing the sound wave Surface Effect along. An old saying goes: "You can't get something for nothing." In our illustrative case. Becausethedensity of waterisseveral energy is lost (in the form of heat) by the sound hundred times that of air, practically all of a pulseinitseffortstocompress thewater. sound waveisreflected downward whenit Energy lost to the medium inthis manner is strikes the surface boundary. This effect is true called absorption loss. only when the surface is quite smooth, however. When the surface is roug.h, scattering takes place. Scattering Bottom Effect Besideslossescausedby divergence and absorption, a sound wave loses energy due to the The bottom of the sea reflects sound waves, composition of the medium through which it too.In deep water, this aspect need not be passes. Composition of the sea naturally varies considered; but,inwaters of less than 100 from ,place to place and from time to time. In fathoms,thesound may beunwantedly general,however,seawatercontainslarge reflected from the bottom. Other considerations amounts of minute particles of foreign matter being equal, transmission loss is least over soft and many kinds of marine life of all shapes and mud. Over rough and rock,' bottoms. the sound sizes. Each time the sound wave meets one of is scattered,resulting in strongbottom these particles, a small amount of the sound is reverberations.

45 So INTRODUCTION TO SONAR

REVERBERATIONS moving farther and farther from thesource as You probably are acquainted with the effect the sound travels. If the surfacewere perfectly in an empty room where your voiceseems to flat,this sound energy would be reflectedas echo all around you as you talk. Afteryou stop though from a mirror, and would bounceaway talking, the sound continues to bounce around from the source in accordance with thelaws of the room from wall to wall until it finally is reflection.Butthe surfaceisnot perfectly absorbed by the walls and the air. The sound smooth, and each wavelet tendsto reflect the level in the room while you are talking is higher sound in all directions. Some reflected sound thannormalbecauseofthereverberation returnstothe hydrophone, addingtothe effects. The same effects can also be observed in reverberation. the ocean. Reverberation in the ocean usually is dividedintothreecategories.Theyare Bottom Reverberation reverberations from the mass of water, from the surface, and from the bottom. The following discussion on reverberations In general, reverberation effects fromboth the mass of water and the surfaceare small may seem like a repetition of the topicon compared to bottom reverberation. The reflections, but the two phenomenaare not the bottom is usually much rougher than the surface.Thus, same. Although reverberations are reflections, all moreof reflections do not become reverberations. thesoundisreflectedinother All directions than those expected ofa reflecting the processes contributing to reverberationare randomin mirror. If the water is fairly deep,no bottom nature,withtheresultthat reverberation occurs for quite reverberation amplitudes varyover wide limits. some time after Moreover, reverberation level is proportional to the pulse, because the sound must be giventime to reach the bottom and be reflected.Normally, source level and to pulse length. Another point a to remember is that, when you sharpriseeventuallyoccurs in the are in company reverberation level after thesourc s ic -it off, with another ship, you may hearreverberation effects from her sonar in additionto your own. REFRACTION Volume Reverberation If there were no temperature differencesin Reverberation from the mass of water is the calledvolumereverberation,which sea, a sound wavewould travel was approximately mentionedinthediscussion onscattering. ina straightline because the Suppose a short pulse of sound issent out from speed of sound would be roughly thesame at all depths. As indicated in figure 3-12, the astationaryunderwatersource,which is sound immediately replaced by a listening hydrophone. wouldspreadandbecomeweakenedby attenuation at a relatively constant As the pulse of sound travels through thewater, rate. it encounters various particles that reflectand Unfortunately, however, the speed of sound scatter the sound. Because almost all of these is not the same at all depths.The velocity of particles are much smaller thana wavelength of sound in seawater increases from 4700 the sound, they do not reflect the sound feet per as a flat secondto5300feetpersecondasthe mirror reflects light. Instead, they absorbenergy temperature increases from 30° to 85° F. As from the sound wave and reradiate this will enerey in be seen later in the chapter, salinityand pressure all directions. Some reradiatedenergy from each also affect sound speed, but their effects particle returns to the hydrophone usually at the source aresmallinrelationtothelargeeffects location and is heard as a gradually fadinetone commonly produced by temperature at the same frequency as the source. changes. Because of the varyine temperaturedifferences Surface Reverberation in the sea, the sound does not travelin a straight line. Instead, it follows curved paths, Some of the sound energy from the resulting in source bending, splitting, and distortion ofthe sound strikes the surface, the point of impineement beam.

46 5 1 Chapter 3PHYSICS OF SOUND

HIGH TEMPERATURE

MAXIMUM ECHO RANGE

71.26 Figure 3-12.- Sound travel in water of constant 71.27 Figure 3-13.A refracted sound beam. temperature.

When a beam of sound passes from one sound: divergence, attenuation (absorption, and medium in which its speed is high (suchas warm scattering).reflections,reverberations, water) into one in which its speed is low (such as refraction,andquenching.Now, wemust cool water), the beam isrefracted (bent). A consider the structure of the sea as an acoustic sound beam bends away from levels of high medium and learn the effects of this structure temperatures and hid sound velocity, and bends on the transmission of sound. toward levels of low temperature and low sound velocity. Figure 3-13 illustrates the refraction of STRUCTURAL CONDITIONS a sound beam. As a result of refraction, the range at which a submarine can be detected by The speed of sound wave travel through the sound may be reduced to less than 1000 yards. water is controlled by three conditions of the This range may change sharply with changing sea: (I ) temperature, which takes the form of submarine depth. slopes and gradients; (2) pressure, caused by increased depth; and (3) salinity, or the salt QUENCHING content of the water.

In strong winds and heavy seas, the roll and Temperature pitch of the echo ranging ship make it difficult tokeep the sound directed on thetarget. Withpresentlyoperationalsonars, Additionally,theturbulenceproducesair temperature is by far the most important of the bubblesinthe water, weakening the sound factors affecting the speed of sound in water. waves. Occasionally this envelope of air bubbles Depending on the temperature, the speed of blankets the sound emitted by the transducer. sound increases with increasing temperature at Sonar operators cantell, by a dull thudding the rate of 4 to 8 feet per second per degree of sound, when the sound beam is being sent out change. Inasmuch as the temperature of thesea into air. This action is known as quenching, varies from freezing in the polar seas tomore than 85°F in the tropics, and may decrease by more than 30°F from the surface to depth of PROPAGATION OF SOUND IN THE SEA 450 feet, it is clear that temperature hasa great effect on the speed of sound. Remember: The We havediscussed thevariousbasic speed of sound increases when the temperature phenomena that cause power loss in transmitting of water increases.

47 or 2 INTRODUCTION TO SONAR

PRESSURE SAL1NiTY TEMPERATURE (PSI) (0 00) (F) 0 25005000 33 34 35 30 45 60 COmPOSITE

2000

u_) 4000

al 6000 LU0 8000

10,000 0 90 180 42 146 150 297 404.5 51248004900 5000 VELOCITY CHANGE vELOCITY (FT SEC) (FT SEC)

35.5 Figure 3-14.Nomal curves for pressure, salinity, andtemperature.

Pressure Composite Sound travels faster in water under pressure. Figure 3-14 shows reasonably normalcurves Pressure increases as depth increases,so the fortemperature,salinity, and pressure as a deeper a sound wave travels, the faster it travels. function of depth in the Pacific Ocean andalso Pressure effect on transmitted sound, although the resulting velocity structure. rather Itshould be smallincomparisontotemperature noted that the salinity variation playsa minor effects, cannot be neglected. The speed ofsound part in the form of the depth velocity increases about 2 feet per second each 100 curve. feet This effect is almost entirely evident in thefirst of depth. 500 feet below the surface. The temperature curve also shows wide variations in the top 500 Salinity feet.From2000feet,downward,the temperatureisnearly uniform asthe water Seawater has a high mineral content. Salt approaches the maximum density point at about content is spoken of as the salinity of thewater. 40°F. The pressure effect is represented bya The weight of the higher densityseawater is straightline as thevelocity increases linearly about 64 pounds per cubicfoot:that of with depth. freshwater is about 62.4 poundsper cubic foot. On the composite curve, it easilycan be seen This variation is the result of the saltcontent in the seawater. that the velocity in the top 2000 feetisa The overall effect of increasing the salinity somewhat skewed replica of the temperature of water is to increase the speed of curve. Below 2000 feetit follows closely the the sound, straight line gradient of the pressure which means that, when soundpasses through curve. water that varies in salinity, it travels faster in the saltier water. In the openocean, the values Depth/Temperature Effect of salinity normally lie between 30 and 35parts per thousand. In the region of rivers and other Except at the mouths of great rivers, where freshwater sources, the salinity valuesmay fall salinity may be a determinant, the path followed to levels approaching zero. The speed of sound by sound is governed by thewater temperature increases about 4 feet per second for eachpart and the pressure effect of depth. per thousand increase in salinity. Salinity hasa The pressure effectis always present and lesser effect on the speed of sound thandoes always acts in the same manner, tendingto bend temperature, but its effect is greater than that of the sound upward. Figure 3 15 illustratesthe pressure. 5 3 situation when the temperature does not change 48 Chapter 3PHYS1CS OF SOUND

beneath it,the water has a positive thermal gradient. Although this condition is unusual, it does happen andcauses the soundtobe refracted sharply upward. In certain areas of the RedSea,bet weenAfricaandArabia, temperatures of well over 100°F have been LOW PRESSURE recorded in depths exceeding 1mile. Moreover, thesalinityofthewaterinthoseareas approaches 30%, compared to between 3% and 4% in most ocean areas. When the sea grows cooler as the depth increases, the water is said to have a negative thermal gradient. Here the effect of temperature greatly outweighs the effect of depth, and the soundisrefracted downward. This common condition is illustrated in figure 3-17. If the temperature is the same throughout 71.29 the water, the temperature gradient is isothermal Figure 3-15.Pressure tends to bend the sound (uniform temperature). In figure 3-18 theupper beam upward. layer of water is isothermal: beneath this layer thetemperature decreases with depth. This temperaturechangecausesthetransmitted with depth. Even though the temperature does soundtosplitandbendupwardinthe not change, the speed of sound increases with isothermal layer and downward below it. depth, due entirely to the effect ofpressure, and the sound bends upward. Don'tforget: When notemperature Figure3-16 shows what happens when difference exists, the sound beam bends upward. temperature increases steadily with depth. When When the temperature changes with depth, the the surface of the seais cooler than layers sound beam bends away from thewarmer water.

71.30 71.31 Figure 3-16.Positive thermal gradient tends to Figure 3-17.Negative thermal gradient tends to bend the sound wave upward. 5 4 bend sound downward. 49 INTRODUCTION TO SONAR

intensity signal. On the ASW ship, ranges on submarinesarereducedgreatlywhenthe submarine dives below asharp thermocline. Often, the echoes received are weak and mushy. ISOTHERMAL SHALLOW WATER EFFECT.Echo ranging is difficult in shallow water because the sound is reflected from the bottom. When the ship is in shallow water and the ocean floor is smooth, the sound bends down from the surface to the bottom then back up to the surface, and againdowntothebottom. When the transmitted sound acts in this manner, there are spaces empty of sonar coverage into which a submarine can pass and be undetected. In figure 3-20 you will notice how a sonar contact ona submarine can belostwhen the submarine 71.32 enters the shaded area. Figure 3-18.Sound wave splits when temperature The shaded spaces in figure 3-20 are called is uniform at surface and cool at bottom. shadow zones. Contactisregained when the submarine enters the wave path again. As shown Unde7 ordinary conditions the seahas a in the illustration. contact is made at long range temperatrfe ;*.ructure similar to that in figure (point A). is lost (point 13). and is regained at 3-19.'11fistemperature structureconsists of shortrange(pointC).Note however that, three rats: A surface layer of varying thickness. withoutthereflection,the maximum range with uniform temperature (isothermal) ora would have been the short range at which the relativelyslight temperaturegradient:the contact was regained (point C). thermocline. a region of relatively rapid decrease The reason for the loss of contact at short in temperature: and the rest of the ocean, with range is shown at point D where the submarine slowly decreasingtemperature down tothe bottom. If this structure changes. the path ofa beam of sound through thc water also changes. SEA SURFACE LAYER DEPTH.Layer depth is the depth TEMPERATURE UNIFORM OR SURFACE LAYER from the surface to the top of a sharp negative CHANGING SLIGHTLY ISOTHERMAL OR gradient. Under positive gradient conditions, the WITH DEPTH "MIXED LAYER" layer depthisatthe WHEN TEMPERATURE depth of maximum UNIFORM temperature.Abovelayerdepth.the temperature may beuniform.Ifitisnot TEMPERATURE uniform, a positive or weak negative gradient DECREASING THERMOCLINE may be present. RAPIDLY

TEMPERATURE LAYEREFFECT.-- Layereffect is the REGION BELOW THE DECREASING partialprotectionfromechorangingand THERMOCLINE listening detection a submarine gains when it SLOWLY submergesbelowlayerdepth. Sometimes a submarine, diving through a sharp thermocline while taking evasiveaction,losesthe screw noises of the enemy ASW ship. Although usually 71.33 the pinging can stillbe heard. itis as a low Figure 3-19.Typical layers of the sea. ro 50 Chapter 3PHYSICS OF SOUND

Conditions for hearing are particularly a poor at SURFA,- the mouths of rivers. I 2.Better in winter than in summer. e 3.Better at night than in the middle of the 1r day, especially in spring andsummer. 4.Better in morning than in the afternoon, ,, ,... inspring and summer, butlittlechangeif \\ whitecapsarepresent.Inmanylocalities, however, conditions are better in the afternoon ' than in the morning because of the effect of BOTTOM,A prevailing wii;(1s that freshen in the afternoon.

DEEP WATER SOUND Pz,DPAGATION 71.28 Figure 3-20.Shallow water effect on transmitted From the preceding discussions, it can be sound. concluded that the behavior of the soundwave is influenced considerably by the structure of thesea. Most of our discussionsofar has passes beneath the sound. The distance at which pointed out the adverse effects on a sound beam contact is lost at short range depends on the in comparativelyshallowwatersay 100 depth of the submarine. Here is a rule of thumb fathoms or less. Now, let's examinesome of the for estimating a submarine's depth: phenomena that take place in very deep water. The range in yards at loss of contact is Direct Path roughly equaltothe depth of the Theoretically, if the sound waves were not submarine in feet. A contact lost at 300 affected by velocity gradients,allthe sound yards would thus be presumed to be waves would be straight lines and would travel in about 300 feet deep. a direct path at whatever angle they left the source. In actual practice, however, the sound Once the behavior of sound in seawater is beam follows a path, or paths, as determined by known, it is possible to predict sound conditions the sea condition at the time. in the sea. From the temperature gradient of the water, an experienced person can judge the Sound Channel maximumrangetoexpect. A new Sonar Figure 3-21 illustrates a combination of two Technicianis not expected to know how to gadients of equal slope, one nega tive andone predictsoundconditions,butheshould understand why results are poor one day and good another day. He should know what is meant by shadow zones, and the reasons why VELOCITY 0- RANGE sound does not travel in a straight line. He also should be abletodistinguish between poor } O- eq uipmen tadjustmentandpoorsound W conditions.

Following are some general conditions for hearing echoes. 71.34 I.Usually poor near coasts (50 miles)as Figure 3-21.Strong negative and strong positive compared to sea conditionsfartherout. gradients forming a sound channel. 5 6 51 INTRODUCTION TO SONAR

positive. Their junction is a point of minimum velocity.If a sound source transmits at this depth of minimum velocity, all of the sound --"---datiffike,_ beams that start in an upward direction will be bent back down, and those that start downward will be bent back up. When such a condition occurs, we have a sound channel. The depth of minimum velocity is the axis of the channel. In this symmetrical situation, a beam that starts out downwardwillriseashigh abovethe channel axis as it Ixent below it, and then will be bent downward again. Sound will remain in the 51.7 channel, as far as the channel exists, and will Figure 3-23.Bottom bounce effect. suffer very little loss as it progresses through the channel. Sound energy from a shallow source travels Although sound channels are ararityin downward in deep water. At a depth of several shallow water (under 100 fathoms), theyare thousand feet, the signal is refracted, due to always present in the deep water areas of the pressure, and returns to the surface at a range of world. The depth of the axis of the channel is about 30 miles. The surface zone is from 3 to 5 about 350 fathoms in the central Pacific and miles wide. somewhat over 500 fathoms in the Atlantic. In The sound that reaches the surface in the the polar regions. where the surface water is first convergence zone is reflected or refracted at materially colder, the axis of the channel lies the surface and goes through the same pattern nearer the surface. again. It produces a zone approximately 6 miles wide at 60 miles, and another 9 miles wide at Convergence Zone about 90 miles. Experienced Sonar Technicians are familiar with this convergence zone effect. Often they have picked up strong noise signals Another effect that is closely related to the from targets that appear suddenly. showup deep sound channelisthe convergence zone strongly for a few minutes, and then disappear. effect.The convergencezoneeffect, now A surface or near-surface contact detected in applied to long-range active sonar, has long been the first convergence zone will have about the used by submarine sonar operators. If the sound same signal strength as atarget detected at 3 source iS placed near the surface instead of near miles when no zone is present. Minimum depth the axis of the sound channel, the path followed required along the path of the sound 1,,.7m is by the sound beam looks somewhat like that in about 1000 fathoms. The usual requirc tis figure 3-11. 2000 fathoms for conductingconvergence zone searches. The minimum depth required is related tothesurfacevelocityof thesoundand VEL0CITY-1 RANGE*-- 30 MILES increases as the velocity increases.

BottomBounce

For long-range search in water depthsover 1000 fathoms, newer sonar equipmentinay operatein a bottombouncemode. The transducer is tilted downward at an angleso that the sound beam strikes the bottom andis 51.8 reflected back to the surface, as shown in figure Figure 3-22.Convergence zone. 3-23.

52 5 7 Chapter 3PHYSICS OF SOUND

LOW HIGH DOPPLER AND REVERBERATIONS u«,, oilIII 11((( ((« 111 1111 If( III 1111 1111III Earlier in this chapter you learned that,as a sound pulse moves through the water, it loses sonic of its energy to the water particles. The particles reradiate the energy in all directions. Part of the reradiated sound is returnedto the 71.37 sonarreceiver,andtheeffectknownas Figure 3-24.Doppler effect. reverberation isheard. The waterparticles become sound sources and, as your shipmoves through the water. doppler effect is noticed. The following example should help clarify doppler Because of the depression angle (150to effect for you. 450 ). the sound beam is affected less by velocity Your ship changes than are sound pulses transmitted inthe is underway at a speed of 15 normal mode. At great depths (2500 fathoms knots: sound velocity is 4800 feetper second: and greater) however, the sound beam usually sound frequency is 14 kHz. Thesonar is keyed, and I will be refracted before reaching thebottom, second later itis keyed again. During the thus producing a convergencezone effect. 1-second interval, the first pulse travels 4800 feet. When the second pulse is transmitted,it is only 4775 feet from the first one because the DOPPLER EFFECT ship has traveled 25 feet. Using the formulas given in onnection with wavelength,you can You probably are familiar with the changing easily determine that the apparent frequencyof thereverberations pitch of a train whistle as the trainpasses near fromaheadof you is you at high speed. As the train approaches. the approximately14.1Idly, whereas those from whistle has a high frequency. As the train behind your ship have a frequency of about 13.9 :Wes kHz. Reverberations from the beam will by. the frequency drops abruptly and becomesa have long, drawn-out sound. The apparent change in the same frequency asthe transmitted pulse frequency of a signal resulting from relative because the shipisneither going toward the motion between the source and the receiver is particles nor away from them. Thedoppler known as doppler effect. Figure 3-24 illustrates effect of reverberations is illustrated in figure doppler effect. 3-25. To determine echo doppler. theSonar Technician compares the tone ofa target echo Each sound wave produced by the whistle is to the tone of the reverberations. given an extra "push- by the motion of the train.As thetrain comes toward you,the resultant effect is an increase in pitch, caused by No Doppler compression of the waves. As the trainmoves away from you, the sound waves are spread Consider the echo from a submarine that is farther apart. resulting in lower pitch. neither going away from nor toward the sound Although a stationary receiver was used for beam.Iteitheris stopped or is crossing the illustrative purposes, the same effectscan be sound beam at a right angle. If the submarine is in either of these situations, it reflects the observedif the receiverismoving towarda same stationary source. sound as the particles in the water, and itsecho has exactly the same pitch as the reverberations, Because doppler effect varies inversely with whichmeansthesubmarineechohasno the velocity of sound. the effect is much less doppler. Therefore, whenever the pitch ofthe marked in the sea than it is in the air. Doppler submarine echo is the same as the pitch ofthe can, however, be noted by the Sonar Technician reverberations. you know that the submarine is if he listens carefully. stopped or that you are echoing off its beam.

53 0r 8 INTRODUCTION TO SONAR and you would report "No doppler." Figure 3-26 illustrates a "No doppler" situation. ----._ __.____------REVERBOATIONS THE SAME 14 0 kHz Doppler Up i------cr------,*\.,,N 's / /------1-1 \ Suppose the submarine is coming toward the / ------\ .Z---_-_--. echo ranging ship. In this situation,itis as though the submarine were a train approachinga 7 ----=------.- REVERBERATIONS/ HIGH i4 1MHZ REVERBERTIONS,LOW 13 911Hz caratacrossing.The soundtransmission reflectedfrom the approaching submarine is I® HI) 1)11) 1)1...B111111111)11)) (1(? EM heard at a higher pitch than the reverberations. "ONE (((( (((( (((( ONE PARTICLE +UNDERWAY PARTICLE When the echo from the oncoming submarine is OUTGOING PING 14 0 mHz higher than the reverberations, report "Doppler up." When making this report, you are telling theconningofficerthatthe submarineis 71.39 heading toward your ship and making way Figure 3-25.Illustration of doppler. through thewater. This form of doppler is illustratedinfigure3-27.Noticeinthe

illustrationthatthe echo frequency of the SUB ECHO - 141 MHZ SUB ECHO- IS 9*Hz submarine on the ship's starboard quarter is the REVERBERATION- 14 REVERBERATION-13 9 MHz same as the ship's sonar frequency, yet it has up doppler. Remember, doppler is determined by comparing the tone of the target echo and the tone of the reverberations.

Doppler Down

T-1G ;NO PE IR J4GA y Just as the tone of a train's whistle decreases in pitch as the train moves away from you, so does the doppler of a submarine moving away 71.40 from your ship. No matter where the submarine Figure 3-26.No doppler. islocatedinrelationto your ship,if heis headingaw,1!fromyou, thetoneofhis returning echo will be lower in pitch than the toneofthereverberations. Fimire 3-28 gi7,ERRELo....7ON.i3 9 illustrates two situations when you would report Sufi 0 "Doppler down" to the conning officer.

DOPPLER REPORTS

REvE 49E94 TJO% -14-: To summarize what you have just learned ECB7 - 3K, about doppler: Doppler is the difference in pitch between the reverberations and the echo. When the echo is higher than the reverberations, you r 40 k will sing out "Doppler up." If it's the same as the reverberations, report "No doppler. If the echois lower thanthereverberations. s:. 71,41 "Doppler down." Figure 3-27.Doppler up. 5 9 54 Chapter3PHYSICS OF SOUND

coming directly toward the ship at2 knots. Also, a submarine coming directly toward the ship at 6 knots returns a higher echo thana 6-knot submarine that is heading only slightly toward the ship. ... The importance of prompt andaccurate ,...-, ...- reports cannot be overemphasized. Two details ...... ::.....-. ..,...... /,'/' ...... count: How much speedthesubmarineis :-...... making, pius how much it is heading t.oward / .:-...... or ...... \:-...... :, N.. away from the ship. The combination of these / twoconsiderations is spokenof as the REVERBERATION- t4.1 EVERBERATioN-13.9,Hz SUB ECHO- 14 OkHz "..."'-.'------..., SUB ECHO -13 8 loit component ot' the submarine's speed towardor DOPPLER DOWN DOPPLER DOWN away from the ship.If the submarine's speed is -4 UNDERWAY component morethan 6knots,report OUTGOING PING- "Doppler marked, up (or down)." When it is 3 to 6 knots, inclusive, report "Doppler moderate, up (or down)." If less than 3 knots. then call it 71.42 "Doppler slight,up (or down)." (Seefigure Figure 3-28.Doppler down. 3-29.)

You now realize how important itis to give When you become a really skilled operator, an accurate report of doppler to the conning you will be able to give the degree of doppler, officer. It tells whether the submarine is thatis, how high or low it coming is. For instance, a toward or going away fromyour ship, and gives submarine coming directly towardyour ship at 6 thecomponent of the submarine's motion. knots returns a higher echo thana submarine Remember that any contact that doeshave cb,ppler must be moving in the water: ifit is not a surface ship, chances are that it is a submarine or a largeish. Figure 3-30 gives an idea of the value of' doppier.

2 KNOTS KNOTS SLISHT UP \ NO DOPPLER INTERPRETING ECHOES I4 KNOTS .4 KNOTS\\\ \ SLIGH1-4UP HO DOPPLER \\NN\ 16 KNOTS "'...N* 2 KNOTS SLIGHT UP NO DOPPLER Sonar Technicians learnto recognize one echo from another by listeningto recordings of reverberations and echoes and by practicingwith the sonar aboard ship. The followingremarks \ //.. s\- may be helpful: however, they cannot substitute \\\\ Ns,13 KNOTS '''' '4'l 2 KNOTS for actual practice. m0D RATE ,....\ SLIGHT UP

4sK*.N\j ,s'S DOWN ' MODERATE DOWN ,...7, \ \ 71Ik N1,07D.;; T1/EHU/P DOPPLER/NO DOPPLER \\ \ , \;\... -*Z."- . 2 KNOTS /2,16.-; 6 KNOTS ..00,. SLIGHT DOWN 7." "Nlk:. OR ABOVE \' MARKED UP As we said previously, an echo with doppler isprobablya submarine or a largefish or mammal. A %vhale, for instance.may have echo characteristics closely resembling those ofa submarine. A strong current or tide willcause an 71.43 echo to have a doppler effect, but suchan Figure 3-29.Dopp:er conditions. occurrence is unusual.

55 GO INTRODUCTION TO SONAR from dead astern of the target is hardest for an operator to identify, it can be done with a little perserverance.

ECHOES FROM FALSE TARGETS NO DOPPLER Echoes may be heard not only from whales but from large fish, such as blackfish. Schools of herring or other small fish sometimes are large , enough to reflect a strong echo. /1414 If the water is shallow and the bottom is hard, rocky, or covered with coral heads, sound DOPPLER DOWN wavesarereflectedstrongly.Oftenthese reflections return as loud and clear as echoes from a target, but they have no doppler. Also, in shallow water as along the Continental Shelf on the eastern coast of the United States, hulls of 71.44 long-sunken ships may return a very convincing Figure 3-30.Value of doppler. echo. Because Nazi U-boats were so effective in this area during World War II the shelf is littered withdeadshipscapableofhoaxingthe If an echo has no doppler, it may be from a submarine's beam or wake, from a stopped submarine, or other large, solid surface. Such largereflecting surfaces produce sharp, clear echoes; the larger the area of the target, the greater the strength of the echo. A weak, mushy REPORT E dERYTHING echo, without doppler,isheard from such objects as riptides, kelp beds, schools of small fish,and wakes that arebreaking up. The S'JREACE VESSEL numerous small reflections combine in random fashion to form in irregular echo wave.

ECHO STRENGTH

The strength of the echo depends on the powerofthe incoming wave. This power depends on the sound output of the transducer; the size, position, and movement of the target; and the cc:lclitions of sound transmission in the sea. Often, you will receive the worst type of echoes from the stern of a submarine. The target area is small and is broicen into multiple surfaces JMPINF by the screws, the wake, and such, so that there 5UBMEP;ED is a combinationofreducedpower and interference. Don't dismiss weak, poor-sounding echoes asnonsubmarinc.Experiencedsonar 71.45 operators willtell you that, although an echo Figure 3-31.Report everything you hear.

56 Chapter 3PHYS1CS OF SOUND unsuspecting sonar operator intobelieving his Report every sound you hear, contact is actually a submarine. regardless of whether you can identify theecho. Figure 3-31 REPORT EVERYTHING YOU HEAR illustrates a few of themany objects that may return an echo or emit Oneof'the Sonar a sound. Do not delay Technician'smost making your report whileyou try to determine importanttasksistodistinguishthetarget what you have detected. By echoes from other noises that the time you decide tend to mask it's a submarine, itmay be too late. Don't be them. Sonar operators hearmany kinds of afraid to make a report that echoes.Rocks, shoals, buoys. mines, may turn out to be surface nonsubmarine. The safety ofyour ship and the craft, whales, schools of fish,wakes of surface lives of your shipmates craft and submarines.as well as the submarines are worth more than the time spent or the ordnance expendedon a false themselves, can reflect sound. contact.

6 2

57 CHAPTER 4

BATHYTHERMOGRAPH

The travel of sound waves in thesea was range prediction methods are presented in other discussed in the preceding chapter. The factors publications, such as Sonar Technician G 3 & 2, thataffectsoundtravelin water,also NAV EDTRA 10131 and Sonar Technician S 3 & mentioned earlier,arepressure, salinity, and 2, NAVEDTRA 10132. temperature. Sonar Technicians must havea thorough knowledge of these factors to interpret correctly the information displayed bysonar EFFECTS OF TEMPERATURE equipment. The speed of sound through water increases Increases in pressure speed up the velocity of at the rate of between 4 and 8 feet per second sound, making the speed of sound higher at for each 1°F rise in temperature. This 4- to 8-fps extreme depths. An increaseinsalinity also change depends on the temperature range of the increases the velocity of sound. The effects of water. At water temperatures in the 30° range, pressure and salinity are not nearly as great. for instance, a I' rise increases the rate of travel however,as theeffectsoftemperature differently than does a 1° rise in the 70°range. changesparticularly abrupt changes. Ships and submarines of theU.S. Navy Information about the ocean ternperature at operate inallsea temperaturesfrom near a given time can be used to predict what will freezing in the polar regions to the upper 80s in happentotransmittedsoundasittravels thetropics. To provide accurate range data, through the water. Because thermal conditions sonarequipment mustbeadjustedtothe of the sea are of the utmost importance to Sonar changes in sound velocity. Technicians,adevice, the bathythermograph Under some conditions. a pulse transmitted (PT),isavailableformeasuringwater by sonar equipment may travel easily through temperatureatvariousdepths.From such water that varies greatly in temperature. Under measurements, we can arrive at fairly accurate different conditions. the pulse transmittedmay conclusions regarding the maximum range at be unable to penetrate a 5° temperature change which a submarine may be detected, as wellas layer at all because itis reflected and scattered the most favorable depth for the submarine to instead. avoid detection. These two fundamentalsare importantconsiderations in antisubmarine TEMPERATURE LAYERS warfare. They influence the types ofscreens used and aid in determining the spacing of ships A pulse of acoustical power may provide in the screen. sonar reception out to several thousand yards of range. The same pulse, if transmitted into a layer Much of the data used in conjunction with of water (such as a sound channel that tends to BT information for determining sonar detection keep the pulse confined within it), may be able ranges cannot be included in this text because of to provide sonar data on contacts many miles the classified nature of the subject matter. Sonar distant.

58 6 3 Chapter 4 BAT! IYTI I I'. RMOG RAPI I

Sound has a natural tendency to seek paths counterpart. Because salini:y, temperature, and toward the cooler layers of the sea. Because the pressure affectthe ability of a submarine to temperature of the sea normally decreases with maintain desired operating depth, knowledge of depth, the path of a transmitted pulse of sound these conditions and their effecton buoyancy is is usually in a downward direction. necessary so that the divine. officer can maintain If a cross section or a profile of thesea's trim of the submarine. temperatures were taken, a nornial condition TheAN/BQII-I AandtheSSXBT mightshowa layer of waterof uniform ( su b Ina r i ne expendablebat hyt h ermogra ph) temperature (less than 1/20 temperature change) provide the necessary data. fromthesurfacetovaryingdepths.This condition is called isothermal. Next, there would DEPTH-SOUND SPEED be a region of' water in which thetemperature MEASURING SET AN/BQH-1A decreased rapidly with depth. Suchan area is knownas a thermocline. Finally,forthe TheAN/BQII-1 A is a remainderofthe completely measureddepth,the transistorited device used to provideaccurate temperature would decrease only slightly with information depth. concerningsoundranging conditions in t hesu rrou nd i ig wa terand buoyancy during diving operations. Thermoclines The equipmentiscapable of measuring sound velocity in seawater overa range of' 4600 The thermocline can play havoc witha pulse to 5100 fps.Accurate depth measurement is of acoustical energy. As the transmittedsound provided by a depth element and its associated pulsereachesthethermocline, one of two effects is apparent. circuitry. Velocity of sound and depth ofthe sensing element which measures this velocityare First, the thermoclinecan prevent passage of displayed on a two-channel (pen and drum) thepulse,reflectineitback to the surface. servomechanism recorder (fig. 4-1). Targetsbeneaththethermoclinemaybe Maintaining the trim of a moving submarine undetected. This possibility isone of the reasons is aided greatly by indicatingon the recorder submarine commanding officers seek the cover chart a series of isoballast lines. These linesare of such thermoclines, hopingto evade detection precalculated for various classes of submarines. by surface ships or aircraft. Charts must he selected with isohallastlines Second, the thermoclinecan allow passage of printed for that particular class of' submarine.In thesoundpulsebutalteritsdirection indicating a trace that crosses the isohallast lines, considerably in so doing. This effect is called action of the pen and drum gives theamount of refraction. If a sound pulse entersa thermocline waterto pump orfloodtomaintainthe at,for instance, a 300 angle from the sea's submarine's trim. surface, it is possible for the alleleto be altered Buoyancy changes, indicated by crossings of to 700 or more while traveling throughthe isoballastlines, may be related to submarine thermocline, and change againas it emerges. The depth and also to velocity of sound in result of this refraction can be water. a distorted path Both submarine buoyancy (uponwhich trim of sound travel that affects theaccuracy of depends) and velocity of sound in target presentation at the sonar console. water are definite functions of salinity,temperature, and pressure.Inasmuchasamoving submarine encounterschangineconditionsofsalinity, SUBMARINE temperature,andpressure,the AN/BQH-1A BATHYTHERMOGRAPH SYSTEMS recordingequipmentmustmeasurethese changes in terms of' absolute values of velocity Moreinformation is requiredfrom a ofsound in water. Sensitivityofthe submarine BTthanfromits surfaceship velocity-measuring portion of this equipmentis

59 6 4 INTRODUCTION TO SONAR

4.1

0-.800 FEET

1-1J 1:4 PRESS TO SET 4800 F10'SEC

RECOROER ILLUIA ON

SPARE

35.156 Figure 4-1.Depth-sound speed measuring set AN/BQH-1A. sufficient to indicate changes in sound velocity Funct io nal Operation of 1 fpswhenpassingthroughathermal gradient.Equipmentpressurecircuitsare To measure sound velocity and to ascertain capableof'indicatingchangesindepthof velocity gradients in the surrounding water, two approximately 1 foot.Thismeasurement t ra nsdu cerassemblies(sound heads)are represents the minimum readable definition of provide cl w i t 11 eachdepth-soundspeed the recorder chart's pressure portion. measuring equipment. One assembly is mounted on the upper (or sail) portion of' a ship. The Isoballast curves are calculated in such a way other device is mounted at the keel. that individual curves pass throueh all points To obtain accurate information concerning where a loss in buoyancy with depth exactly changing gradients and subsequent effects on equals any eain in buoyancy resulting from a buoyancyduringdivingoperations, it is decrease in water temperature or increase of advisable to use the lower sound head while salinity. 6 5 diving,andtheuppersoundheadwhile

60 Chapter4 BATHYTHER MOG RAPH

ascending. By following this pattern, radiated REPEATE R. Therepeater unit is identical heat from the skin of the ship will wash away to the recorder unit, but the repeater has no from t he sound head. Radiated heat, operational controls. The only control on the consequently,willnot interferewith repeater is the power on/off illumination switch. measurements of gradients and indicatioir of The repeater cannot be operated unless the corresponding buoyancy changes. recorder is also operating. Sound velocity in water is measured in the following manner: The AN/BQI-I-1A transmits Operating Procedures into the water a pulse or acoustic energy. This tieciu.:- the AN/BQH-I A and its associated pulsetravels from a transmitting transducer sound heads through the water and is received bya second circuitry are completely receiving transducer. The time required fora transistorized, no warmup time is required for pulse to travel from transmitter to receiver is properoperation.Followingisthenormal measured by means of electronic timing circuits. operating procedure recommended for the set. Thus, a direct measurement of sound velocity is I. made.This method ofdirectmeasurement Afterlighting off the equipment and ciiminatesthe needforcorrelatingvarious selecting the desired sound head, the recorder factors of the ocean: salt content, density, and illuminationcontrolisadjustedtoprr vide temperature.pluspressurecorresponding to sufficient light to clearly view the chart. (NOTE: depth at which velocity is measured. When surfaced.the upper sound headis not immersed.Care nrist bc takentoavoid Description of Controls energizingthis hcad untilthesubmarine completely submerge,' 1 OperatingcontrolsoftheAN/BQH-I A 2.The depth scale select switch is set to the depth-sound speed measuring set are described desired depth setting (0-800 feet or 700-1500 for the recorder and repeater. (Refer to fig. 4-1.) feet). The equipment is now ready for normal operation. 3.Thepress-to-sct RECORDER. Following are themajor 4800fpsswitchis operating control switches on the recorder. depressed and held until the velocity indicating 'rumreaches a steadyposition.Indicated I.Power onloffrecorder illumination elocity position should be 4800 Ups. (NOTE: control: This controi applies 400-hertz primary Cor each sound head the absolute value of the power to the re.:ordcr. Ii varies the brightness of 4800-foot calibrate velocity varies slightly. Test the internal chart'omination. data sheets supplied for the sound head in use shoulr' be consulted forexactcalibrated 2.Sound lie. d scH A two-position readings.) switch that perhnt 1 ,,..rator to select either 4.In the preceding step, when the drum the upper or Ii mild head for displaying steadies, the press-to-set switch is released. The sound velocity on the recorder drum. drum should rotate and indicatethe sound 3.Depth scaleselect: Atwo-position velocity in the water at the sound head in use. 5. switch that permits an operator to select either When both sound heads are immersed. of two overlapping depth scales. One depth scale the sound head select switch may he rotated to is 0 to 800 feet: the other. 700 to 1500 feet. selectfirstone,thenthe other, sound head. Each time the select switch is changed. the drum 4. Press-to-set 4800 fps: A spring-loaded shouldrotatetoa positionthat shows the switcU, that, when depressed. applies a velocity of sound at the sound head selected. calibratingsignalinternally generatedinthe When shifting from one head to the other. the particular sound head in use. The switch acts as recorder also indicates the difference in depth a system check of performance and accuracy of between the two sound heads. soundvelocityindication.Italsoassistsin 6. Thepress-to-set4800fpsswitch is proper positioning of new recorder charts. depressed. When the drum rotates to a velocity

61 6 6 INTRODUCTION TO SONAR

reading or 4800 fps, the switch is released. The When the float assembly reaches the surface, drum thenwillrotate and beginto give a atmospheric pressure actuates a pressure release continuous record of velocity and depth for the mechanism and the probe is released for its trip sound head in use. to the bottom, trailing the fine wire behind it. The wire relays back to the submarine the Checks and Adjustments temperature information until the probe reaches the bottom or 2500 feet. At this time, the entire Minimum front panel controls and adjusting unit is deta -hed from the ship and sinks to the knobsarecontainedonthe AN/BQH.IA. bo ttom. Periodically, the operator should depress the press-to-set switch and verify that the initial calibrationaccuracyoftheequipment is SURFACE SHIP EXPENDABLE maintained throughout an operating period. BATHYTHERMOGRAPH SYSTEM Emergency Use Thesurfaceshipexpendable bathythermograph system (fig. 4-2) has a sensor Becausethevelocitydisplayand depth probe, a cannister, a launch mechanism, anda display on the AN/BQH-1A are independent of temperature-depthrecorder.The expendable each other, the recorder is capable ofemergency portionofthesystem,consistingofthe operation on either independent channel.If cannister and the probe, is seen in figure 4-3 and failure of the depth circuitry occurs,an operator figure 4-4. The probe weighs about 1 pound and maycontinuetosupplyusefulvelocity information by manually positioning the depth pen to a readable portion of the chart. In the event of failure in the sound heads or drum Canister Loading Brooch circuitry,depthinformationmaystillbe supplied independently. Canister Wire Spool

SUBMARINE EXPENDABLE Launcher Recorder Cable (4-wire LAUNCHER BATHYTHERMOGRAPH (SSXBT) shielded) Stanchion TheSSXBTautomaticallyobtainsand records ocean temperature data without the Optional Alternating- Equipment', Current Power necessity of changing the submarine's depth. Cable (3-wire) The SSXBT is launched from the left signal ejector of a submarine and provides a complete temperature profile from the surface of the I Dopth/Tomporaturo ocean down to2500feet.Allofthisis Terminal Chart accomplished in less than four minutes. Board 11. j The submarine bathythermograph consists ti

of a ballistically-shaped BT probe contained ina RECORDER float assembly. The float assembly also contains a lifting body. When the assembly is launched fromthesignalejector,theliftingbody separatesfromthefloatassemblyandis attached to the submarine by an insulated steel cable and a signal cable. The lifting body floats in suspension behind the submarine andpays out a fine two-conducter cable as required. The float assembly rises to the surface dereeling the 71.126 same fine cable as required by the ascent rate. Figure 4-2.Expendable BT system.

62 6 7 Chaptcr 4 BATIIYTIIIKRMOGRAPII

71.118 Figure 4-3.Expendable BT probe in its cannister.

.02$711P 414r.

*a.

0'4

71.127 Figure 4-4.Expendable components and launcher.

63

6 8 INTRODUCTION TO SONAR

is spin stabilized. It contains a thermistor, which water. (The cannister remins in the launcher.) senses temperature changes, and a reel of speci-al Astheprobestartsitsfreefall,thewire wire. The cannister also contains a reel of wire, commences unreeling from the probe and from and holds the probe. The launcher is essentially a thecannister.This doubleunreeling action tube for holdinv, the cannister. It can be installed allowsthe probe to sink straight down and toproVide through-the-hull launching of the permits the ship to proceed unhindered. probe,eliminatingthenecessityforsonar personnel to be on deck in rough weather. The Whentheprobestrikesthewater,an recorder (fig. 4-5) plots a track on a strip chart electrode triggers the recorder. The thermistor of temperature versus depth in real time. The transmits temperature changes to the recorder strip chart is synchronized to the probe's rate of where they are plotted on the strip chart by a descent. stylus. At a depth of 1500 feet, :he probe's wire is exhausted and the recorder stops. A complete OPERATION readout is obtained in 90 seconds from time of launch. Temperature range of the probe is 28°F 10 96°F, with an accuracy of 0.4°F. Depth When you place the cannister in the launch accuracy is2 percent or 15 feet, whichever is tube,awaterththtelectricalconnection is greater. formed between the probe and the recorder, causing the recorder to run for 2 seconds. This Figure4-6shows a representative action sets the automatic starting circuits, which temperature-depthprofile. Only 6 inchesof' are activated when the probe hits the water. The chart paper are needed for each 1500-foot drop. probe is held in position by a pin protruding from the launcher. Pulling the pin permits the probe tc"allfree of the cannister, into the READING XBT RECORDER TRACES The XBT, as already pointed out, provides a continuous visual record of the temperatures from the surface o: the sea to a depth of either 1 500 feet, 2500 feet, or a point at which the wire breaks. The temperatures of various ocean depths recorded on the chart are represented as a graph of temperature against depth.

Fr 0111 thetemperaturecurve,onecan discover the sound pattern of the sea at the time of the hathythermoosaph observation. It is from the sound pattern that an estimate of maximum sonar range can be made.

'Fle variation of temperature with depth can complica ted. Many different conditions h:. represented by the different types of trace,;.

Itisconvenientto consider the water as layers. In each layer the tempefature can change from top to bottom. Create a mental picture of 71.119 the location or these layers from the appearance F. lure 4-5.BT recorder. ofthechart. Visualize,too,howthe

64 6 9 Chapter 4BATHYTHERMOGRAPH

71.120 Figure 4-6.Recorder chart.

temperatureis changing. Study the followine gradientsspelltroubleforsonaroperators examplesuntileachkindoflayercanhe because they result in short identified easily. sonar ranges. POSITIVE GRADIENT NEGATIVE GRADIENT Sometimes. layers are found in whichthe A negative gradient condition existswhen temperature increases the temperature of the water deereases withdepth. The trace with slopes to the right. Althouuh usuallyobserved in depth. An \ HT, lowered throughanegative coastalwaters,this condition may be found gradient, produces a graph with the tracesloping anywhere. In figure 4-S a positive gradient totheleftas is depthincreases.Figure 4-7 shown to exist down toa certain depth. beyond represents a ;lace showing a negative gradient. aegative is firmed. Depending Thisillustratioiidepictsa particularly sharp or nepth of the start (1(.1)1 of thenegative gradient.whichis quite common. Negative g:.1-.ent. such a trace also me,,n trouble for INTRODUCTION TO SONAR

theSonar Technician.Asaresultofthis the top of the negative gradient are difficult condition, the shipboard sonar operator observes targets to detect.TheshipboardSonar unusually long ranges to targets near the surface. Technician may get extremely long ranges on a Littleofthepulse'spowerpenetratesthe submerged tari4et near the surface (such as the negative gradient, however. The reason is that underwater sectionof thehullof another the higher temperatures in the lower part of the screening ship), but he may be Linable to detect positive gradient bend the pulse back up toward a submarine just a few thousand yards away. the surface of the sea from which itis reflected Shouldthesubmarineenterthepositive downward again, and so on, forming a surface gradient,however,it probablywouldbe channel. detected. Any enere.yof the pulse that,.!oespass through the negative gradient is reduced u,reatly, ISOTHERMAL LAYER and the sound beam is bent sharply downward. An isothermallayer of wateris one of Submarines operating 50 feet or more beneath fo rmornearlyuniform tempera ture

769;

t_.

177-9 (5"

-ICRUISE j.4 Q .

LONG-_ V:. 7 . 17: 7 !'" . 14.02 -0'.?.S=C. NO

7 1 71.128 Figure 4-7.--Negative gradient.

66 Chapter 4BATHYTHERMOGRAPH

throughout. Thisconditionis not confined remperature profile of the sea. Notice thatevery necessarily near the surface of thesea, but often time a straight, vertical BT is found between layers trace is recorded, the or gradients of markedly layer of water between its limits is knownto be different temperatures. An isothermal condition isothermal. canbecaused by waters of two diffen.nt t emperaturesmixing. Inthisrespect, it sometimesisreferredtoasa mixed layer. DAILY HEATING Isothermal layers are of importance inpredicting the path the sound pulse will follow.For this Daily heating of the surface waterlayer has a reason Sonar Technicians must be able to read marked effect on sonarranges.It produces a accurately the top and bottom depths ofsuch a condition ASW men call afternoon effect. layer. You are shown an isothermal condition in When the surface is heated bythe summer figure 4-9. Now look at figure 4-10to see how sun, and the winds are not strong enough isothermal layers sometimes to are located in a keep the surface water well mixed,the water

7 2

71.129 Figure 4-8.Positive gradient.

67 INTRODUCTION TO SONAR

71.130 Figure 4-9.Isothermal layer.

'1E

71.89 71.90 Figure 4-10.Temperature profiles. Figure 4-11.Effect of daily heating. ri 68 NOAAOCEANAv Fowl 3167/H6-72) 77 -22 II -72) FOR NAVY SHIP IPA TYPESHIP NUMBER HULL YR MON BATH YTHERMOGRAPHand The NATIONAL OCEANIC AND ATMOSPHERIC LOG ADMINISTRATION inPrepared accordance by the with OCEANOGRAPHER specifications istablithed OF THE by NAVYthe SOON TYPE NMBRSOONFOR NAVY AIRCRAFT USE NUMBERSORTIE YR' MON I I. REFERENCE TYPE IN ARAI PL A FORM DESIGNATOR INTERGOVERNMENTAL OCEANOGRAPHICend WORD COMMISSION METEOROLOGICAL 11015 ORGANIZATION IWMOI . -t I LU r CR0151 NUMBERINFORMATION PR011COUNTRY C I INSTITUTION III. RADIO MESSAGE INFORMATICN 6 S T A TtON NUMBL A OBSERVA TION NUMB!, INS T RUMEN I ME SSAGE PREFIX rDA II 'GI,.MON 113TA TIT nOuI ART .Gml. AnTI OT2ITUDE INO3TA .712 1 II. OPTIONAL ENVIRONMENTAL INFORMATION WINO - SEA LEVEL 3 AIR TEMP 5 kt, VIX X I I I 5I, I (MT I PE,1 1451 I IilITT I 0 I UM DIII a SPEED r PPESSURI 9,, DRY BuL1211 1 1 Sn AIR TEM, WE T BULBI I I DT INT II DEPTH DIN IMIPTPTFINAJGRAT, TRACT RI AL N05 If m _L. I-8181810iTAM, 5l ., TI MI, 6 WAY I. 1 Pppi, 5 yr LL N T 6 SOu A. 9 10 I I OM PER, 0 ACTIA I KIN PRET. 02 T BANS olo ,-,:i,, ..,, L ANC. sTIN i I R ti "" 1 1 1111111111 I P 1. TR 2.5 MBE P I. REFERENCE1151910 INFORMATION A TN,. NuS1311 It INS T.'S.T.TT N I P.11.5S,.1 OAT DAIT DAlI A(11Yel 7 v I I II. OPTIONAL ENVIRONMENTAL INFORMATION J , X , X 5., i um .151 1 ... ' I 1. POI S5,21 DRY If, 1. T ,I I 7ti-L I, T 1 T 2IT i '' '' t Sn I.T1 TIT. 13.432 5 ODD SWELL -- - 2, -- T I.2 R Err m T TUALTIA0 2T2N PREL TITANS-- I i T- I. REFERE:' I-i---- rm T 9111,1,11 52".22II II 22 BSI BEA 71.1.. 111511. 14.1.11 NI 3'01 INT.p5.201.22. uT 0 T.. 1 II. OPTIONAL ENVIRONMEN'AL INFORMATION Da+ sno No SPIT_ IT 2 PRESSURESIT., LEL., A IT TEMP X GPO. 0 2T.Ifflu 1 T 2 1451 I uM - P 1 I. VTOLA2.I I 0 LB o/IH. 1100 Di PIN DVN 1-.1 : I (A (NI DTP 10els 8181s TIM/ 5T A, TEMP - C 6 WA., E 2-0 PAO A IONSOL A l PACCA P4071 o I o qv, 1 I , P... "... ZSTflWW.IImo= RI..., P,.., impN... LAN . P PI R I R5 fT 1 1 DAD. 12 ALL REMARKS II. 11111 Figure 4-12.--BT log sheet. h±i I hr 71.92 INTRODUCTION TO SONAR closeto the surface may be several degrees Record N or S and E or W after latitude warmer than the water 20 to 30 feet down. This and effect is maximum in the late longitude, respectively. Record timeand date afternoon, and according to GMT. DO NOT OBSCURETHE usually disappears at nightas the surface cools TEMPERATURE TRACE. off and water continues to mix. Figure4-11 is a simplified illustration showing howtraces may Ship indicatedailyheatingorcoolingnearthe Cruise surface. Latitude An isothermal layer isseen at 0600 (local Longitude time) on a calm, clear (lay. From0600 to 1600 Time (GMT) the surface is shown gaining heat fromthe sun Da/Mo/Yr faster than it can dissipate the heat backinto the Observation # atmosphere. The surface temperature Bottom Depth* increases, *optional entry. and a negative gradient layer, representedby the crossed lines, is established. This layerdeepens as the heat penetrates, and diffuses downward by conduction during the time thesurfaceis BATHYTHERMOGRAPH LOGS gaining heat. The BT Log, OCEANAV 3167/1(6-72), After1600thesurfacecoolsoffby figure 4-12, is designed to meettwo basic needs: evaporation faster than it receives heatfrom the (1)providea messageformatforradio declining sun. The cooler and densersurface transmissionofsynopticBT datafor water mixes and may destroythenegative oceanouaphic forecasting, and (2) providethe gradientlayer.Sufficientcooling may occur National Oceanographic Data Center(NODC) duringthenighttoreestablish a single with information required for BTanalog and isothermal layer, as shown at 0400. digital processing. This radiomessage format supersedes all other formats previouslyused for (BT TRACE MARKING shipboard or aircraft BTmessage reporting. The graph of each XBT drop The instructions provided with thelog sheet must be describe (1) how and where mnotated to have any meaning. Thereadings to mail log sheets )btained from a drop andrecordercharts;(2)howtoobtain are not used only on your additional log sheets; (3) how hip; the information is also usedto make up to address radio ange messages; (4) how to mark the XBTrecorder predictionvehiclessuchas SHARPS chart after the observation Ship/HelicopterAcousticRange istaken; (5) the Prediction procedures forfilling ;ystern). If the time, date, location,etc., were inthe "REFERENCE ot known, the information would be uselessfor INFORMATION," "OPTIONAL ,ost d'op purposes. ENVIRONMENTAL INFORMATION,"and "RADIO MESSAGE INFORMATION"portions iow to Mark the of the log sheet; (6) the requiredinterpretation .B.T Recorder Chart of the temperature-depth trace,and (7) special instructions for Navy use. The m,trking of the XBT recorderchart has These instructions alsoserve to amplify the 2en standardized, and the proper method is following directives, the latest editionsof which (plained below. are applicable and should be rigidly followed:

Enter on the face of each XBTrecorder 1. OCEANAVINST 3160.9 iart the information listed below in thesame 2. COMSCINST P3121.3 quence. If the format for this information is 3. COMSCINST P3120.2 )t preprinted on the XBT recorder chart, write .._4. COMDT USCG INST 3161.1 in. 5. NAVWEASERVCOMINST 3140.1. 70 CHAPTER 5

BEARINGS AND MOTION

In studying bearings and motion, you must distance from the sound transmitting ship. In remember that they are of two types. The two chapter 3 you read about the numerrsiis variables types of bearings are true bearing, which uses affecting the travel of sound bea in water. true north as a reference, and relative bearing, These variables greatly affect the precision with which usesship's head as areference. True which the exact location of an underwater target motion is the movement of an object across the can be determined. With present-day equipment Earth. Relative motion is the movement of one we are able to compensate for many of the object in relation to another object. variablesandobtainexactpositioning This chapter discusses both types of' bearings information. Electromechanical computers are and both types of motion. It shows how they utilizedin solving many of the problems of areappliedindetermining the location and target bearing and motion. It must be borne in movement of an underwater target, such as a mind, however, that direction and distance must submarine. be obtained first. then reported by the operator With modern sonar, it is possible to locate More the :oinputer can be set up to produce a andtrack a submarinewithdependable correct solution. Thus, the ability to determine accuracy.Tomakefulluseofprecision and rep)rtthe correct bearing and range as equipment, itis necessary to evaluate bearings speedily as possible is ot' the utmost importance and motion correctly and thus avoid setting to the entire attack problem. erroneous values into the equipment computers. SONAR INFORMATION REQUIREMENTS FOR LOCATING SUBMARINES Sonarprovidesthetwoitemsof information --direction anddistancefrom Many landmarks and familiar objects on land which we derive all subsequent data. Direction can be utilized for establishing a position and and distance are referred to as bearing and range. determining the location of a particular point. In Correct interpretation and transmittal of bearing civilianlifewewereaccustomedtosuch and range information are deciding factors in descriptive terms as "The third house on the successfully conducting any attack. right," or "Just a mile down the highway at the big signboard." At sea, though, we must adjust Bearing ourselves to doing without the convenience of familiar objects and use other means at our The direction of the echo from the sound disposal for locating a target. Targets visible on transmission source is called the bearing. Bearing the surface or in the air can be pointed out, but is measured clockwise in degrees ot' azimuth in an unseen underwater object must be located in three figures from 0000 through 3600. Azimuth a manner that is both clear and accurate. This is defined as a horizontal arc of measurement of method of location is accomplished by using the horizon in degrees. One quarter of a circle is sonar to determine the objecrs direction and 0900 and a full circle is 360°.

71 INTRODUCTION TO SONAR

Until a few years ago, an allowance of 2-1/2° for error in bearing was considered withinlimits of tolerance in antisubmarine attacks.Today, this standard of tolerance has been reducedto approximately 1°. A bearingerror of 2-1/2° at 100 yards amounts to a positionerror of 4.36 yards; at 2000 yards thiserror is 87.2 yards. With a bearing error of 1°, we are off target only 1.75 yards at 100 yards, and 35yards off at 2000 yards. As you can see, modern equipment has provided geater bearing accuracy. No doubt SONAR CONIAC1, BEARING ,30' future sonars will give even betteraccuracy, but remember that the finest equipment willalways need a competent operator.

Range

The distance from the soundsource to the target is called range. In sonar,range alv vs is expressed in yards. Withmodernsonar equipment, range detection varies fromless than SONAR CONTAcT bEARINC 045 100 yards to thousands of yards. Rangescan be measured to an accuracy of 1% ofthe range scale in use. To achieve thisaccuracy, you must have up-to-date knowledge of water conditions andbeableto make adjustmentstothe equipment to compensate for variationsin the velocity of sound. Range is reported in thousands and hundreds of yards. Some sample ranges and the manner in SONAh CCN7AC REARTNO 2 which they are reported are listed here foryour C information. 71.3 3000-"Range three thousand, closing." Figure 5-1.True bearings are independent of 2500-"Range two five hundred." ship's head. 1750-"Range one seven five zero." 1100-"Range one one hundred." 1000 -"Range one thousand." constant is of vital significance. A successionof 800-"Range eight hundred." both bearing and range reports isrequired to "Kringe six six zero." determine target and location and motion. -"RE. -ige one five zero." i.)0-"Range four hundred, opening." BEARINGS It should be noted that the word "yards"is lever included in a report because ranges always In establishing a bearing,we invariably must ire given in yards. haveareferencepointto ensurethatthe directionisalways the same. True bearing is One range report by itself is insufficient to referencedtotruenorthregardlessofthe .onduct an attack although such informationas direction or motion of the ship. Relative bearing vhether therangeisopening,closing,or is always referenced to the ship'sbow. In all 72 7 7 Chapter 5BEARINGS AND MOTION instances, bearings are reported in degrees and contacthave been drawninto showthat, are read clockwise. although the ship has a different course, the true Sonar bearings are reported in three figures, bearing of the contact remains the same. In the and you say "zero" instead of "oh.'' A sonar illustration, compare the examples on the left contact due east of your shipis reported as with the examples on the right. a.ir contact, bearing zero niner zero." If the Allshipboardandsubmarine sonar sets coniaet were due west, it would be reported as utilizea gyrocompass input to provide true "Sonar contact. bearing two seven zero." targetbearing by reading the sonar bearing Notice inthe foregoing examples that the marker against the dial. Figure 5-2 shows this word"true" is notused.Unlessstated dial asitis in a standard shipboard sonar set. otherwise,always assumethatbearingsare The section enclosed within the dotted lines is reportedastruebearings.Ifagyro failure the area visibleto the sonar operator through occurs, relative bearings must be used, and the the glass window. The marker at the top, which sonar operator will add the word "relative" to can be seen through the transparent bearing dial, his bearing report. II he wishes, the operator can indicates the bearing to which the operator has avoid saying"relative" after each report by trained the cursor on the scope. Because the stating "All bearings will be relative until further cursor normally is positioned in the middle of notice." the target presentation, the dial marker indicates the center bearing of the contact. TRUE BEARINGS RELATIVE BEARINGS Toillustratethattruebearingsare indypendent of the ship's heading. figure 5-1 Truebearings arethe ones of principal shows three different bearings. The ship and the concern to Sonar Technicians because standard

45.29A Figure 5-2.Bearing dial assembly.

73 7 8 INTRODUCTION TO SONAR

operating procedures are based on true bearings. more stability,the operator can control the You needtounderstandrelativebearings, equipment so that a relative picture is presented however,inasmuch ascasualtiestothe on the scope, the dial indicating relative bearing. gyrocompassnecessitateshiftingtorelative Figure 5-5 typifies a bearing indicator from bearing procedures. which true and relative bearingsmay be read Relativebearingsarereadindegrees simultaneously. This type of indicator, used in clockwise from the ship's bow, which is always earlier sonars, is a good example for showing the 0000. If a contact is broadon your ship's port comparr,on of true and relative bearings. quarter, the relative bearing is 225°. If a contact The outer dial, whichisfixed, indicates is on your starboard beam, the relative bearing is relative bearing. The inner dial is free torotate. 090°. Figure 5-3 diagrams thesetwo examples, When connected electrically to the ship'smaster illustrating how relative bearingsare determined. gyrocompass,itacts as a gyro repeater and When the ship changes course, the relative shows ship'scourse andtruebearing. The bearing of a target changes. In figure 5-4 the ship diamond-shaped poiniel between the two dials indicatesthedirection changes course 60° to the right. Thiscourse in which the sound change causes the relative bearing of the target receiver is trained. Both relative bearing andtrue to change from 090° relative to 0300 relative. bearing are read by observing the position of the pointer. Relative bearings can be read on thesonar True courseisread ontheinnerdial console from the same dialthat 6ves true opposite 0000 relative on the outer dial.As bearings, although not at the same time. Ifa shown in figure 5-5, ship's course is 045°, anda complete gyro failure should oceur, this dial contact broad on the starboard bow (045°R) has automaticallyindicatesrelativebearing. a true bearing of 090°. Occasionally, the gyro may act erratically fora few moments, causing the pictureon the scope STERN LINE INDICATOR to jump, making it difficult for the operatorto track the target. To obtain a presentation with With modern scanningsonars the sonar operator has an ideal picture of antisubmarine

0 YOUR SHIP DE4O ALWOYL IS 900' A RELATIVE. 000.' PORT 5T'EfD BOW, BOW LL BEARINGS 0 . MEASURED 7/3, ( CLOCfMSE 7ROM THE BOW

,,ROAD UN . 0300 RELATIVE PORT. 2 BEAM

POR T QUARTER "JUAR 7.5P 180' 0900 RELATIVE A S`ER N

45.298 45.29C Figure 5-3.Relative bearings. 7 9 Figure 5-4.Relative bearing change. 74 Chapter 5BEARINGS AND MOTION

BEARING TARGET CURSOR ECHO

3500 ®10

""t....70 t 80 a SO

100 o 110

.4ea? V- obs 001. 4,-- z Att 1/464oz1111111113*15\44\w e.130 \ 40 Iplt11111\,\O"' 150 ao 10 160

STERN EXPANDING NOISE 45.29K CURSOR CIRCULAR INDICATIONS Figure 5-5.Bearing and course indicator. SWEEP

45.29J action. He not only receives the audioresponse Figure 5-6.Stern line indicator. but is aided by a video presentation 3600 in azimuth. The presentation is a true picture of the areasurroundingtheship,and (with the presentation on the scope. Only thestern exceptions ioted later in the text) it does not line indicator shows when the ship is turningor change with alterations in ship'scourse. if a course change has occurred. When turning Althought hevideopresentation is right,thesternline moves clockwise; when independentofship'sheading,theSonar t u rn i ng left,itmovescounterclockwise. Technician needs to be constantlyaware of the Movement of the stern line alerts the operatorto ship's course for purposes of conducting search course changes so that he then can be prepared arcs, performing controlmanipulations, and to make adjustments to keep the bearingcursor reportingsonarinformation.Ship'scourse on target. information is provided in the form ofa stern When looking at the scopeitisbest to line on the face of the scope. The stern line, picture the ship asin the center of a small illustratedinfigure5-6,ispresented as an segment of the ocean, with theocean always illuminated brokenline, which, asits name oriented to true north at the top of thescope. implies, indicates the direction of the ship's The ship turns in the center, and its directionis stern. If this line indicated the bow of the ship, shownbythesternlinetoindicatethe itwould be much easier to interpret ship's reciprocal of the true course. course. Because most sonar information comes from forward, however, the addition of thestern line indicator in that direction would tend to GYRO FAILURE clutter the scope unnecessarily. Normally, with the ship's gyro operating, When the gyro is operating, the top of the own ship's movement does not appreciably alter scopeisnorth(000°T). When the gyrois

75 n INTRODUCTION TO SONAR

000

270 BEARING CURSOR

TRUE PICTURE 180 RELATIVE PICTURE

71.4 Figure 5-7.Effect of gyro failure. noperative, the top of thescope is 0000 relative With a gyro casualty, thestern linewill 'ship's head). swing 90° counterclockwise. The first indication of The entire video a gyro casualty is the presentation will changea like amount in the Tratic movement of thesternlineor the same direction Ilurnination of the red GYRO OFF as shown inpart B of the light on the illustration. To remainon target, the bearing onar console. Any failure of gyro inputto the cursor onar causes the stern line to swing mustalsobetrained90° to 180° counterclockwise. The dials below elative, where it remainsas long as the gyro the scopes in iputs are cut off. If the ship is the illustration indicate thedirection in which headed for a the bearing cursor is trainedto maintain contact. arget when the gyro fails, the targetecho moves ) 0000 relative. Thus, the shipmay be heading CONVERTING TRUE )1- a target bearing 090° true, but thetarget AND RELATIVE BEARING7 :ho is presented at the tOp of the scope. Even though you logyro input to the The effect of gyro failure isillustrated in sonar, you can easily determine the gure 5-7: Part A shows the scope with true bearing normal of the target if you knowyour ship's course and tro input. The submarine is located to theright the relative bearing of the 7 center. The stern line isat 2700 and indicates target. If the relative bearing is 029° and thes Lat the ship is on course 090°true and headed p's course is 027° ,r the contact. true, as in figure 5-8,you can see that true 8 bearing of the target is 056°. Thetrue bearing is 76 Chapter 5BEARINGS AND MOTION obtained by adding the ship's course and the target's relative bearing. Thus, by the formula we have:

027°T + 029°R = 056°T 071° Now examine figure 5-9. The ship ison a course of 180° true, and the target is at 251.° relative. Again, it is easy to determine true target 41) bearing by applying the formula as before: TARGET 251° 180°T + 251°R = 431°T /RELATIVE This time the bearing is greater than 360°. When the answer exceeds, 360°, you must subtract 180° this figure to obtain the correct answer. Thus:

I80°T + 251°R = 431°T 360°T = 071°T

4 Rules for Conversion SHIP'S HEAD Certain rules are established for converting true and relativebearings. After each rule is 45.29G.2 stated, the mathematical formula representing Figure 5-9.Target at 071 ° true.

the rule is given. The formulas are expressed in 4 firecontrolsymbols.Bymeans ofthese SHIP'S HEAD symbols, we avoid detailed explanations of the values or measurements. Followingare the fire control symbols used in these formulas. ByTrue target bearing BRelative target bearing 029° RELATIVE CoOwn ship's course 'TARGET True targetbearing equals relativetarget 056° bearing plus own ship's course. In formula, this rule is expressed thus: By = B + Co If the true bearing, as computed, is greater than 360°, that value must be subtracted from the total. Our rule now is: True target bearing equals relativetarget bearing plus own ship's course minus 360°. By = B + Co 360° 45.29F.2 If you know your course and the true target Figure 5-8.Target at 056° true. bearing, the formula may be worked inreverse

77 9 INTRODUCTION TO SONAR

to obtain the relative target bearing.Relative movement. As an example, assume target bearing equals true target bearing niinus your ship is own ship's course. on a course of 000° .at a speed of 20 knots. You are overtaking and will pass close aboarda ship that is also on course 0000 but whosespeed is B = By Co only10 knots. As you close the ship,the bearings to him draw aft Eventuallyyou pass If the true bearing is less than the ship'scourse, him and he falls further and furtherbehind. His 360° must be added to thetrue bearing before relative movement fromyou is approximately subtracting ship's course. Relative target bearing 180°, but his true movement is 000c. equals true target bearing plus 3600 minusown Followingarethreerulespertaining to ship's course. relative r lotion that you must rememberwhen making an attack on a submarine. Figure5-10 B T. By 4- 360° Co illustrates these relative motion situations. If the true target bearing is 045°true and 1.If range is closing and the bearingsare ship's course is 270° true, for example,we find drawing toward the bow,your ship will pass the target's relative bearing thus: astern of the submarine. 2.Ifrangeisclosingandthebearing remains steady, the ship willpass directly over 045°T + 360° = 4050 270° = l35R tilt: submarine. (If the submarinewere on the surface, a collision would result.) 3.If range is closing and the bearingsare MOTION drawing aft, the ship willpass ahead of the submarine. As mentionedatthebeginning of this chapter, the two types of motionare true and ADVANCE AND TRANSFER relative. The Sonar Technicianmust have a thorough understanding of both types ofmotion When a ship changes to interpret target movement correc'!v and course to lied for a to new hca,ing, she does not me ve as a car does Ove assistance in makingan attack. on land. Water is a fluid substance, and itdoes not allow tlie ship the advantage of go(1traction. TRUE MOTION As rudder is applied to a ship,a short ensues before the rudder takes hold in the water. True motion is the movement ofan object During the turn, the stern of the shipactually across the Earth, using true (geographic) north slides through the water. As it slides,the ship as the reference point. tends to advance in thesame direction of her original course. The distance the Jiipmoves in RELATIVE MOTION the original direction until she ison the new course is called advance. The amount of a6vance Relative motion is the apparenttr7wement depends on ship's speed, amount ofturn, and of an object in relation to another obje,:t.Do amount of rudder angle applied. not confuse the concept of relative motion with During the change in course, the ship also relative bearing. Relative motion ismeasured as moves at right anglos to the originalcourse. The apparent movement with respect toown ship. distance the ship moves at right anglesto the original course during the turn is calledtransfer. You may have been unaware at the time, but The amount of transfer,aswithadvance, on many occasions you have witnessed the depends on the amount of turn, ship'sspeed, solution of relative movement problems. Whena and amount of rudder angle. baseball player races to catch a high fly ballor Advance and transfer vary with eachtype of when a football quarterback throws downfield ship and even with ships of thesame type. Each to a receiver, the players are estimating relative ship, therefore, makes l7ceown advance and 8 378 .!;..pter 5BEARINGS AND MOTION

314

SUB

SHIP SHIP al BEARINGS DRAWING TOWARD THE BOW. 2 BEARING REMAINS STEADY. SHIP WILL PASS T ER N OF SUBMARINE. COLLISION COURSE.

270

280

290.

SUB

SHIP c3 BEARINGS DRAWING AFT. ShIP WILL PASS AHEAD OF SUBMARINE.

71.5 Figure 5-10.Relative motion shuations.

8 I

79 INTRODUCTION TO SONAR

000T In an attempt to evade the attiking ship, the submarine willmaneuver. The attacking ship,inturn, changes course as necessary to reach optimum weapon firing position while

TARGET maintaining sonar contact.Regardless of the number of coursechangesof theshipor maneuvers by the submarine, the job of the operator is to keep the cursor on the target. Correct bearings, ranges, audioresponse, and other target data can be obtained only when the 71.6 cursor is kept positioned puoperly on the target Figure 5-11.Effect of advance and transfer echo. on bearing. DOPPLER AND TARGET ASPECT transfer tables for various rudder angles and at different speeds. Wlren contactis made on an underwater As you can imagine, advance and transfer object,thesequestionsrequire answers:(I) will affect targetbearings during a turn. All Whatisit?(2)Isitmoving? (3)In which possible situations cannot be explained here direction is it moving? because therr are almost unlimited combinations Classification steps, when executed properly, of target and attacker telative mcvements. If the give the answer to the first question. Doppler target is on your port beam, for example, and helpstoanswerallquestions.Doppler,an has the same course and speed you have, when acoustic phenomenon was explainedfullyin you turn left to head for him, his bearing will chapter 3. Remember that dopplerup means the change to the right. Figure 5-11 illustrates the target is headedtowardyou;doppler effect of, vance and transfer on bearing when down means the targetis headed away from the target is stationary or nearly so. you: and no dopplcr means the target is either broadsideto you and neither coming toward BEARING DRIFT you nor headed away, or it is stationary. Assume that you have contact witha submarine. It has Whenthesonaroperatordetectsan doppler, so it must he moving but in which underwater target, he reports the bearing and direction? By this time the ship has turnedto range. The conning officer then turns the ship to head tor the target, enabling you to arrive at the head for thc reported target. As :he ship turns, answer to the third question. 11 doppler is up, the bearing cursor istrained back and forth :.he target is moving toward the ship. If doppler across the target to check for bearing width, and is down, the targetis moving away from the the target is classified. The operator then places ship. the cursor in the center of the target pip. The Theoperator's jobisto determine the cursor shows direction of sound reception. Its direction of target movement and report it.If length indicates range when the cursor line is the submarine is headed directly at the ship, the adjusted to touch the target echo. With the ship target aspect will be direct bow and doppler will headed for the target on a steady course and ata be up. If you are headed at the target and the constant speed, with the cursor bisecting the target has bearing drift the right with no echo, any change in target bearing results from doppler, the target aspectis starboard beau'. target movement. If the target moves to the Figure 5-12 shows the five bask- target aspects right, the operator must train his cursor to the antitheir associateddoppler. The degree of rightto remain on target, reporting "Bearing dopplerisdependent ontargetspeed.For drift right." If the target moves to the left, he example: Doppler of a direct bow target witha trains his cursor to the left, to remain on target, highclosingspeedwouldber,_sportedas and reports "Bearing drift left." 8 5"marked up." Chapter 5 -BEARINGS AND MOTION

Target aspect is best described as the relative or no effect on target aspect of doppler. If the position of the submarine with respect to the ship circles the submarine, however,or if the sound bealn. Perhaps the easiest way a deciding, submarine makes achange in course. target which aspect the submarine is presenting isto aspect will change. A change in doppler is the visualize it in the center of four quadrants and. first indication that the submarine is changing hy the process of elimination, solve for the course,andthischange must bereported proper quadrant. This procedure gives a rough immediately. As soon as the new aspectcan be aspect, and doppler and bearing drift will further determined, it also must be reported. Duringan define the exact aspect. Look at figure 5-13 to antisubmarineattack(orseriesof attacks), see how this solution is accomplished. Assume aspect changes often. 'Me swiar olvrator's job is that your ship is headed for the target and that to detect, evaluay. and re;-.ort each changeas it initially you have a steady bearing with highup occurs. doppler. which indicates that the ship and the submarine are headed directly for each other. N...xt, you detect a hearing drift to the right. COMPUTING TARGET ANGLE with slight up doppler. Quadrants A and Bare eliminated because a target in either quadrant Target angle, whichisa relativebearing. would have down doppler. A target in quadrant gives more precise information on thecourse of C will have up iloppler. but the bearing drift will a ship or submarine than does target aspect, but be tothele Therefore. you would report target angle is more difficult to obtain than is -Starboard bow aspect.- tr.rget aspect. In considering a destroyer making an attack on a submari;h'taxget angleisthe As the ship attacks, she makes minor course relativebearnigIi 1..:,royerfrom the and speed changes. but these changes have little

, SUBMARINE s

STBD PORT sTBp BEAM DIRECT ASPECT PORT STBD BOW - OTR oTr: "cRN B w PORT BEAM

-1- 1

[ IR .T BEARING NONE DRIFT RIGHT LEFT LEFT NONE : EFT

MODERATE mop EATE' DOPpLER uP .10 UP DO\ ^OWN

71 7 Figure 5-12.--Ta(get aspect.

81 S INTRODUCTION TO SONAR

DOPPLER DOWN DOPPLER DOWN

A

BEARING DRIFT LEF-T BEARING DRIFT RIGHT

c, e- sN'' NO DOPPLER NO DOPPLER

BEARING DRIFT LEFT BEARING DRIFT RIGHT

DOPPLER UP DOPPLER UP

OWN SHIP

71.8 Figure 5-13.Solving target aspect.

Imagine that you are on board a submarine 000° to 3600. Likfarget aspect. target angle lookingatanapproachingdestroyer.The depends on the 'sheading. When the relative bearing of the destroyer is 090°, which submarine changes target angle changes indicates itis approaching on the submarine's accordingly. starboard beam. As viewed prom the destroyer, Figure 5-14 illustraws several target angles. ti.2submarine's target angleis0900 because Also shown are angles on the bow (discussed target angleisthe relative bearing of the ship later) and related doppler. Notice that no matter from thetIrget. measured inthe horizontal which direction the ship is heading, the course plane from the bow of the tarnt clockwise from of the submarine governs target angle. 8782 Chapter 5BEARINGS AND MOTION

You may be curious as to why targetaspect thusaffordsameansofreportingreliable is ix) important when target angleproJe., oiore information quickly. accurateinformation.Aspectisgiv,m:Isa Aboard a submarine, target angle is derived general indication and can be reported after only by a method known as angle four or five transmissions, based on the bow (Ab). on doppler and Where:as the ship uses 360° for ,:omputingtarget the first indication of beiring drift. Targetangle, angle, the submarine uses only 1800, specifying on the other hand, is derived frommore precise port or starboard side. To illustrate, data.It a destroyer is necessary to know the submarine's has a submarine bearing 070° relative.Aboard course,whichcanbe determinedonlyby thesubmarine,thetargetanglewouldbe tracking the submarine for severalminutes. In reported as "Angle on the bow. starboard70. many attacks, it is difficult to report an accurate A relative bearing of 345° front shipto target is target angle because of radicalmaneuvers by the reported on the submarine submarine or because of insufficient as "Angle on the time to bow. port15.- Figure 5-14 illustratessome determine targe:Igle. In such instances, target angles on the bow. aspect information necessarily must suffice for Target angle is not all guesswork. It the conning officer to estimate the can he target angle computed accurately by usingthisformula: and adjust own shipscourse accordingly. target angle equals true hearing plus 180' minus In antisubmarine warfare, there is littletime target course. Oxpressed in lire control s:,..mhols. between detection and attaci.. Target aspect the formula r2ads: BtsBy + 180° where = target angle

RELLT,VE EEaR,`,-; By = true bearing '0 DC,..LER Ct = target course.

Assume that you are on a ship and trackinga 6E:.v submarine bearing 270°. 33390 course 135. Find the target angle by appIying the preeediag formula. Thus:

Bts = 270' + 180° 1 35' Bts4500 1350 Bts = 315°

An example of computing this target angleis seen in figure 5-15. In effect. the +1800 in the STEPP4 /4ZIE22DZ'''? DOWN formula allows the viewer tf ,,laces So that he may see hisown

the target. Compare tiie reli c. in' I ;he destroyer from the suhinarii computed for target ar' e. If the producto.By isless than targetcourse.360° be addedto ic equationbeforesubtractingtargetcourse. Example:,\targetis on course 2700. bearing DOWN 0100. Sr4kBGA=.: rpom Bt.,; = 010° + 180' ,05 SL,C,w'r Bts = 190 + 300° Bts = 550' 270° Bts = 280 71.9 Angle on the how (Ab) may he ,:omputed in Figure 5-14.Target angle. the same mannerastargetac, e.with one 83 C'; INTRODUCTION TO SONAR

TARGET SHIP TRUE BEARING CIRCLES

w11111111M1111100,,, ...... -- I

'6.?° .,' a*. C '46 o ,k'.0' % °L, -k g'....e? Bts 5g o CI.. N f=4-eA b 6-2 y g

B y oc: os '4./.,,S'. *-. pe. o0 \0\''''' ';''''' o° 0, '..1/44,61/Tifinirdola\t',\°"* C' o

/1/ 01, *',11,1ii1;y1t cs<, RELATIVE BEARING CIRCLES

45.29H Figure 5-15.Computing target angle. exception. Because the answer is in dep-ees of If the answer is greater than 180°, subtract the relative bearing, it must be converted to degrees answer from 360° to obtain angle on the bow to port or starboard. Referring again to figure 5-15. port. you see that the destroyer bears 0900 true and is Target course c,anbe determined by the course 2400. formula Ct = 13y-tr. (180 ALA If Ab is to port, the resultant of the figures in parentheses is Ab = 0900 + 1800 240c subtracte(i from By. Conversely.if Abis to Ab = 270° 240° starboard,thesolution within parenthesesis Ab = 0300 or starboard 30 added to true bearing.

84 CHAPTER 6

PRINCIPLES OF SONAR

The earliest sonar equipment was a passive systemsinadditiontotheiractivsonars. device, a simple hydrophone lowered into the Submarines, although still relying primarilyon water and used to listen for noise created bya passive systems, aiso employ activesonars. submarine. The only indication ofa target was an audio tone. Bearing accuracy was doubtful, and ranges were strictly guesswork. ACTIVE SONAR

Today's sonar equipments provide highly A simplified active sonar system is shownin accurateranges andbearings.They present figure 6-1. information both visually and aurally.Both active and passive types of equipmentare used. Active sonar systems are used to detectthe presence of ships, analyze shoreline and bottom Alt houghspecificsonarsandrelated characteristics, and determine bottomdepths. erliipments are not covered if, this chapter, basic The basic system consists ofa transmitter, one or more transducers, a receiver, principl..sofoperationsgivenhereinare id displays and applic.Jole to all sonar equipments. controls of various sorts. The transmitterhas a source of power and a r'.2ans for modulating the basic power inam..iner suitablefor the SONAR SYSTEMS particularapplication.Ingeneral,thebasic transmitted power is frequency modulatedas Two generaltypes of scuar systems are single pulses at a pulse repetition frequency(prf) dependent on the system range. employed for the detection of targets. Theyare refer..-.:d to as active and passivesonars. The transmitter power isconverted from electrical to ac,:isticenergy by means of the Active sonars are capable of transmitting transducer for tiansmission of thesonar signal underwater sound pulses i-hat sta.e targets and into the water. Received signalsor echoes are arereturned inthe form otechoes. Echoes reconverted by the same transducer (orby a returned indicate the range ann bcarinc; ofthe d;fferenttransducer in some sonar systems) target. from acoustic back to electricalenergy. The received signal from the transducer isprocessed Passive sonars do not transmit sound. They in a receiver.whcrcvariousamplification, merely listen for sounds produced by the target demodation. and comparison operations to obtain accurate bearing and estim,!!:d are range performed. The output of the receiver, inthe i-ifortnation. form for proper presentation oftarget data. is fed to display and control units. Thedkplays Active sonar systems norm:Jlly ar2 assocated include aural types. suchas loudspea :. and .-vithsurfaceships, whereas passive systems earphones,andvisualtypes, hug Isnally are associated with submarin-s. Newer oscilloscopes. (CRT) cathoderay tut-w:- iuc auface ships, however ,arate passive recorders. and indicator lamps. INTRODUCTION TO SONAR

AMPLIFIER

' 1 COMPARATOR REFLECTED DEMODULATOR , ECHOES ell TRANSDUCER

TRArISMITTED TRANSMITTER F ON A R S.GNALS POWER POWER MODULATOR SOURCE

71.135 Figure 61.--Simplified active sonar system.

Searchli2ht Sonar (Directional) the ship, then the other. It was possible for a submarine to slip by undetected on the port Early active sonars utilized the searchlight side,forexample,whiletheoperator was principlefortransmittingsounds.Likethe searchingonthestarboardside.Moreover, searchlight, the transducer had to be trained to a maintaining contact with atarget that had a particular bearing to transmit sound on that rapidly changing Laring required a high degree bearing. The sound beam was narrow in bearing of proficiency on thepart of the operator. width (about 5°). consequently the echoes were An ot herdisauvan tage was thatsearchlight receivedfrom only a smallsectorofthe equipmenthadonly an audio presentation, surrounding sea. An arrangement of this type whereas today's scanning sonars provide both a was necessary atthat time because sufficient video and an audio presentation. power for omnidirectional transmission could not be generated.The scanning sonarsin Scanning Sonar widespread use todaydeveloptremendous powerenoughto be transmitted360° in Modern submarinesLind ASW shipsare azimuth simultanously. equipped with scanning sonar, which transmits Late modifications to active sonars all°,the sound pulses of high energy inalldirections selectionofdirectionallytransmittedsonic simuitaneously. One of the features of scanning pulses. somewhat relatedinorinciple to`_he sonar is a cathode ray tube (CRT) display of all earlier searchlight sonars. This feature. called underwaterobjects detected in :hearea rotating directionaltransmission,isdiscussed surrounding the ship. Target ec:ines appear as later. bright spots On the CRT. similar to the display The main disadvantage of the searchlight of a radar'sPPI. type of sonar was the length of time required to Some of the data that you may learn from scan the area around the ship. Search procedures thc CRT presentation are as follows: called for the operator to transmit. listen for echoes, train the transducer to a new bearing. I.The size of the target may be estimated transmit, Ikten. and so on. first on one side from the size of the echo. Don't rely too heavily

86 Chapter 6PRINCIPLFS OF SONAR

on thisfea ture.though.becauseecho There are physical phenomena which exhibit appearance depends on such factors as target theability to change electricalto mechanic.il aspect, range. and equipment perlormance. energy and mechanical to electrical energy. and 2.The distance of the echo front thecenter \vhich are emoloyed in sonar tiansdueers.These of the CRT represents range to the objectfrom are the eleetiostrictive. the piezoelectric and the your ship when the CRT is used in the ship magnetostrictiveeffects.Materialsex hibiting center display (SCD) mode. electrostrietive and piezoelectric propertiesare generally of crystal:ine or ceramic 3.True nature. They bearing oftheobjectcanbe change dimensions \viten subjected toan electric determined directly OH the scope. field and develop a voltage potential bet\veen 4.Targe tmovement can be determined two opposite faces when mechanically stressed. from its scope presentation. Fixed objects such Materials exhibiting the magnetostrictive effect asreelsandsunkenshipswillmove ina change dimensions when subjected toa magnetic direction parallel to your ship'smovement and field and change magnetic permeabilitywhen in the opposite direction. Nloving objectsmay subjected to mecharical Llmlge in have motion in any direction withrespect to rmeabilitvchang:s 'ityofany own ship. magnet(,.: field in the pre ,c material.

5.The wake of a submarine oftencan1),.. Variation in the strength of the electricor seen. By examining the wake. you may be able magnetic neld ata frequency iithe acoustic to establish a submarine's headingeven hefore spectrumwillcauseacousticwavestobe its movement he determined by tracking. generated bysuchmaterial.When the transducers are placed in wat:H, suchacoustic 6.Subm,d -!esthatare too far away tor waves can (hen be propagated from the material detection by ecno ranging may yet L'init enough bi ate:. V. nen nind wa,'es impinge upon noise to be detected. Under these conditions,a sucii mdterial after propagation from the small segment of the scope water, appears to be filled themechanicalstress resultingfromthe with a rippling pattern. The general directionol pressure variations will cause variations in the the noise source can he ascertainedy taking field strength(electric or magnetic) which in bearing to the center of the noise pattern. turn generate electric signals in suitable circuits, TRANSDUCERS Magnetostrictive Process

Knowledge of the design and function of the Magnetostriction is a transducer processwhereby isthe keytounderstanding the changes occur in metals when theyare subjected principles of sonar, whether of the scanningor to a magnetic field. Dependingon the material the searchlight type. and the strength of the magneticfield. some A device for convertingonc form of energy materials will expand and.:Mlle will contract, to another is a transducer. In sonar the acoustic hutindependently of,:tedirectionof the energy of thesti.md wavesis convertedto applied field. Nickel is themost :iommonly used mechanical energy in the form of oscidation of material in magnetostrictive it:HISC.:U.cersbQL'aitSC the molecules of the medium through whichthe xhibits a very large magre',-(...trictive effect. sound travels.Theseoscillationscause a NILL1 contracts in a magnetic heldto an extent synchronousvariationinpressureofthe largely proportional to the intensity ofthe field. medium. The sig,ials generated or received by Thenickelelementsin "lie electronic circuits in sonar equipm,snt transducersare are in generallyone-half wavelengthlongandare theformofelectricalenergy.Thesonar supportedatthe transducer acts as the link between the :Lentralnode sothatthe water maximuni amplitude of vibration takesplace at andtheelectroniceireuitsofthesonar the ends.Inonetype 1 tri!nsducer.the equipn.:nt and converts the electricalenergy to elements are niAel tubes. In incwase acoustical energy and vice versa. tiw area 01" the active race in contact withthe water in 87 9 2 INTRODUCTION TO SONAR

this design, a series of tubes or rods are attached toa diaphragm. The diaphi.agin becomes the active face of the transdncel.1-he dimension of , the tubes and the diaphragm plate is designed to make the transducer mechanically resonant at t lie opera tingfrequency formaximum efficiency. Becausethenickelcontractsforeither directionof magneticfield,anapplied ax. sinusoidal field will cause the nickel to con tracl for each half of the a.c. cycle, resulting in a frequency of induced vibration twice that of the appliedField.Inatransducer, the sinusoidal magneticfieldisobtained by winding coils around nickel rods, tubes, or stamped elements (stamped and stacked in various shapes), and impressing a current at the desired sonar signal frequency through the coil. It is generally desired that the vibration and theresulting acoustic signalbc of the same frequency as the electric signal applied to the coils. This is accomplished by superimposing a large d.c. polarizing magnetic field on the nickel elements by means of a d.c. polarizing current 71.48 Figure 6-2.Scarchlightii,lgnetostrictivc V.ansducer. throughthecoilor directlyby permanent magnets. If the d.c. fieldis larger than the a.c. signal field, then the resulting magnetic field will always be in one direction, with its magnitude a metal plate called a diaphragm. hach tube is varying with the a.c. signal. The change in nickel wrappedwith a coilofwiretoprevent element length will thus be synchronous with frequency doubling. When an alternating current isappliedto the coil, the tubes shorten and the a.c. signal. lengthen at the rate of the all.:raating A d.c.polarizing fieldis ako needed for Each tube is polarized by a constant magnetic applicationoftheconversemagnetostrictive field, usually supplied by a permanent magnet. effect.If the nickel elementissubjected to During one half cycic of the applied signal. the varying longitudinal mechanical forces (acoustic a.c. voltage and the polarizing field add: during pressure waves), the resulting stresses change the the next half cycle. th:v oppose each other, and magnetic permeability of the nickel.If a d.c. themagneticfieldisalwaysinonly one magneticfield ispresent,thepermeability direction. ftc contractions of the tubes thus are changes will cause corresponding changes in the fix d to the a.c. frequency. magnetic field intensity. These field changes will Asthetubes contract and expand.the intern induce a varying volt:..,einthe coil diaphragm vibrat.., and produces an acoustic wound around the nici,el clement which will signal of the same frequency as the applied vary proportionally with tfw impinging acoustic alternatingcurrent. A magnetostrictive waves. Without the ambient d.c. polarizing field. transducer used in searchlight sonars is :hown in no voltages will be induced in the coils. figure 6-2_ Inthesearchlight or directional type of Transducers employed withsolll,*scanning transducer,several hundrednickeltubes are sonarsalsooperateontheprincipleof arranged in a circle and mounted on one side of maiiiictostrict ion.Insteadofnickeltubes,

9 3 88 Chapter 6PRINCIPLFS OF SONAR however, the transducer elements have nickel Flectrically,the magnetostrictive scanning laminations pressed in a therinoplastie material. sonar unit acts as two independent transducers Rich clement contains a permanent magnet for housedina eonimon container. One of the polarizingthenickel. Severalelements;Ire independent unitsisthe search section. The mounted verticallytoform I stave, and 45 other is !he maintenance of close vertical staves are arranged circularly contact MC( ') to Corm the section, located above the searchelements. transducer. A scanning transducer isshown in figure 6-3. An exploded view 01a portion of a The search section is madeup of -Is vertical stave is seen in figure 6 4. staves. Filch stave consists of nickel 1..alillatiOns

Many types of o,ieration.il scanningsonar and a polarizing magnet. llectrieall . hi. staves transducersaremag ictostrictive.kxceptfor are independent 01 one another.

vitiriations 1 *111COSi. ii,they are similar in As its name implies, the MCC design. scion is used i type showninfigure6-3isa to maintain contact on a close-in submarine. cylindricalunit The approximately 19inchesin MCC elements transmitill a delayed sequence diameter and 2 7 incheslong.and hasan from the top down, cansinga phase delay 01 the operating frequency of 20 kilz. sound beam, which results inthe top of the beam bending down toward thedelayed portion of the beam. The effectresembles refraction. 'Transmission isat a down v. iird angleof approximately 30'. Because the elements are so placedthat they can cover a 3 60' area, there is no needto rotate thetransducerinscanning sonar.Such an a rra ngcnient providesvideocoverage simultaneously on all bearings. Audio overage is afforded by traininga cursor to the desir. bearing. Most present-da. magnetostrictive transducersarcbuilt along the saMe general lines. Physical chmensionsvary according to the operating frequency andpower output desired. Piezoelectric Process

Thc piezoelectric effect. which isa Corm of ,.trostrietion, is theelectricpolarization produced i-)y mechanical strain incertain classes of erystais. The polarizationand the electric potential induced byitis proportional to the strain and changes sign with it. Inthe cot:verse piezoelectric etct. an electric potentialacross t he crystal face produces a mechanical deformation proportional to the inducedelectric polariz..tiHi: nd ofthe :;:line sign. Pic magnitna,. H this effect variesfor crystals of different materials.. for the clifferent axes of the crystal.

Matcriak most commonly used forsonar transducers have includedquartz,ti, i.49 Rochelle salt (sodium Figure 6-1Scanning magnetostrictive potassium idrtralc I. transducer. ammonium thhydrogen phosph.

8 9 D4 INTROD1V HON TO SONAR

lithium sulphate. Suitahle largc tiar.zt crystals ;ipplications. I urtnaline is used hi. calihration are difricult ohlain. \lost crstal transducep, transduccis het..auscitis rclativcly oi;:...!Tsirov to use Rochelle ...III :Ind ADP hCC:IIISC C lemperatule changes. a strong piezoelectric effect and are easih. grown A crystaltransducer Is constructedhy tothedesired S. liecatINC Rocncdcsalt cementing or mounting a stack of quarter-wave cannot tolerate high temperatures to which j crystals to iheavy steel hacking resonator platc may he exposed during use or storage titwill a I so on e -quarter wave-length thick. The disintegraterroininternalkgeneratedhealit assenthly is mechanically resonant :it the used t(1 transmit Ingh power I'm ;Inv Icn:Ith operdlinr. IrcquenCy with .1 notlit :ittilt.' ifficifacc time),ithas generally heen displaced hv ADI) ol (he phito andcry,;tals,andma \ inium :ind lithium sulphate. Because Rochelle has ;implitude at tlic free end of the cryst;i1s. the strongest piezoclectrk: elfect, itis still II'Ned SincehothRochellesaltandAl)l'are tr,111SLIIIC,r:andforlow-po\cr soluhle in water. the crystal ;isseml,k using !hes,.

f POLARIZING MAGNET

PRESSURE RELEASE STRIP

- I.4hilr4,- IIONS

!s 5 71.50 Figure 6-4.Exploded softy; of one s- !ning ser transduc,:r stave.

90 ChapletIiPR INC111 ( S( )N,A

materials is a sealed enclosm.',1.0 pemnit sound electiostiactiolland Is independent propagation, the elk-10,111e imist be Idled ofthe %).ith dnection (sign I ot theelectric thoroughlydehydratedliquid. heldand Castor ,,!1 is propoi tional to the squaw oi IiHd intensify, commonly used beeause the Lelocityot sound ill IIIthe cr% slat itis almost the same ;is that traiNluceis, the electrostrictive II seawater. tiounkl meetispresentbut propagation from the castor oil 10 linit.:11 .maller than the I lie seil %vat ci piezoelectric effect and is ignored. However, is via a thin metal diaphragmforming the lace oi w i t h F11 11 1 1 Iit It., :C. :1 the transducer assembly, shown I:Cr:Inuit:, IIR' in figure cicknodrictiVe t,'Ict is Lir!'e in compalison with through a diaphragintiltho4nibher he piezoelectric et feet. rubber which has a "c resistance equal to that of the \valet 1. Cerainie fon transduceis has theadvantage too..1- cr), stals in that the When usedfor ceramic can be molded themil \quoin to ;my desired electric signal is produced by the shape. This property is cryst,ilif the p.micularlydesuabl,for frequency of the received sound is making c lindrical tlw same .1". 5oj,I1111111!! Or the resonant frequency or the 011111idirt.*:11011:11llantithiCers. The con% er,,L. ekctrostriction, the Chanr.ein electric rottmlials %Own the materialis stressed. Likes plac.' Electrostri, t' ocess only when :1 constant polarization pot, nti:11 is prcsent. Thea.c sonar signal is thus Whet, Het:1.11Cfi,..1)1isljtc across ;1 supernnposed on the larger d.e.polarization, and dielec." deform:J. I his the material dimension willvary directly with phenol change in diiiiensions is callcd the magnitude of the resultantpotential. The polarization 01 cloctro'drictive materialsis thus ,malogims to the magneticpolarization required f or magnetostrictivematerials.Withoutthe nIAPHRAGM larizatiOn, mechanical .tresses will not CASTOR OIL oduce lii ele, try potenti.H. CRYSTALS all !nsducers now being builtarc of the c, Ceramic: compounds have high sensith ,ty, ruth taH:H.y withchanging temperature andpi ssure, relativHy low costs.

MODERN ACTIVE SONR THEORY

Huethcory or modern activesonar operation best be understood by breaking BACKING PLATE it down into three basic functions: transmission, reception, and presentation. A blockdiagram of 3 representative sonar system isseen ill figure 6-6. The diagram shows only thesystem's major units and ntain signal p.aths.

CP TAL. TRANSDUCER Transmission

-Transmission of the sound poly,:is initiated in the control-indicator, whichis comprised of 71.136 the receiver. audio and video Figure 6-5.Crystal ch-lonels. control circuit,;. and keying circuits.Puise length is also

91 (.;; INTRODUCTION TO SONAR

EC-0NTR-07 A-1-/371 E RECEIVER / SCANNE R

RECEIVER AUDIO AUDIO SCANNING Z- CHANNEL SWITCH SPEAKES

RECEIVER VIDEO VIDEO SCANNING 41 CHANNEL SWITCH

lo.LSWEEP PREAMPLIFIER GENERATOR CONTROL 1 1 CIRCUITS

SCANNING TRANSDUCER

KEYING CIRCUiTS

71.137 Figure 6-6.Basic active sonar system block diagram.

determined at the control-indicator by the sonar cylinder (or sphere, depending on the shape cf operator.Thekeyingpulsefromthe the transducer), which expands in diameter as it c on t roln d icatortriggersthetransmitter travels outward. The thickness of the cylinder oscillatorin thereceiver-scanningsystem walls depends on the puise length selected by assemblyandactuatesthetransmit-receive the operator. (See fig. 6-7.) switch in the audiofrequency (af) amplifier. In the receiver-scanner the pulse is modulated to the equipment operating frequency, amplified, Reception and delivered to the sonar transmitter where it is further amplified to the power level required for If the transmitted sound wave strikes an transmission. object having sufficient reflective characteristics, a small portion of the signal is returned to the The output of the sonar transmitter is fed to transducer. In the transducer, the acoustic signal the transmit-receive switch in the af amplifier, isconvertedtoanelectricalsignalby the then to the transducer transfer switch where piezoelectric effect of the receiving staves. Each selection is made between NORMAL or MCC of the 48 staves has its own preamplifier, located operation. The signal then goes to the transducer in the af amplifier. After preamplification, the where it is converted to acoustical energy and signalis sent to the video and audio-scanning propagated into the water. The shape of the switches in thereceiver-scanningswitch transmitted signal resembles that of a hollow assembly.

9", 9 7 Chapter 6- PRINCIPLES OF SONAR

Thevideo-scanningswitchrotates full deflection is achieved and thesweep is then continuously, thereby sampling noise signals and cut off. echoes from ailbearings. The audio-scanning Rotation of the ss:anner is at such a speed switch is positioned to any bearing selected by tnat you don't see aspiral sweep hut what the sonar operator. Signals from the scanning appears to be an expanding circular sweep. An switches are fed to the receiver section of the echo is seen on the scope as a brightening of the receiver-scanner where they are converted to sweep at a distance from the scope center and in suitablefrequenciesandamplifiedfor a direction corresponding to the target's range presentation. and bearing. During the interval between the, nd of one Presentation sweep and the beginning of the next, the cursor is electronically produced on thescope. Because of the persistency of the CRT, the target echo For the returning echo to be of any value, it remains visible for a short time, allowing the must be presented in such a manner that the operator to determine accurately the target's sonar operator can interpret ithe information it range and bearing. Bisecting the echo with the represents. The echo is presented to the operator cursor givesthebearing of thetarget. By both visibly and audibly. adjusting the length of the cursor so that its tip touchestheecho,thetarget'srange is Themanuallypositionedaudio-scanning determined. switch feeds the signal to the audio portion of Also located on the sonar control-indicator the receiver, which is of the superheterodyne are various switches and controls. Their purpose type. Incorporated in the receiver audio circuits isto givea better target presentation. These is a control for eliminating the effect ofown switches and controls, together with complete ship's speed on the reverberation pitch. This operatingprocedures,areexplainedinthe controliscalledthe own doppler nullifier manufacturer's technical manual supplied with (ODN).Itremoves own ship's doppler effect each sonar system. from target echoes, ueatly aiding the operator intarget classification. From the receiver the Rotating Directional Transmission audio signal is sent to a headset position at the control-indicatorandcanalsobefedto Convention il scanning sonars formerlywere loudspeakers. ofthetype j.c._,t discussed:thatis,only Aftertheoutputofthevideo-scanning switch is processed in the video portion of the receiver, itis dis2layed at the control-indicator on a cathode-ray tube. The sweep on the CRT is PULSE LENGTH a spiral scan, which is synchronized with the video scanning switch. (See fig. 6-8.)

One method of obtaining a spiralscan is to rotate the field of the deflection coils around the CRT, simultaneously applyinga sawtooth SOUND CYLINDER voltage to the coils to cause displacement of the sweep with each succeeding rotation of the coil. For clarity of explanation, thecoil yokeis mechanically connected to the video-scanning switch. As the video.scanner and deflection coil rotate, the sawtooth voltage causc the sweep to 71.52 spiral outward from the center of the scope ata Figure 6-7.Pulse length determines thickness nf linear rate. On reaching the scope's outer edge, sound cylinder.

93 f) 8 INTRODUCTION TO SONAR

o in n idirec.ional transmission waspossible. selectedbearing, depending onthetype of Modern sonars have an operating feature called operation chosen by the operator at the control rotating directional transmission (RDT), which unit. operates on a principle similar to the searchlight type of transmission. The RDT provides greater PASSIVE SONAR t ransmittedpowerthantheconventional scanning type,affordine improved sensitivity Passive sonar, as its name implies, depends and detection range. entirely on the target's noise as the sound source instead of the returned echoes of a transmitted At any instant of RDT, the sn2.nalis the signal.Target detectionisachieved atgreat resultant of phased excitation of several adjacent rangesthroughtheuseofhighlysensitive transducer staves,resulting ina sourcelevel hydrophones. improvement that is characteristic of directional Although passive sonar is usually associated transmission. Excitation of the transducer staves with submarines, many surface ships now have a is caused by the output of a transmit scanner, passive system that utilizes their active sonar which operates much likethe video-scanning transducers. During the interval between sound switchof a conventionalscanningsonar. pulse transmissions, the transducer actsasa Trans.nission is accomplished in a sector (up to hydrophone, allowing the sonar operator to 3000 wide) which is centered on the bow or on a monitor abroader frequency spectrum than

A STEP-BY-STEP GENERATION OP SPIRAL SCAN B SYNCHRONIZING THE SWEEP WITH THE SUNNING SWITCH

71.121 Figure 6-8.Generation of spiral scan.

94 9 9 Chapter 6--PRINCIPLES OF SONAR normally is possible. Passive reception does not the transducer of active sonar equipment when interfere with the reception of pulse echoes. converting sound energy to electrical energy. Duringtransmission,however,thepassive Two generaltypes of hydrophones may be feature is interrupted. employedelectrostrictive and magnetostrictive. Modern hydrophones are of the electrostrictive Hyth-ophones type,consistingofceramicelementsthat operate on the piezoelectric principle. When the A hydrophone is a device used to listen for elementsarestruck by a sound wave, the underwater sounds. In operation itis similar to vibrations set up are converted to an electrical signal, amplified, and displayed at the operating console.

SOUND SOURCE SINGL E- LINE HYDROPHONE.--Knowl- edge of the single-linetypeof hydrophone, although itis not in general us ..!today, will aid you in understandinghow modern hydro phones operate.

Atypicalearlytypeuses themag- netostrictive effectfor sound detection. The hydrophone, which is trainable through 3600, is a line type whose nickel tubes are arranged horizontally in a line. It is divided electrically into right and left halves. SOUND SOURCE Weak signals from the hydrophone are fed to an audio amplifier, then to bandpass filters that remove undesired frequencies from the detected sound. Accurate bearing is determined by training thehydrophone back andforthacrossthe direction of thc sound source. Outputs of the right and left halves of the hydrophone are fed toabearing deviation indicator (BDI). Any phase difference between theright and left SOUND SOuRCE signals causes the meter to deflect. Operation of the BIN is diagramed in figure 6-9. In partA oftheillustration,the hydrophone is on target. Signals in both halves (right and left) produce a phase difference equal to zero. No deflection is indicated by the meter needle. In part B, the hydrophone is trained off the target to the right, and the meter needle is deflectedinthe"trainleft"direction. The bearing deviation indication (BDI) of the meter informs the operator that he must train (push the needle to the left) left to obtain a phase difference of zero. The hydrophonc in part C is 71.54 trained to a position left of the target. A right Figure 6-9.Operation of the BDI. trainis necessary to obtain the desired bearing.

100 95 INTRODUCTION TO SONAR

The majority of passive sonar systems are andthenarefedtoapreamplifiertobe equipped with the automatic target follower amplifiedtoausablelevel.Thereisone (ATF) feature. With the ATI' feature, right and preamplifier for each hydrophone in the array. left sipals are fed back into the training system, The output frOnl each preamplifier is connected causing the hydrophone to follow the target to aslipring inthe compensator switch. The automatically. slipring cmiples the preamplifier output to a HYDROPHONE ARRAY.Modern passive rotor plate. sonarsutilizeahydrophone array, whichis installed in many configurations. The conformal One side or the rotor plate consists of an array is curved around the submarine's hull, with equal number of brushes and sliprings, each an open end aft. The circular array consists of a brush riding on a slipring. On the other side of number of hydrophones arranged vertically in a the rotor plate, a set of brushes is arranged in a circle and mounted in or under the submarine's scale inodel of the hydrophone array. These linearrayconsistsofseveral latter brushes couple the rotor plate output to bow.The the stator plate. The stator plate has two sets of hydrophones mounted along the horizontal axis bars inlaid on the plate, one set on each half of of the submarine. Some of the newer passive the plate. Brushes on the rotor facing the stator sonars utilize a spherical array and in somc cases plate make contact with the bars as the rotor is a towed array. For more information on arrays, trained, and the signals present on the brushes refer to Sonar Technician S 3 & 2, NAVEDTRA are picked off by the bars. Half of the brushes 10132, current series. on the rotor plate arc always in contact with the stator plate, thereby utilizing half of the array at MODERN PASSIVE any given time. The center of the stator plate, SONAR THEORY being the reference point, makes it possible to The theory of modern passive sonar consists determine the exact bearing of' the target. of two basic steps: reception and presentation. The arrangement of the hydrophones causes Figure 6-10 is a simplified block diagram of an the signals to be out of phase with each other at array type of pasive sonar. The array cannot be the output of the preamplifiers. For the signals trainedphysicai!y.Instead, a compensator to be usable, they must be placed in phase with switch is added that, in effect, trains the system each other; hence, itis necessary to delay the electronically. signal. Each bar in the stator plate is connected Reception to lag lines. The purpose of lag lines is to delay the first received signals a proportional amount Signals received ki an array type of passive until the last received signals can catch up. sonar system are coswerted to electrical energy Once the signals arcinphase with each other, they are additive. As a result we have a strong signal to feed to the audio amplifier.

LAG AUDIO There the signal is amplified and then is fed to IND an indicator. LINES M P Presentation

The consoleillustratedinfigure 6-11is represertative of the indicators used with some types of array sonars. Target indications are presented continuously on a paper recorder and 71.55 a CRT. They also arc given audibly. The CRT is Figure 6-10.Block diagram of an array-type passive not located on the console itself, but is a part of sonar. a separate unitan azimuth indicator (fig. 6-12). 0 1 96 Chapter- PRINCIPI 1.S ()IS()NAl;

DIVLAy SELECTOR

35.10 Figure 6-12.Azimuth indicator of an array-type passive sonar.

More detailed information on passiveSO11,11. systems is contained in Sonar n'chnician 2. NAVEDTRA10132.Alsoconsultthe manufacturer's technical manual supplied with each equipment.

VARIABLE DEPTH SONAR (VDS)

As you recall from chapter 3 of this manual, oceanographic conditions frequentlyare such thattherearclayers of water with widely varying temperatures. Where these layersmeet (layer depth). much of atransmitted sound beam is eitherreflectedorsharplybent (refracted). Submarines operating beneaththe layer depth may escape detection because the 35.9 sound does notreach them or because the Figure 6-11.Console of an array-type passive returning echo is greatly weakenedor mushy. sonar. The VDS overcomes this disadvantage becauseit can be lowered beneath the layer depth, thus improvingdetectioncapabilitiespreviously The paper recorder (on the upper portion of limited by the fixed, hull-mountedsonar. the console) plotsthebearing of allnoise. Operating in synchronization with the paper OlderVDSsetsconsistofa towed recorder is the CRT. It indicates the location of transducer operatinginconjunctionwitha all noise-produeing targets by inward deflections shipboard-installed, hull-mounted sonar set. The ofthecircularsweep.An audiochannel. union is accomplished by providing a transducer provided with each azimuth indicator, permits within a hydrodynamic towed vehicle, plusa listening (with the aid of an external speaker) to crane-typehoistforlowering.towing, and this continuously scanning beam. raisingthevehicle(fig.6-13).The towed

97 1 (I "'RODI I( H( )N SON A R transducer is connected electrically to the ship liecallt. of the limited weight-cnrying and through a cable e\ midnig. through the center oi power-producingcharacteristicsofaircraft, the tow cable. A switching inechainsin inthe Ingh-powered a/imutli-type sonar is not carried sonar set permits rise of either the hull-mounted byaircraft.Theequipment is ofthe transducer orthetowed-transducer, or both "searchlight type which pings on one bearing at simultaneously. a time, must he trained to the required bearing to detect a target, and presents only an audible A later typeorVDS (not shown) is a s,)11:11. echo without video presentation.Inspite of setcomplete withinitself.Becauseitcall he these limitations, airborne sonar gear is capable made to operate independently of other sonar of excellent results because it can be transported systems, itis known ;Is the independent variable from one location to another at a much higher depth sonar (IVDS). speedthanthatof any surfacevessel and because, although such aircraft as helicopters are noisy,theyproducelittlewater-conducted DIPPING SONAR noise. (Most dipping sonar presently used in helicopters is capable of scanning 3600 and also Sonar equipment called dipping sonar can of narrowMg the search to a selected bearing.) be used by rotary-wing aircraft (helicopters) to detect submerged submarines. Because itisn't Inahelicopter, the dip or dunking sonar practical to drag sonar equipment through the equipment, except for a hall-shaped transducer waterattheminimumHyingspeedsof housingtire500-foot cable from which itis fixed-wing aircraft, only aircrn.t that can hover suspended, is located in the helicopter fuselage. or move Litlow speeds are suited for sonar When thehelicopter has reached alocation detection. where the presence of a submarine is suspected,

1 0 3 51.63 Figure 6-13.VDS towed vehicle ready for lowering.

98 napier o ll'Llti()I )NAR

it descends to It) to 21) tcel above thewater, .ind continually. 1:01rt: hd 4 shows the sonarhallis a hc11,:(Ipier with koAcredto;ihout 401) feet simar cuhmerg.ed. sealchim). belowthesurface.Aftersearching,the helicopter hauls In the cable. After theeahle has SON0131.1ON'S been retracted, the helicopter can go to ;mother Radioso;lobiloysaresmall location. When the submarineis detected ann expendahle located,the hehcoptcr can "vector in" other hydropII,)neunits,VhOseolllputis radio-broadcast by aslltallIrulsmit lerinthe aircraft and ASW vessels for theattack or can sonohuoy. They zlle itself attack it' properly armed. generally dropped to thesea surface hy fixed-wing ;nrcrat'tin thk ;trea where l'he search procedure enemy submarines are expected to be. Usually can he completed in a more than one is dropped at a tillte, in few minutes (especiallyif a L'IrCuldr the search doesn't pattern around the contactarea (as (ietermined encompass thefull 360in azimuth), and the byotherdetectiondata).Anexperienced helicopter can be up and away. Presenttypes of operator, hy com)aring its pitch (for(ioppler) as submarines have no effectivecountermeasures received by each sonohuoy, againsthelicopters.This search can estimate the techniqueis present location and direction ofmovement of much more difficult in heavy weatheralthough the target. After two to lour improvements inthk respect are being made hours, a soluble plug inthe sonobuoy dissolves and allowsthe

1HF NAV Y"7:

--- ...r.,?, . ...----f.7-_-;:--....-7f-t-:.,1----.-:

;74, '-'' -----7.-':" 7 7j .St '' 14.. #: .2 : 0.,'Jr7,41.M. .. . 4 .. 2 ' ... 4: , . ; . .I. 2:...... : a ' .."..*4 ...... -..,/... , .."..,..,,,E.ye, ....t.

7:.....:.;r7: 7" '

g *Irt

3.115 Figure 6-14.Dip sonar in use by helicopter.

99 104 INTRODUCTION TO SONAR

thespeed of soundinwater,the depthis thereby determined. Such an echo sounding device is known as a sonar sounding set called a fat hometer or a depth sounder. Basically the fathometer isa navigational instrument: but, becauseitoperates on the sonar principle,it usuallyisgivento the Sonar Technician for upkeep. One type depth sounder used aboard ships and. submarines is theAN/UQN-1sonar sounding set, showninfigure6- I 6.Several models of the set are in use. The AN/UQN-1 depth sounder employs the LAY TWO BUOYS AT rHE APPARENT ORIGIN AND A hotstylusandsensitizedpaper method of THIRD IN THE PROBABLE recording depths.Italso has a visual scope SLICK DIRECTION OF SUBMARINE MOVEMENT presentationfor shallow depths. This depth sounderisa compact unit, capable of giving

110.106 Figure 6-15.Radio sonobuoys used to locatc submerged submarines.

unittosink.Whileafloat,thesonobuoy RECEIVER -TRANSMITTER indicates its position visually (by releasing red dye into the water or by keeping a lamp lit) and by radar. Figure6-15 shows diagrammatically how one type of sonobuoy pattern is initiated by an aircraft in response to surface indication of the presence of a submerged submarine (in this case, the oilslick from a subma7ine that has been damaged). The buoys are planted where they win continue to pick up the submarine's sound as it proceeds underwater. A frequent pattern is acircle of buoys about the area (called the datum)inwhichthesubmarine contactis expected. TRANSDUCER

DEPTH SOUNDER (FATHOMETER) The use of sound is a common method of measuring .water depth. A sound pulse, directed toward the bottom, is transmitted, and its eche is received. The time between pulse transmission 62.9 and echo reception is measured and, based on Figure 6-16.Depth sounding equipment.

100 1 6 5 Chapter 6 1S OF St)N,AR

- 560 TRANSMITTED PULSE TRACES lop° rc\O

1500 15.1

260 200a tit 200 TRACES MADE ON 250 2*0 6000 FATHOM " SCALE 300 3000 300

3500 350

4000 400 ,tcoo .lio TRACES\ MADE ON TRACES MADE ON 450 -100 450 600 FATHOM ,-1.), 600 FOOT SCALE SCALE r I 500 5600 !:000 /

i -51:0

1 i",tOr 6000 I vl t,(*i

62.10 Figure 6-17.Depth recording showing a steady decrease in depth. accurate readings at a wide range of The recordingillustrjtedwaS 111,1L rrolll a depthsfroni about 5feetto 6000 fathoms. ship sa hng over a sk2:1 with steadily decreasing Threerecorderrangesareprovided onthe depth. The first part of the trace was recorded AN/LIQN-1. They are 0 to 600 feet. 0 to 600 onthe6000-fathomscale.Inasmut.h:isthe fathorns. and 0 to 6000 fathoms. The CRT paper mov..s from right to lett. you can see in ranges are 0 to 100 feet and 0 to 100 fathoms. the section of the pryer shown that the depth The equipment may bekeyed manually or decreased from 4000 to 600 fathoms.( Eater automatically. (NOTE: All depths are measured depth information is to the right o) the paper.) from the ship's keel, not the water's surface.) When rdepth was about 600 fat'Jams, the scale Two styluses are used, hut they are spaced was shifted to the 600-fathom setting. (See how so that only ono stylus records at a time. When shifitrig makes use again of the entire width or the depth sounder records, a stylus starts down the paper.) Because depth decreased still further. therecorderchartsimultaneouslywiththe thescale was shifted to the 600-foot setting transmissionpulse.Thestylusmovesat a whenadepthof about100 rathows W s constantvelocity and marksthepaper recorded. twiceonce at the top of the chart, when the The marking onthe paperis downward pulseistransmitted. and again on the depth (stylus !notion is downwa.t1) in alternate rows indication when the echo returns. A depth printed from 0 to 600 and 0 to 6000. Ntarking recording made by a depth sounder of thk tpc the chart paper in this mariner rillows the Sallie is seen in figure 6-17. paper to he used for all recorder set(ings. You

6 101 IN1101)1V1.1(1N in

HMS( 111101 ,,C;1 le theequipment is 111:1he 11hctlicr the marking is in thousandsot fathoms,hundredsot fathoms, or hundieds of feet. 0 BC sk.*:11(' ii Ike K ,,reatcr (Lin thewaterdepth.Otherwke,a falsedepth indication (Or no indication willresult, depending on the position of the stylusesat the : tnne of echo return, If water depth actuallyis 120 feet, for instance, imd you have selectedthe 100-foot range scale, a depth of 20 feet willhe indicated. .- Other fake indications are multiple echoes s`N and reverherations, both of which usuallyare limmuiLLli'/hi caused bytoohighagainsetting.Multiple echoes are the resultof the transmitted pulse being reflected back and forth several times between the hot tont and the ship's keel.In shallow water asolidline may he recorded, making itimpossible to read the depth. Both 71.57 multiple echoes and reverberation effectscan he Figure 6-18.--Visual depth indicator. reduced by decreasing the gain. Visual im.hcation is supplied by a circular 2.On the range switch, select theproper sweep on the face of a Transmitted pulse range scale. On the indicator the scale is either andreturningecho markthesweeptrace 100 feet or 100 fathoms. On the recorderthe radially.The visualindicator,pointing toa scale is 600 feet. 600 fathoms,or 6000 fathoms. depth of 82 feet or fathoms (dependingon the scale setting fis shown in figure 6-18. 3.Set the ping switch to AUTOMATIC. 4.Turn the gain control clockwise untila Operational Procedure suitable echo mark is obtained. 5. Followingis a brief discussion on normal Observe that both styluses attached to the revolving hell mark thepaper from the zero operation. securityoperation. and shutdown line to 5 feet. procedures, Refer to figure 6-19 while reading this description. 6.Checktoseethattheproper range marking is indicated on the top of thepaper. NORMAL OPERATION. -Eor simplicity, it 7.Dep:-ess marker hutton. Observe thata may be assumed that there is only one normal straight line is drawn down the full length ofthe way of operating the depth sounder, Deviations paper. This line should be straight from top to may be considered as expedients for conserving bottom.otherwise thestylus is outof electricalenergy,time,orpaper,orfor mhustment. maintaining sonar security. SECURITY OPERATION.-- Ifitis not I.Move power switch to STANDBY. wait desired . toplace linked energy inthe water about 30 seconds, then ihrow the switchto ON. periodically, the depth soundermay be operated This proc,..dure prolongs the life of the keyer IS lornormal operation, except that the ping tube by allowing the filament to heat hefore switch is triggered down \\lard to SINGLEPING. applying plate voltage. thenisreleased. The circuitry 0 7 is arranged to 102 (li,uptt' H 12k1NC11211S 01St pulse the first link' the ke iw, contaA: Operate I Illpwation ftenteiI.1 his ;Rtion Ikconnock after trirgerinr and then to release ininickh,ikl. both ,,ikIest)IIhe 1 I -)-\HI, h0Il.\ripply trom The ping switch way he held down as long, a, the c,unpinent (e \cep) thc ,,cl% lc,. mulletI. desired without damage. The resultis e\actls thesameas ii thkswitchw'ercin the Rtmtine Maintenance AUTOMATIC position. Pontine iimintLmank:e use1lick'applies to SHUTDOWN. Putthepinr switchinthe knictions.hesidesopciation.thatshould he ()IT position. Throw the power switHi to the perrorined h the operator, \VIftn the operator

7. H','1 i) ON AruD VvAl 130 '..:,F,CYNOS, Ok 7,100W ro SI'ANDHY IF IN': rAN.TANEOJE. :70 :.,ELECi Ail 1-,)%1A TIC OH SINGLE OPFRATLN MAY RE RK::WIRED IMMINENTL`T' PV.:G

SELECT INDICATOR OR RECORDER AND ADJUS IGAIN CONT ROL TO GET PROPER DEPTH RANGE A GOOD ECHO

.." "- 1 Q FArHONIS FATriv,e,:-P POWER i00 5000 HEADPHONENiAPI. FR FEET / FATHC.: ON \\14[JF:imAFIC

l'ING K11) i OFF (*1, °C1 ,...... " STANDf3v S.NGLE PING ri:NOE ILLUMINATION GAIN

, 2S0 IS2 5.151 n4,-, 150 , 0 ) Di. c voc vac .nt

ci

5 6 ADJUST ILLUMINATION USE TO MARK VERTICAL LINE ON CONTROL TO SUIT RECORDER CHART FOR TIME SURROUNDINGS IDENTIFICATION

71.58 Figure 6-19.--Depth sounder control panel. INTRODUCTION TO SONAR

checks out depth sounder equipment beforea Originallythe AN/UNQ-7 had recording run, he should be prepared (if necessary) to speeds of 3-3/4 and 7-1/2 inches per second make minor adjustments and replace lamps, (ips).Field changes permitted an additional tubes, styluses, or paper. Moreover, he should be speedof 15ips.Allsubsequentmodels, satisfiedthattheequipmentwillrender beginning with the AN/UNQ-7A, have the 15 ips continuous satisfactory performance during the featurebuiltin.Ingeneral,thefasterthe anticipated operating interval. recording speed, the more faithful is the sound The manufacturer's technical manual that reproduction. accompaniestheparticulardepthsounder The standard reel is 7 inches in diameter, aboard your ship lists a step-by-step procedure holding1200feetof1/4-inchtape.At a for accomplishing minor adjustments, replacing recording speed of 15 ips, 1200 feet of tape will parts, and satisfying preventive maintenance last about 15 minutes. requirements. Operating Principles TAPE RECORDER Magnetic tapeconsists of finely ground SonarTechnicians,particularlyaboard iron-oxideparticlesdeposited upon a plastic submarines, must be able to make rec. -rdings of backing (tape). The particles, too small to be sonar echoes and of other sounds detected by seen with the naked eye, are deposited in such a the transducer or hydrophone. Such recordings way that they are allowed to mapetically move are valuable aids in classifying sounds (determin- or line up in an orderly fashion as a result of ing the nature and/or source). All ships and some force applied to them. The force having submarines aresuppliedwiththenecessary equipment to make such recordings. The most commoninst al lation is theAN/UNQ-7 recorder-reproducer sound set, familiarly known as a tape recorder.

The AN/UNQ-7taperecorderismore sophisticated than many commercial types. It is atwo-track recorder and reproducer, and is responsivetoallfrequenciesinthe audible range.Both tracks may be recorded either simultaneouslyorindependently.Normally, track B is used to record signals directly from thesonar equipment. Track A isused for recording voice information.

Whenarecordingreproducedbythe equipment is played back, both tracks can be heard, or only one track, each channel having its own volume control. In short, the AN/UNQ-7 acts as a combination of two separate recorders thatare capable of being coupled to allow superimposing two audio information channels upon each other. Figure 6-20 shows the front panel of the recorder. Later models, namely the -7B, -7C, -7D, and -7E are transistorized and have a somewhat different appearance, but their 3perating characteristics are the sameas the 7.54 )asic model. 109 Figure 6-20.--Tape recorder AN/UNQ-7.

104 Chapter 6PRINCIPLES OF SONAR such an effect on the iron-oxide particles is a The recorder has three heads. The device in magnetic field. This magnetic field can be caused the recorder about which the magnetic field is bya common magnet or by atemporary produced bythemicrophoneiscalled the electromagnetic field.Itresults from passing recording head. Another head, called the erase an electrical current through a coil of wire. head, eliminates the magnetic pattern from the particleson thetape. A thirdheadisfor playback of the recorded signal and is called the Magnetic Heads reproductionhead.Thethreeheadsare contained in a single housing. A microphone contains a magnetic device thatis capable of producing electrical energy RECORDING HEAD.The recording head representative of the sounds spoken into it. In a is composed of a highly permeable material, t a pe recorder,themicrophone-produced which means that the core is easily magnetized electrical pattern is fed to a wire coil, causing a and just as easily demagnetized, by a current magnetic field which represents the pattern. The passing through the coil. High permeability is a coil is wound on a core that has a gap in one necessity for the magnetic field to follow the side. Because the magnetic field is most intense fluctuations of the signal to be impressed on the at the gap, that is where the signal is placed on tape. the tape. The narrower the gap and the sharper In reality, the signal cannot be put "as is" the gap edees, the better is the high-frequency directly onto the tape. It must be mixed with response. Figure 6-21 shows a typical maenetic another signal for strength and linearity; that is, head. The magnetic tape passes over the head, for consistent form throughout the signal band. and the electrical pattern is reproduced upon the The bias signal with which the original signal is tapeintheformofregularpatternsof mixed is of very high frequencytoo high to be iron-oxide particles that magnetically line up in heard.Electrically,it hasunchanging, accordance with the signal passed through the steady-strengthcharacteristics.Thea.c.bias coil. assures better acceptance by the tape of the signal to be recorded and helps reduce distortion of strong signals. GAP ERASE HEAD.Tape passes from the erase head to the recording head, and then to the reproduction head (inthat order). The erase headdemaanetizesbothchannels simultaneously. It is unnecessary to erase a tape individuallybeforeitisre-recorded because, when a tape is being used for recording, the erase head is energized so that a new recording cannot be ruined by superimposing it over an older one. Thus, tapes having recordings that no longer are neededt'orretention can be used directly. The machine simply is set to record; the old tape is put on; and, after it passes the erasehead,itis"cleaned" of theearlier recording.Itnext passes the recording head, which puts a new magnetic pattern on it. REPRODUCTION HEAD.The reproduction head, whichisnextinline,is 71.122 similar to the recording head in construction. Figure 6-21.Typical magnetic head. Thatis,ithas a broken ring of permeable

105 INTRODIJCTION TO SONAR

material wound withwirecoils. When the Next, select the speed at which recording is recorded tape passes over the gap, the permeable desired. As mentioned earlier, there isa choice materialis affected by changes in the tape's of 3-3/4, 7-1/2, or 15 inchesper second. Select magnetic field, and an electric current is induced the faster speed for critical recordings during in the coils surrounding the ring. The induced which thepitch of the echo may have an signal is amplified and fed to phone jacksfor important part in later evaluation. A recording audible presentation. made at a higher speed can be studiedmore completely by reproducing it at the lower speed. Operating the Equipment (An 800-Hz tone, recorded at 7-1/2 inchesper second, is heard at 400 Hz when reproducedat The top half' of the tape recorder,as seen in 3-3/4 inches per second.) Hence, recordingsthat figure 6-20. is the . actualrecorderand may require later analysis should be made at the reproducer. The lower portion is the amplifier higher speed. The disadvantage of the higher section. It includes controls and indicators that recording speed is that the tape is used twiceas directly affect the recording and playback ofthe fast as when operating at the next slower speed. tapes. Information on speeds to use for recording and Each recording track has a separate channel. playback are contained in the technical manual On the equipment they are labeled channelsA supplied with each recorder. and B. Channel A is used for voice recordingand reproduction; channel B, for sonar information. Althoughthehigher speed providesthe Bothchannelshaveseparatecontrolsfor highestqualityreproduction.differencesin recordingandreproduction.Therecording recordings made at each speed are not detected :ontrols are to the left of the amplifier section. easily. Only when acriticalanalysis of the Playbackcontrolsareattherightof'the recording is made does the faster speedprove its implifier section. worth over the slower one.

THREADING TAPE.The roll of magnetic The recording level is selected next, and each 'ape to be used for recording purposes is placed channel's level must be adjusted individually.An )ntheleftreel-hold assembly on theupper indicator on the amplifier assembly is labeled ection of the recorder. Itis placed in such a RECORD LEVEL INDICAT3R. Directly below vay that, when the equipment is in operation it isa two-positiontoggleswitchlabeled CHANNEL SELECTOR. The positions of recording or reproducing), the reel rotates ina the 'ounterclockwise direction, and the magnetic switch are marked A and B, each representinga ape leaves the reel from the bottom. channel. Set.the toggle switch to either channel, Other parts are on the upper section to guide and observe the vertical amplitudeon the face of he tape and to pull it through the head device. the indicator. The record level controls, below the CHANNEL SELECTOR switch, /hen the tape unwinds from the left reel, itis are marked [-treaded around the guiding assemblies, fed for channels A and B. Adjust the level control 'irough the head assembly, around the capstan for the channel chosen until the signalpeaks mhich actuallypulls the tape through), and (shown in the level indicator)occupy the space ien itis taken up by the ridit reel. A pictorial between the upper and lower horizontal lines. iagram of the path followed by the tape from Next, select the other positionon the switch and !el to reel is printed on the face of the head makethesame adjustmentsfortheother ;sembly. By adhering to the diagram.you will channel. The equipment is now readyto record we nodifficultythreading the equipment on both channels. roperly. To start the recording process,an unlabeled button to the right of the record level indicator RECORDINGAfter the tape is threaded, is held to the left, and the tape recorder le tape recorder is energized by turning the control (record section)ismoved up to the No. 1 mer switch to the ON position. You must wait position. A ligbt (indicator No. 1) glowsas the a short warmup period. equipment begins to record.

106 11 1 Chapter 6PRINCIPLES OF SONAR The unlabeled button is called the record automatic erasure process during recording) if safety interlock switch. Its function is to prevent the switch at the remote control unit is set to accidental or inadvertent recording. To record, therecordpositionduringplayback. you must place the record switch in the No. I Consequently, the switch on the remote control position and simultaneously turn the record unit must never be moved from the standby safety interlock switch to the left. position unless the standby light is glowing.

To stop recording, set the record switch to Whenthemachine is recording,the the neutral (middle) position. To start recording RECORD lighton the remote controlunit again, move the safety interlock once more to glows.Whenapproximately 5 minutesof the left as the record switch is returned to the recording time, at 71/2 ips, remains on the tape, No. I position. the RECORD lamp flashes to warn that the end of the reel is approaching. If the recorder cuts Another position of the record switch is out (this feature is automatic when the tape reel labeled AUX (for auxiliary). This positionis is exhausted), the RECORD light goes out. When providedforuseifanauxiliary the tape recorder returns to a standby condition, recorder-reproducer is added to the system. the STANDBY light glows again.

RECORDING FROM REMOTE REPRODUCING.Toplay a recording,- LOCATION.Adevice that allowssome thread the tape, turn on the power switch, allow control of the assembly from remote locations is for warmup, and chose the tape speed. includedwiththetaperecorder. single operatingcontroland two indicating lamps Next. place the REPRODUCE switch in the (labeled STANDBY and RECORD) are on the No.Iposition (it has the same positions as the remotecontrolunit.Thesingleoperating RECORD switch). This setting actuates tape controlisatwo-positionto,mle switch that motion, andbothchannelsarereproduced parallelstherecnrd switch on the amplifier simultaneously. section. Prelimin. :Itstments, such as tape threading and levt:-,trol, must be set before Finally, adjust the reproduce level controls using the remote control unit. The standby light for both channels to the desired output of each indicates that power has been applied and that of the headphones (if used) or the loudspeaker. tape is threaded. It does not signify selection of the proper speed nor adjustment of the level To stop the playback, simply return the controls.It does not light when no power is reproduceswitchtotheneutral(middle) applied, when the tape is threaded improperly, position.Thisstoppage may occuratwill nor when the equipment is used to reproduce a throughout the run of the reel. The equipment previously recorded tape. returns to the standby condition whenever the neutral position is selected. As in the recording Thepositionsof thetoggleswitch are mode,thetape motion stops automatically STANDBY and RECORD. The standby position when the end of the reel is reached. corresponds to the neutral position of the record switchontherecorder proper. The record Remember that the switch on the remote positiontakes precedence at both locations, control unit must not be set to record during the meaning that, if RECORD is selected on the repioduction mode of operation. Otherwise, the remote control unit, the equipment will record recording will be ruined. even though the record switch on the equipment proper is in neutral. If RECORD is selected on the instrument proper but STANDBY is set on Other Uses the remote control unit, the equipment will record again. Thus, a tape being reproduced on Thetaperecorderallowssimultaneous therecorder proper can be ruined (by the recording and reproducing of sounds. By this INTRODUCTION TO SONAR means, you can monitor what is being recorded A switch ontheupper section of the as it is recorded. Steps to set the equipmentto this mode of operation instniment allows rapid rewindand fast forward are included in the operation. Instructions andprocedures for using equipment iniruction book, TechnicalManual, the switch, as well Recorder-Reproducer Set, Sound, AN/UNQ-7, as those for erasing and splicing thetape,arealso includedinthe NAVSHIPS 365-2471. instruction book.

11 3

108 CHAPTER 7

BASIC FIRE CONTROL

Although the overall objective of all Sonar FCS. The discussion following does not apply Techniciansistoaidindestroying enemy specifically to all FCSs on all ships: the aim is to submarines, the manner in which the taskis describe the main elements of most systems so accomplished varies with the individual branch that you will understand their functions and of the rating. The shipboard Sonar Technician, how they work together. forexample,triestomaintaincontinuous Thebasicfirecontrolattackproblem contactandaggressivelyentersthe consists of analyzing target motion from sensor submarine/ship duel, using every available means inputs,determiningfuturetargetposition, to hold contact. The submariner has a tendency selecting the optimum weapon, and generating to sneak up on the target, gathering attack launching orderstodeliver the weapon and information from the noises produced by the destroythetarget.Weaponselection is targetitself,perhapsmakingonesonar determined from target data and the computed transmission just before firing. In each instance, tire control solution. Various units of the FCS the ultimate goal of the antisubmarine unit is are: ) apositionindicatortoallow for destruction of the enemy submarine. The system command controlof weapon selection and by which information is collected and translated tiring, (2) a stabilization computer to stabilize into weapon firing data (including positioning of launcher and sonar during the attack problem, weapon launchers) is called fire control. (3) one or more position indicators to allow testing, setting and monitoring of aselected weapon andtoactasacompatibilitylink UNDERWATER FIRE CONTROL between gun fire control radar and the attack console, and (4) the attack console, the central Fire control is defined as the technique by data processing center of the FCS. which weapons are directed to a selected target. It consists of the material, personnel, methods, communications, and organization necessary to Attack Console destroythe enemy. Underwaterfire control includes all of the foregoing components, with The attack console is a computer in the data the added difficulty that the selected target is a processing center of the FCS. In addition to submarine,capableofmovingin three receiving target data from sonar, it may be able dimensionsin range, bearing, and depth. to act on target bearing and range from missile or gun FC radars. REPRESENTATIVE UNDERWATER The console receives information such as (1) FIRE CONTROL SYSTEM own ship's course and speed, and (2) target range, relative bearing, depth, course, and speed. Because many operational aspects of specific There may be other inputs, depending upon the fire control systems are classified, this section type of weapon to be launched; most inputs are describes in general terms the functions of what generated electronically, while others may be may be considered a representative underwater insertedmanually. The console displaysthe INTRODUCTION TO SONAR

attackproblemontheconsolegeographic information; an indication of firing readiness; plottersection, combining tamt data with and for some weapons a control by which the ballistic's and own ship's motion to provide commandingofficerapprovesthepayload (depending on the weapon to be employed)-- selection. For the last, unless command activates the"approved"control,the attackconsole G:erated data for sonar tracking and cannot generate a firing command. position keeping. ?.Launcher train and elevation orders. Relay Transmitters 3.Missile or torpedo set-in orders. In general, relay transmitters receive input 4.Range and bearing for torpedo attacks. data at a particular Irequency, then convert it to a 5.Directordesignationforin-flight different frequency (operating voltage) for tracking. transmissionto other equipments. There are many types of relay transmitters, depending on From received target motion quantities, the thepurposefor whichutilized.Thisbrief discussion, of course, console computes aided sonar bearing, andrange is concerned only with tracking information and sends it tosonar. If FCS relay transmitters. sonar loses contact, the operator places the Onetypeofrelaytransmittertests, consoleintheposition-keeping mode, and programs,andmonitorstheignitionand attack problem computations continue from the separation assembly data of a selected missile. last observed t-t range, bearing, course, and After the missile is selected, the transmittertests speed values y entered into the computer. the power supply, thrust cutoff velocity time Dependingonwhattheinputstothe channel, and airframe separation time channel to computerare andtheweapon(s)tobe ensuremissilereadiness forfiring. missile controlled,theconsolesolvestheattack check results are unsatisfactory, another missile problem and transmits to the weapon the firing must be selected. signal and the stabilized weapon train angle. lt A second type makes the attack console also transmits to the bridge the course to steer compatiblewithgunormissileFCSs and forthe attack. (More precisely,itputs out weapon direction equipment. This transmitter is corrections to own ship's course.) used during (I ) missile or target tracking and (2) missile designation.Fortheformer,the Stabilization Computer transmitter converts single-speed synchro target or missile bearing data into two-speed synchro The stabilization computer receives roll and signals for transmission to the attack console. pitch data from the ship's gyrocompass, target When thetransmitterisutilizedformissile bearing from sonar, and apparent depression designation, water entry point quantities and anglefrom the attack console. From these airframe separation time are received by synchro quantitiesthecomputer generates stabilized transmissions fromtheattackconsole. sonar train and depression orders and transmits Designated missile elevation is set in manually at them to sonar. Input and output stabilization the relay transmitter. data are displayed on dial indicators on the front panel of the computer. WEAPONS

Position Indicator Some of the antisubmarine (A/S)weapons controlled by underwater fire control equipment A position indicator on the bridge provides and used by ships and submarines againstenemy command with an indication of the source of' submarines aredescribedinthetopics that contact (sonar or radar); a continuous display of follow. The discussion also points outsome of ownship,target,and weapontactical the problems that must be overcome by the Ho 115 Chapter 7BASIC FIRE CONTROL underwaterfirecontrolsystemtorealize speeds of many modern submarines, was slow, success. Since these weapons were presented in and they could be outrun by submarines. These chapter 2 of this manual, the discussion is brief. drawbacks have been eliminated for the most Not all weapons are discussed because of the part in modern high-speed torpedoes. The newer nature of their classification. torpedo also is quite maneuverable, in contrast tothe submarine, and has a tighter turning SURFACE A/S WEAPONS circle.Except for attempting to delude the torpedo with a decoy-type device, one of the best defenses the submarine skipper can provide Aboard ship, several kinds of antisubmarine against a modern antisubmarine torpedo is to weapons arc available. The principal one is the call for all available power in an effort to clear ASROC utilizingtorpedoordepthcharge the area at maximum speed. Even then, modern payload. Also included are one of two types of torpedoesarenormallyfasterthanthe above water torpedo tubesthe Mk 32 triple submarine.But,inasmuchastheprimary mount(see fig. 7-1),orthe Mk 32 mission of an A/S escort vessel is to prevent the superstructure-mounted doub!f: moant (see fig. submarine from making an attack, causing the 7-2). submarine to evade a torpedo and rur from the Homing torpedoes are of two typesactive area would accomplish the escort's mission. and passive. The active type transmits sound When conducting an antisubmarine torpedo pulses and homes on the echoes reflected from attack the ship must maneuver into a favorable thetarget. The passive type is guided to the launching position. A typical homing torpedo target by noise emanating from the target itself. runsin helicalpatternswhileseekinga submarine. Once contact with the submarine is Earlyantisubmarinetorpedoes had two achieved, the torpedo steers toward the target. If- ;erious drawbacks. First, the endurance or active contact is lost, the torpedo searches for a short Jeriod was relatively shorta matter of minutes. timeinthe general directionin whichitis 'Second, their speed capability, compared with running, then resumes a helical search pattern if

retti.

3.129 Figure 7-1.Mk 32 torpedo tube. INTRODUCTION TO SONAR contact is not regained. Some types have a Althoughthestraight-runningcontact passivecapabilityinconjunctionwith their torpedoesareuseful incertaintactical active feature which enables them to detect a situations, they are not considered effective as submarine that is beyond their active acoustic antisubmarine weapons. These torpedoes are range. used chiefly against surface targets at fairly short The shipboard antisubmarine rocket, known ranges. They are noisy and thus are detected as ASROC, was discussed in chapter 2 of this easily, but they are difficult to counter because manual. of their high speed. Acoustic-homingtorpedoesavailableto SUBMARINE A/S WEAPONS subnwrines have features for homing passively or actively, and for combining the two. Today's submarine has a choice of many Wire-guided torpedoes are a variation of the types of torpedoes, each designed for a specific acoustic-horning torpedo. They are guided to the purpose. The three main classes of torpedoes are target submarine's vicinity by signals sent over straight-running,acoustic-horning,and the wire by the launching submarine. After the wire-guided. target is acquired by the torpedo, it homes on

7 3.129 Figure 7-2.View of Mk 32 Mod 9 surface vessel torpedo.

112 Chapter 7BASIC FIRE CONTROL

the target without further guidance from the surfaced submarine and that the disappearance launching submarine. was caused by diving. If sonar contact also is The submarine also has a rocket-propelled held,itcanbe assumedthecontactisa weapon, containing a nuclear warhead called submarine. Mostsurface-searchradarscan SUBROC, which was described in chapter 2. receive aradar indication from a periscope. Hence, it ic possible to track a submarine that is operating completely submerged except for its DETECTION-TO-DESTRUCTION PHASES periscope. The radar method goes hand in hand with visual detection because radar frequently Theoretically,thefirecontrolproblem provides the first indication, directingeyes to begins when a target is detected and ends with the location of the periscope, snorkel, sail,or itsdestruction.In practice, though, the fire hull of the submarine. controlproblemstarts well afterinitial detection.Itcommencesaftertheinitial The sonar equipment aboard your shipor classificationandwhentargettrackingis submarine is designed to detect and track the ordered. submarine and feed computing devices with tactical data to achieve the destruction phase of Likeallotherfirecontrolsystems the problem. (antiaircraft, surface-to-surface, and the like), the antisubmarine fire control system solves the problem in the following stages: (1) tracking the TRACKING PHASE target(2)analyzingtarget motion and (3) computing ballistic solution. Afterdetection,thecontactmustbe Detecting a submarine is no easy matter. tracked. Aboard a submarine,a graphic display Neither isit a simple task, once a submarine of target bearingsis made during this phase. contact is established, to carry out the successive From information furnished by this display, phases mentioned here. Although fire control targetmotionisestablished.Normally,the systems are capable of performing complicated submarine uses only passive sonar for tracking tasks,suchaspredictingfuturepositions, because active sonar may disclose thepresence submarine hunting is subject to errors caused by and even the location of the tracker. human judgment. Training in proper operation oftheequipmentformaximum ASW ShipboardSonarTechnicianstrackthe effectiveness is a must for Sonar Technicians. targetwithboth active and passive sonars, including LAMPS employing sonobuoys, and Because the same equipment often is used in depend lareely upon the strength and quality of detexting a submarine as in tracking it, detection the echo of the transmitted pulse for target is considered as a phase even though, in the information.An t isubma rineshipshavefire strictest sense,it may not be apart of the controlsystemsthatincorporateautomatic problem. tracking features. Once the contact is established firmly, the automatic devices keep thesonar on DETECTION PHASE the target and compute the course to be steered so that the ship will arrive at the best firing A submarine may be detectedinseveral position for the weapons selected foruse. ways, the most positive being visual sighting. If the submarine is seen to dive, classification is Basically, establishment of relative rates of evident; there is no question about the positive target motionisallthat is desired from the nature of the contact. tracking phase of the problem. The tracking phasesetsupthepatternforthenext Detection also can be made by radar. If a phasetarget motion analysis.Itisfrom the radar contact suddenly disappears, there isa relativeratesthatactualtargetmotionis good chance that the echo was the return froma determined.

113 INTRODUCTION TO SONAR

TARGET MOTION The attacking submarine may use different ANALYSIS PHASE methods to determine true direction of target motion. One method is by direct observation, Thetargetmotionanalysisphaseisa when mrsible, of the angles on the bow. Angle dynamic problem because both the attacking on the bow was discussed in chapter 5. unitandthetargetusuallyareinmotion continuously, and n11 relatedfactors change BALLISTIC SOLUTION PHASE constantly. As aresult of the target motion analysis phase, we can establish the true motion Itisdifficultto say when one phase of components of the target (course and speed). solving a fire control problem ends and another There are several ways of arriving at a course and begins.One phase usually overlaps another; speed solution. often they are concurrent. The start of the The target's true course and speed can be ballistic solution phase, for example, practically established on the NC-2 plotter maintained in coincides with that of the tracking phase. An CIC by Operations Specialists from information antiaircraft fire control system presently in use supplied by automatic inputs from sonar. The provides a solution in only 2 seconds once the NC-2 utilizes own ship's course and speed inputs targetis acquired by radar. Yet, during that to cause a lighted "bug" to follow own ship's time,thetargetistracked,itsmotion is movements. Sonar target true bearing and range analyzed, and the ballistic solution is computed. input cause a different colored "bug" to move Most underwater fire control systems, however, tothe indicated position. Target course and take longer to develop a solution. The reason is speed are then determined by the NC-2 plotter. that certain inaccuracies in target information The NC-2 plot aids the CIC officer in conning are inherent in underwater sound. Additionally, the ship. when CIC has ccntrol of the attack, range limitations of the weapons require the and supplies search arcs to the sonar operators attacking unic to be within a specific distance to whenever contact is lost. launchnontrainableweapons, and withina The target's true course and speed can also specific area to fire its trainable weapons. beestablished onthe dead-reckoning tracer After determining the target's course, speed, (DRT) plot maintained in CIC by OSs from andestimateddepth,twoitemsmustbe information suppliedby the sonar operators considered to complete the problem. One is over sound-poweredtelephonecircuits.The whether or not we need to close the target. The DRT utilizes own ship's course and speed inputs other is when to fire. to cause a lighted "bug" to follow own ship's If the target needs to be closed, keep in movements.Sonartargetrangesandtrue mind that you don't want to alert the submarine bearingsareplottedfromthebug,thus if at all possible. Also remember that the farther establishing the submarine's position. Course you stay away from an enemy submarine, the and speed are then determined by the DRT less chance he has to shoot at you. plotter. The second considerationwhen to fireis a Target true course and speed also can be decision made by the commanding officer after read from dials on the attack console. the fire control computer has reached a solution. On the surface ships the underwater fire Many factors are included in the FCS solution. control systems usually haveto compute a Due totheclassificationof many of these horizontal sonar range from the measured slant factors, they are not discussed in this manual. ranee and estimated target depth information. More detailed information may be found in STS This computation is necessary Y.ecause the fire 3 & 2, NET 10132-C, and STG 3 & 2, NET control system solves for target course and speed 10131-D. in the horizontal plane on the surfact in which the ship operates. Slant range is transmitted to DESTRUCTION PHASE theattackconsole from the sonar console. Depthissetmanually into thefirecontrol Destruction of the target is the ultimate goal system. of the submarine hunter. During this phase the

114 119 Chapter 7BASIC FIRE CONTROL

computed ballistic solution is used so that the ordnance may effectively be fired on the target. Although the surface ship's primary A/Sweapon isthe homing torpedo, whether fired froma tube or ASROC, the methods of submarine destructionbysurfaceshipsare many and varied.Included are ramming, hull-rupturing, near misses by torpedoes, complete destruction by atomic depth charge, or any action which forces the submarine to the surface where itcan be sunk by surface gunfire. Submarines, of course,usetheirA/Storpedoesontheir submarinetargets.Inshort,thedestructive phaseincludesactiononthepartofthe attacking unit that leads to a killdirectlyor indirectly. 71.123 FUNDAMENTAL PROBLEM Figure 7-3.Reference planes. The fundamental problem of fire control is to deliver fire on the selected target. A direct hit projectile hits th,.! target. The samegun, if fired is not required with some weapons. An atomic at a time other than when the deck is level, will depthcharge,for example,cancausethe miss the target. If the gun is free to train (rotate) destructionofa submarineifthecharge andelevate,however, compensation canbe explodes close enough to it. All attacks are made macie for the ship's roll and pitch. The gun then with the intention of hitting the target but, with will remain reasonably steady, thus improving some weapons, a near-miss is good enough. the chances of hitting the target, regardless of Solving the fundamental problem is no easy the ship's motion. A fire control system, in mattir. The difficulty is due to such factors as conjunction with a stable element, attempts to tainet speed, maneuvers, and range and speed of make the necessary adjustments to keep the th e. weapon, all of which play important roles in weapon steady. deliveringfireontheselectedtarget.The Deviationsfromthelevelattitudeare solution to the problem varies greatly with given measuredbya gyromechanism(thestable situations. A duck hunter, for example, "leads" element), which transmits to a computer in the the duck along the path of flight. If the hunter fire control system signals that indicate variation aimed directly at the duck as he fired, the shot of the position of the deck with respectto the would pass through the area at which he aimed: horizontal. but, because the duck is moving, itno longer Based on signals from the stable element, the would be at that spot when the shot reached fire control system computes values of train and there.Consequently,thehunter makes an elevationfortheweaponslaunchersto estimate of the future position of the duck, aims compensatefordeviationfromthelevel for that spot, and fires his gun. If he estimates attitude. The various attitudesare measured correctly, both the shot and the duck will arrive with reference to flat, two-dimensional surfaces simultaneously at the predicted position. The called planes. (See fig. 7-3.) An underwater fire firecontrol problemissimilar to the duck controlsystemcomputessolutionsinthe hunter's problem but on a much larger scale. horizontal, deck, and vertical planes.

REFERENCE PLANES Horizontal Plane Assume that a gun, rigidly fixed to a ship's A horizontal plane is tangent to the surface deck,fires,while the deck islevel, and its of the Earth. Visualize this condition by layinga 1 2 11 5 INTRODUCTION TO SONAR

playing card or an orange. The card represents of the basic system is provided so that you may the horizontal plane: the orange symbolizes the better understand the meaning and purpose of Earth: and the point of contact between the two the fire control quantities and their symbols. is the point of tanEtency. Every plane parallel to Ordnance pamphlet OP 1700 has established thehorizontal planeislikewise ahorizontal andstandardizedthenomenclature usedin plane. describingfirecontrolproblemsandtheir solutions for the control of guns, underwater Deck Plane weapons, and missiles. Volume 1 contains the nomenclaturefor the quantities applicable to The deck plane represents the level of the solutionsofthegunfirecontrolproblem. ship's gun mounts. (References to guns include Volume 2 coversthenomenclaturefor similar weapons systems.) When the ship is level, underwater related quantities. Volume 3 has the the horizontal and deck planes coincide: but, standardnomenclature formissilerelated when the ship rolls and pitches, the deck plane quantities. deviates from the horizontal. The stable element The geometrical quantities used in naval fire measures the amount of angular deviation and controlarethosequantities involved inthe transmits the information to the fire control mathematical solution of the general fire control system. The fire control computer compensates problem. Hence, the geometrical quantities fall for deck tilt by computing a solution in the into certain main classes of quantities. Each of horizontal plane, then makes train and elevation the main classes of quantities is represented by a corrections. In effect, the system brings the deck classname.Ineach class, other geometrical plane back to the horizontal. quantities,besidesthebasicquantity,are expressed by applying modifiers to the basic quantity. The modifiers expressthe way in Vertical Plane which the quantity is measured. Toillustrate,aclassof quantitiesfor A verticalplaneisperpendicular to the expressingpresenttargetpositionislinear horizontal plane and is the reference from which distance between own ship and the target. This bearings aremeasured.Relativebearing,for class of quantities is called ranges. The basic example,ismeasured in the horizontal plane geometrical quantity inthis class is the linear clockwise from the vertical plane through own distancebetween own ship and thetarget, ship's centerlirito the vertical plane through measured along the line of sight. It is expressed the line of sight. by the capital letter R. Another quantity in this The system of planes makes possible the class is the linear distance between own ship and designandconstructionof mechanical and the target, measured in the deck plane. This electronic equipment to solve the fire control quantity is symbolized by applying the modifier problem. These lines and planes are imalMlary d (meaning measured in the deck plane) to the extensions of some characteristic of the ship or basic range quantity R, forming quantity Rd. target. The nomenclature assigned to represent the basic geometrical quantity in each class and the letters and numerals used as modifiers are listed FIRE CONTROL NOMENCLATURE (as mentioned previously) in the three volumes of OP 1700. Extracts of Volume 2 of OP 1700 Fire control nomenclature provides a brief (Underwater FireControl Nomenclature) are and accurate means of expressing quantities that contained inSonar Technician G 3 & 2. otherwise would require extended descriptions. Although all underwater fire control systems use SONAR POSITION QUANTITIES basically the same fire control symbols, each system has a few symbols that are unique. The When a target echo is received by a sonar entire nomenclature is too lengthy and detailed transducer,thetarget actuallyisnot atthe for inclusion in this text, but a brief explanation positionindicated on the sonarscope but at

116 Chapter 7 BASIC FIRE CONTROL some other location. This difference in target Two class quantities. range (R) and bearing positions is due to curvature of the sound beam (B),are shown, togeth,.1- with the modifiers and totarget movement durina echo return necessarytoexpresstheappropriate time. measurement. Quantitiesrelatedto apparent The determination of actual target position target position are represented by the lowercase requires the application of corrections to the letter a: those related to past target position use sonar measurements. These corrections. whiLli theletterp.Themodifierh rn,..sans the are computed inthe underwater tire control measurementisinthe horizontal plane: the system,consistof twopositionquantities: modifier v refers to the vertical plane. apparent tamet position and past target position. (Target course and speed are basicali: produced Apparent Target Position by this information.) Sonar position quantities Apparent target position is the point from are illustrated in figure 7-4. which the sonar echo appears to come. It differs

r'7

PRESENT TARGET POSITION

TARGET TRAVEL DuRiNG TIME OF SOUND PuLSE TRAVEL FROM TARGET TO SHIp PAST TARGET !Rya/SouND BEAM \ I POSITION APPARENT TARGET PosiTION

71.124 Figure 1-4 . Sonar position quantities.

1 17 i2 INTRODUCTION TO SONAR

frompresenttargetpositionbecauseof Target depth (Rvua) and slant range (Ra) are refraction of the sound beam and because of combined to give horizontal range to past target target travel during the time required for the position (Rhp). Raiscomputed with other echo to return to own ship. The dotted lines in quantities to give present target position (c(Ra) figure7-4representapparentposition for use in the weapons system. measurements. The quantity Baisapparent targetrelativebearing, and Rha is apparent target range measured in the horizontal plane. EQUIPMENT An underwater fire control system usually is Past Target Position designed to operate with a particular weapon system although efforts are made to make the Past target positionisthe location of the system compatible with future weapons. One target when struck by the sound beam. In other modern fire control system may be used with words, itis the position from which the sonar several weapon types. Regardless of the system, echo actually comes. Past target position differs it serves only one purpose: the destruction of fromapparenttargetpositionbecauseof enemy submarines. refraction of the sound beam. It differs from After target position is determined, the basic presenttargetpositionbecauseoftarget problem for the systemisto predict future movement during the timeittakes the sound targetposition, calculate the required attack pulse to return to own ship. course and firing time, and transmit the data to weapons and control stations. Present Target Position Because most underwater FCSs are of a classified nature, they cannot be included in this Present target positionis where the target text. Certain concepts are discussed, however, to actually is located when the sonar echo reaches give you some basic knowledge of how a FCS own ship. It represents the distance traveled by operates. the target during the timeittakes the sound pulse to return to own ship from the target. As Electromechanical Devices shown in figure 7-4, quantity B is the target's relative bearing at the time the echo is received. Electromechanicaldevicescombinetwo d i fie re n ttypesofactionelectricaland

BUSHING

HOUSING RETAINING RING

ELECTROMAGNET FRICTION PLATE ELECTROMAGNET ASSEMBLY SHIM WASHER BEARING RETAINING RING BUSHING CAP ASSEMBLY ---- HOUSING SPRING WASHER

\ SPRING WASHER SHIM WASHER SHAFT sd S'HAFT o

71.60 Figure 7-5.Magnetic brakeexploded view. Magnetic clutchexploded view. 12 Chapter 7BASIC FIRE CONTROL

mechanical. These devices, such as the magnetic a schematic. Figure 7-7 shows the schematic brake and magnetic clutch, have wideusage and symbol of an electrical resolver. applicationinfirecontrolcomputing When the resolver is zeroed electrically, the componen ts. rotor coil clamped to the stator coil is called the cosine coil. The other rotor coil, at right angles The magnetic brake can stop and holda to it, is calied the sine coil. As the rotor rotates shaft at a given value when certain conditions from 0° to 3600, the voltage inducedacross the are met. The magnetic brake is used to prevent a cosine coil follows the cosine function of the line of gearing from turning. When the current is excitation voltage. Similarly, the voltage induced off, no magnetic action takes place. In figure across the sine coil follows the sine function of 7-5, (an exploded view of a magnetic brake), the excitation voltage. notice that the spring washer holds thecap away from the electromagnet, thus allowing the shaft to turn freely. When the current is turnedon, SCHEMATIC IDENTIFICATION the electromagnet exerts a force great enoughto OF SYSTEM COMPONENTS overcome the effect of the spring washer and pulls the cap tight against the electromagnet, Inthe maintenance publicationsforfire thereby locking the shaft in place. control systems, the devices described in this section are identified by standardized symbols. An electromagnetic clutch is used toengage The identifying symbols and their abbreviations and disengage a line of gearing. An exploded for system components are reproduced in figure view of a magnetic clutch is shown in figure 7-6. 7-8. Usa;o ofme of the component symbols in When current is fed to the electromagnet, the a sectiorH ,!i,q:7-am may be seen in figure 7-9. friction plate assembly andcap assembly are in contact with each other, and the output line UNDERWATER FIRE transmits input rotation. When current to the CONTROL SYSTEMS electromagnetiscutoff,thefrictionplate assembly and cap assembly separate by spring A modern fire control system is tailoredto action,losing contact with each other. The the requirements of a particular output line does not rotate or transmit weapon system. any Aboard submarines, the weaponiseithera input to the clutch when thesecomponents are torpedo or the SUBROC. Aboard surface ships, separated. the weapon is either a torpedoor the ASROC. Regardless of the type of FCS used, eachone Electrical Resolver has the same purposeto direct theweapon to the target. Another device that should be considered here (although itis an electrical assemblynot STATOR electromechanical) is the electrical resolver. The COIL resolverisa computing device and functions much likeatransformer.Itiscapable of separating an electrical input vector intotwo EXCITATION E E cos 0 right angle components. The resolver hasa stator and a rotor, each part consisting of two separate coils wound atrightangles to eachother. ROTOR Voltagesinducedonthestatorcoilsby COILS excitation of the rotor coils dependupon the E sin 0 displacement of the rotor with respect to the electrical zero reference axis of the resolver. In solving for a single vector, only one of the stator 12.105 coils is connected electrically and representedon Figure 7-7.Electrical resolverschematic symbol. INTRODUCTION TO SONAR

COS COSINE MECHAN,m .R. IPA MECHANICAL INTEGRATOR CO CAM MECHANICAL Cam MC HANDCRANK OR KNOB

StN SINE MECHAN,SM D GEAR DIFFERENTIAL OF FRICTION DRP.E FRICTION TO FRAME

CAM NECHANICAL CAN f OACTION GENERATING) LJL LEVER MULTIPLIER uto St. Lima STOP C7:3 -LD St..ErRACTNE LEVER ADDatvE LEvER OL LINEAR OVERRIDE 0*.,-RENTiAL C:=3 Fl- r+1 ° DIFFERENT,AL fm:di c MECHANICALCOUNT E R MECHANICAL COMPUTING SYMBOLS (5) OR ROTARY OVERDRIVE 0 DL DIAL ELECTRICAL CONNECTION MS SERVOMOTOR (IN A MECHANICAL SCHEMATICI (0.0, V VACUUM TUBE DL DIAL GROUP MECHANICAL CONNECTION R RESISHOR

-r F FUSE MECHANICAL NONCOMPUTING SYMBOLS H THTHITE RESISTOR r-L,) L LAMP

THERMAL SWYCH Sw Hi C 1,APUCIT0R L INDICATOR LAMP CE MAGNETIC CLUTCH OR MAGNETIC BRAKE Sw mICROSwITCH C 'L'eN.T.HRO CaPAC.TGH

A AMPLIFIER

T TIME MOTOR ROTART SviiTCH

.0 REC T1FIER SO SYNCHRO DIFFERENTIAL mCFOR RH RHEOSTAT -SOG SINCHRO DIFFERENTIAL TRANSMITTER 5 SERVOMOTOR T THANSFoRmiR If01).` SC T 50501150 CONTROL TRANSFORMER SCT SYNCHRO CONTROL rgrp_t_i TRANSFORMER rqm-, SW MICROSWITCH

MECHANICAL CONNECTION IN AN ELECTRICAL SCHEMATIC) SM SINCHRO MOTTR SW CAM-ACTUATED OP DAMPING REACTOR -C> MICROSvoTCH SG SYNCHRO TRANSMITTER ELECTRICAL CONNECTION

ELECTRICAL SYMBOLS ELECTROMECHANICAL SYMBOLS

13.5 Figure 7-8.Identifying symbols and their abbreviations.

Surface Ship System A detailed discussion of the complete Mk 114 UBFCS is contained in Sonar Technician G 3 & 2, A shipboard underwater fire control system NET 10131-D. It is recommended that you refer (the Mk 114 UBFCS) isillustrated in figure to the STG publication after completing this 7-10.Thesystemperformsthefollowing manual. functions: Submarine System I.Integratesassociatedfire control equipment with own ship's components. When a submarine is on the surface, the fire 2.Receivestargetpositioninformation control problemisessentiallythe same as a from sonar or radar and combines it with own surface ship's. However, when the submarine is ship's and ballistic's data to produce weapon below the surfacethetirecontrol problem orders. becomes much more complicated. Figure 7-11 3.Providesaidedtrackingand shows a representative submarine fire control position-keeping information back to the sonar. t_!ni (the Mk 113 FCS). 1 2 5 1 ?0 Chapter 7BASIC FIRE CONTROL

B4 d(Rm)

HIGH SPEED

HIGHSPEED

By5 LOW.SPEED Rh5 d(Rm) d(Bmy))

LOW.SPEED VERY-LOW- I SPEED l'' I d(Brny) I I CROSSOVER !CROSSOVER d(Rm) = IR/15 I AMPLIFIER AMPLIFIER k_ RATIOf_ GEAR MG1 1

MG1

Rh5 d(Rm) SIN d(Bmy)= d(Rmx) d(Rm)COSd(Bmy)=d(Rmx)

R3 IR2

d(Rm) SIN d(Bmy)=d(Rms) d(Rm) SINE.COSINE d(Rm)COSd(Bmy)=d(Rmy)

Rh5SINd(Bmy)=Rh5x PRESET AT 60,000 YARDS

1

1 Rh5SERVO MODULE .-1 L...... dOmy) SERvO MODULE I

71.131 Figure 7-9.Rhs and d(Bmy) schematic diagram relay transmitter Mk44. INTRODUCTION TO SONAR

PERMISSION TO FIRE POSITION INDICATOR ATTACK MK 78 t PAYLOAD SELECTED, READY INDICATION, CONSOLE MISSILE OR WATER ENTRY POINT RANGE ANDBEARING. MK 53 TARGET RANGE, BEARING, AND ANGLE, ANDLAUNCHER TRAIN ORDER

MISSILE AND RAIL SELECTION ORDERS; MISSILE VELOCITY, TIME TO SEPARATION. AND TORPEDO SETTINGS, STABILIZED LAUNCHER TRAIN AND ELEVATION ORDERS, AND LAUNCHER STANDBY AND FIRE ORDERS CAPTAIN'S CONTROL PANEL MK 199 LAUNCHER AND MISSILE INTERLOCKS AND INDICATIONS

ASROC MISSILE LAUNCHER LAUNCHER AND MISSILE INTERLOCKS AND INLICATIONS AND MISSILE SIMULATOR MK 6 MISSILE AND RAIL SELECTION CRDERS; TORPEDO SETTINGS; STABILIZED LAUNCHER TRAIN AND ELEVATION ORDERS; AND STANDB, AND FIRE ORDERS MISSILE VELOCITY AND TIME TO SEPARATION LAUNCHER SETTINGS MK 112

MISSILE VELOCITY AND TIME TO SEPARATION SETTINGS RELAY TRANSMITTER UK 43 ISA CHECKS

71.132 Figure 7-10.Mk 114 underwater ballistics fire control system.

The Mk 113 FCS provides solutions for frequentoperationof a systemexercises launchinathe SUBROCmissileandmany servosystems,powerdrives,and computing differentmodsoftorpedoes.Duetothe networks, therebybringing attentionto any classificationof thissubject,itwill not be existing trouble. discussed any further in this manual: the Mk 113 Transmission Tests FCS is discussed in detail inSonar Technician S' 3 & 2.NET I 0132-C. Transmission tests are held to cheek the accuracy of automatically controlled devices at FIRE CONTROL SYSTEM TESTS remote stations and to check their response to Certain transmission. computing, and rate changing signals. When running these tests, the tests must be performed to ascertain that the first step is to establish voice communications fire control solution is correct and that values betweenstations.Next,theman atthe arc received correctly at remote stations. Also, transmitting station must read the exact output

122 127 MISSILE HEATER CONTROLLER MN 24 MOO 0 (4) ;$ ',,,777777n77. 113' WEAPON MONITOR FANEL MK 19 MOD 0 A RECKONINGANALYZER DE AD MAGNETICELECTRO. LOG GYRO COMPASS MX 19 MOD! 41.41Tri 7171V riNr!" - , LEVELING MK 129 MOOD --_ SENSACMK158 ELEMENT 000 0 121 AMPLIFIER ATTACK DIRECTOR MK 75 MOOD ANALYZER CONSOLE MK 51 M000 CABINETSPARES P&SSArt 13:1 FIRE CONTROL SWITGIBOARD q5C0 \ ATTACK CONTROL MOLE MX SO MOO 0 ATTACK CONSOLE STABILIZATION CONTROL. UNIT MK 83 MOD 0 (3) .:PAJNAC AN/BOO-ISYSTEMSONAR SINS PUFFS DIGITAL COMPUTER MX130 MOD 0 MX 140 MOD 0AMPLIFIER PER;SCORE . . . . RADAR AND SPECIAL FLEET TEST A ND :ID II ION111,' : - , J EOUIPMENTIFSTACOE1 OUT ' ANALOG AMPLIFIER TEST SET SUPPLY TESTANALOG SET POWER CONVERTER ZEROINGDEVICE ALIGNMENTRESOLVER DEVICE TEST SE T REL AY 144\MZE1111 EiMUL ATOP Figure 7-11.Mk 113 fire control system. MK 402 MOD 0 - AIX 404 MOD 0 MX ! MOD 0 MX 1 MOD 0 MK 403 MOD u MK 10 MI.: u 141.173 INTRODUCTION TO SONAR value of the quantity being checked. In turn, the STATIC TESTSStatic testscheckthe man atthe receiving station must adjust the overall operation of the computing system in a receiver to correspond to the reading from the standstillcondition.Inthistypeoftest, transmitting station. appropriate testvalues are inserted manually, and the problem is stopped at a fixed point. Input test quantities are thus of a constant value Computing Tests and produce fixed answers which do not change with time. These fixed answers indicate whether As sonar tracks a moving target, constantly the static portion of the fire control equipment changinginputsarefedtothecomputer. is performing properly. Instantaneous values of these inputs are used by the computer to solve ballistic computations and DYNAMIC TESTS.Dynamic tests are run predict future target positions. The computer's to check the computer's generation of bearing solutionis,therefore,based on aninfinite and range for specified time intervals against a number of static(still)problems. As relative mathematical solution whose answer contains motionratesareintegratedwithtimeto correct amounts of change in quantities for like generate computer changes in target position, conditions. During thetest.fixed values are the problem becomes dynamic. To test the assigned to relative motion rates by manually computer's accuracy, consequently, both static setting inputs to the relative motion group. The and dynamic tests are run. time system of the computer is then moved,

TARGET

Bts305° WATER ENTRY c0)21, POINT \ts \O / \O

\,.., TARGET ANGLE \,.5> \ LINE OF SOUND (BMISSLEI EARING N00 \ Elfs

\\ 5_1 o 1001 TARGET RANGE Ra OWN c ( B 5) r- 313 ° SHIP

C.9 71.133 Figure 7-12.Missile and target dial and counter functions.

124 Chapter 7BASIC FIRE CONTROL

eithermanually or bythetime motor, an amount equal to the test interval. Readings are then taken to ensure correctness of the solution,

Rate Tests Bdg LAUNCHER LINE OF SOUND TRAIN ORDER DIAL Rate control tests check the functioning of therate control system. Mechanisms of this \AILINSION, system correct values, such as target angle and target speed, so that computer target motion rates agree with actual rates of the target. In otherwords,thistestdt termines the time required for the computer to arrive at correct relative motion rates. Time required must be small, but smoothness of tracking must also be considered.Theratecontrolsystemisa compromise between these two factors. Rate controltestsconsist of tracking a hy pot he t icalmotionlesstargetwiththe computer set for a selected sensitivity of rate _111 error detection. Sensitivity is controlled by the Bya late ,Ba time constant input to the rate control system. APPARENT APPARENT TRUE TARGET RELATIVE Initially a large error is introduced and the time BEARING DIAL TARGET motor is started. Time required to reduce the BEARING DIAL

error by a preselected percentage is timed by a TARGET stopwatch. This stopwatch reading is a measure of the actual time constant or sensitivity of the system.Itis compared against the theoretical value for the test. LINE OF Each fire control system is provided with a SOUND set of tests to determine the operating accuracy. Some are daily tests, some are weekly tests, and some are monthly tests. Refer to the specific 01) or OP for each individual fire control system test, 340° INTERPRETING DIAL READINGS Co:355° Sonar Technicians must be able to interpret and sometimes interpolate sonar and fire control equipment dial settings. Information to be read from these dials includes such values as range, target angle, true bearing, relative bearing, and many other fire control values. Normally two types of dials are used: disc dials and ring dials. A disc dialis simply aflat, circular plate secured to a shaft and inscribed with values of t hefunctionitserves. Aringdial is circular-shaped also, but has a hollow center to permit placing a disc dial within it. An example 71.134 of the use of these dials is shown in figure 7-12. Figure 7-13.Own ship dial group functions.

125 130 INTRODUCTION TO SONAR

The dial group on the telt shows the relative also indicates whether the selected weapon will water entry point bearing c(B5) of an ASROC clear the superstructure when lired. missile. The dial is read on the inner dial against The outer dialof own ship's dial group the line index on the missile of the outer dial. displays apparent true target bearing Bya values The c(B.5) shown in this case is approximately when read with referenceto the LINE OF 313°. SOUND index. The outer dial is graduated in 5° The dial on the right shows the target angle increments and is numbered in 30° increments (Bts) of the target being tracked. Target angle is lrom0°to360°. Own ship'scourse(not read against the line or sound index. The Bts received as an input) can be interpreted by the shown in this case is 305°. position of the bow or own ship inscribed on the Figure 7-13 shows the more complex own inner dial against the graduations on the outer ship'sdial goup. This group includes three dial. This interpretation is possible because the concentrically mounted dials: an inner dial, an equation for Co is: Co = Bya Ba. The Co intermediate dial, and an outer dial. The inner value shown in figure 7-13 is 355°. dial displays apparent relative target beaiing Ba The dials just discussed are only a few of the when read with relerencetothe LINE OF many that you must be able to interpret. Of SOUND index. The inner dial is gaduated in 5° particularimportance is theabilityto increments and is numbered in 30') increments interpolate (to "read between the lines-) and to from 0° to 360°. The Ba value is 3450 .Areas note direction of change of dial readings. Our indicatingbearingswhereownship discussion of the fire control problem, and of superstructure 1Nould interfere with missile firing the equipment used to solve the problem, was are indicated on the inner dial as UNSAFE. Own necessarilyrestrictedtolundamentals. ship's outline is also inscribed on the inner dial. Co m put ermechanismslirecontrol The intermediate dial of own ship's dial nomenclature, and antisubmarine weapons were goup contains a diamond index which indicates only briefly covered, serving to acquaint you launchertrainorder Bdgvalues when read with the problems involved in making attacks on against the inner dial. The Bdg value is 310°. enemy submarines. You need to study many The Bdg index, when read with reference to the technical manuals and other training courses to inner dial, indicates launcher train order with fullycomprehendthedutiesofa Sonar respect to own ship's bow. The intermediate dial Technician.

126 CHAPTER 8

COMMUNICATIONS

Theessentialfactor incommunication bridge level, or in some other section of the ship between two persons is that the language they (depending on the type and class of ship). use be understandable to both. Not only must Becauseitis remote from the bridge, sonic one person be able to express himself clearly, means of communication must be established buttheotherpersonmustbeableto between thebridge and sonar control. This comprehend what is communicated. requisiteis accomplished by utilizing oneor Realizingthatmanyproblems are more of the internal communication systems. encountered in communications, the Navy has Shipboard circuits include MC (loudspeakers) adopted standard methods and practicesto circuits, sound-powered phones, and automatic minimizeerrorsandmisunderstandingsin devices. These devices are remote indicators and message transmittal and reception. Many of are usedtotransmitbearingandrange these standard procedures are used by other information, weapon status, and many other allied services. They are invaluable in conducting types of data needed by other stations. jointinternationaloperations. The phonetic When sonar contactis made, the bridge alphabet has been adopted by all allied forces usually is informed over an MC system. By this for combined operations. method, all stations concerned are alerted, and In this chapter you will become acquainted sound-powered phonesare then manned to withsomeoftheinternalandexternal eliminate excessive noise levels caused by the communicationsystemsusedaboardship. constant use of loudspeakers. The ASW officer is Additionally, you will learn correct operating directed to make the attack. Although most of procedures for radiotelephone and underwater theinformationflowisconducted on the tele phone communications. Because the sound-poweredphones,theinformationis phonetic alphabet and sound-powered (S/P) backed upbyautomaticelectromechanical telephoneproceduresarecoveredinBasic devices so all stations are awaue of theprogress MilitaryRequironents, NAVEDTRA 10054. of the attack. they are not included in this text.

SOUND-POWERED PHONES INTERNAL COMMUNICATIONS The shipboard voice communication system Most Navy personnel, regardless of rate,are used most extensivelyisthe S/P telephone familiar with internal communications. Sonar network. It consists of primary battle circuits JA Technicians,especially, have occasion to use to JZ, with auxiliary and supplemental circuits severalty pesofsystemsavailablefor for useif a primary circuitis damaged. The transmitting sonar information.Itisalmost degree to which these circuits are manned varies. impossibletoconductattacksonenemy Few circuits are used under normal peacetime submarines or ships without some method of cruisingconditions.During generalquarters, internal communications. On a destroyer,sonar when all battle stations are manned, all circuits control may be located below decks, on the may be used.

127 132 INTRODUCTION TO SONAR

Of primaiy concern to the Sonar Technician Anothercommunicationsystemfound are the JA, JP, and .IS circuits. The JA, the aboard most ships and submarines is the 21MC captain's battle circuit, is used for transmitting (captain's command system).Itisa two-way orderstokeycontrolstationsandfor system,witheachintercommunicatingunit exchanging vital information with those stations. capable of calling either10 or 20 stations, Weapons control information is passed over the depending on the type of ship in which itis 8JP circuit. The other S/P circuit you will installed.Theessentialcomponentsare a probably man is the 61.1S. It normally is used as reproducer, amplifier, and controls necessary for a one-way system to provide contact range and operation. The reproducer acts as a microphone bearing and other data to UB plot, CIC, and the in the calling unit and as a loudspeaker in the bridge.The 1J S circuit is themain unitcalled. Amplification takes place inthe antisubmarine attack team control circuit.It calling unit. The controls consist of the talk connects the bridge, CIC, and sonar control, and switch, pushlnitton assembly, busylight, call is used primarily for conning orders when sonar light,volume and dimmer controls,anda or CIC has control of an attack. Normally, the microphone or handset jackbox. 1JSis manned by officers in charge of the Tooperate the 2IMC, depress the various stations. pushbutton of the station desired. If the station Circuit discipline must be maintained at all is busy, the red BUSY lightwill flash. If the times when you are wearing phones. Personal BUSY light does not flash, depress the TALK conversations with friends on the same circuit switch and speak directly into the speaker grill. may cause a delay in the transmission of vital Release the TALK switch to listen. When your information, resulting ina delayed or missed conversationis completed, depress the release attack.Withthehighspeedsofmodern button at the far left end of the row of' station submarines, such a delay could result in the loss buttons to remove your intercom unit from the of your ship or the ship you aretrying to circuit. When you are called, the CALL light protect. illuminates.Itisunnecessary to depress the button of the station calling: merely use the TALK switch as described herein. MC SYSTEMS Despite its many advantages, when the MC systemisused,thenoiselevelisincreased Although sound-powered phones arethe greatly. This condition occurs because of its most commonmeansofinternal speaker-type output and the fact that it picks up communications, there are other methods, one background noise from the transmitting station. of whichisthe MC (shipboard announcing) Because of the high noise level generated by system.TheMC systemisanelectronic operating the 21MC, itshould be used only speaker-typesystem,similarto an when absolutely necessary. office-to-office intercommunication system, and isdesignedto provideamplifiedvoice REMOTE INDICATORS communication. Sonar and CIC underway watch stations T h e fastestmeansofcommunicating usuallyarenotfully manned under normal information is to transfer it electrically. Through cruismg conditions aboard ASW ships. When a theuse of electromechanical and electronic sonar contact is gained, the 29MC (sonar control repeaters,sonarinformationisdisplayedat and information) is used to alert CIC, UB plot, remote locations aboard ships and submarines and the bridge. Contact information (such as without delay. ranges, bearings, and doppler reports) is passed Onety peofdisplay, an electronic over this circuit until the contact is classified as azimuth-rangeindicator,showsbearing and nonsubmarine or until ASW stations can be fully range ot' a contact on a cathode ray tube. It manned. Submarines utilizethe 27MC (sonar duplicates audio and video information present and radar control) system. at the sonar operator's console.

128 133 Chapter 8 COMMUNICATIONS

Another type of remote indicator displays In antisubmarine operations, voice radio is sonar information electromechanically. Contact usedtoexchangecontactand tactical range and bearing are shown by counters similar information het \Veen the CICs and bridges ofthe to an automobile's mileage indicator. Thereare ships participatir,g in the operation. The eaptain many other electromechanical transmitters used or the 001) mans the bridge radio circuit, used todisplaysonarinformation. 'The most primarily to exchange tactical iniormation. The commonly used are the Mk 78 position indicator CIC oilicer and the Operation Specialist handle and the Mk 44 relay transmitter usedwith the the combat information (('I) net to exchange ASROC weapon system. con t actin form at ionbet weenCICs.Contact As youcan see,electrical/eieetronic information between (lc'sis evaluated by tile repeaters reduce the time required to transmit CIC evaluator, andpertinentinformationis information,eliminatenoise-producing relayed to the captain and 001)on the bridge transnnssions, and reduce the volume of traffic by use of sound-powered phones. over S/I' telephone circuits. Because radiotelephone proceduresare used withthe underwater telephone andbecause Sonar Technicians may be assigned CIC watches EXTERNAL COMMUNICATIONS during normal cruising conditions, it isnecessary fory ou tobe fa IIIliarwithproper During antisubmarine operations (and, lor radiotelephone procedures. that matter, all operations, itis iinperative that conmumications between ASW units, suchas RADIOTELEPHONE PROCEDURES ships and aircraft, be conducted smoothly and efficiently, and he free of coniusion insofaras When you use a radiotelephone,your speech practicable. If a faulty microphone switch of a must be clear and slow. Speak themessage by sound-powered phone frequently cuts out, this naturalphrasesnotinstilted, word-IV-word common failure can prevent vital information fashion. Use a normaltone:don'tshout. from getting through just as effectivelyas it" it Pronounce word clearly and distinctly. were not reported at all. pausing at intervals. Think about whatyou are Poorly trained or.naen..Ve operators can going to say, then say it. Keep themessage as cause confusion, delay, and mistakes, and may brief as possible. even create a dangerous situation. Heading RADIOTELEPHONE The basicformat oi amilitarymessage Radiotelephone VD, commonlycalled consists of the heading, text. and ending. The voiceradio,isa rapid means or exchanging messageform is inplaindress,abbreviated informationbetweenships,aircraft,and plaindress, or codress. Codress isan encrypted submarines. Voice radio usuallyis amplitude message,withwhich aSonarTechnician modulated. A continuous-wave radiofrequency normally is not concerned. Plaindress is used for carrier has an audio signal impressed upon it, radiotelegraph and teletype communications.as varying its amplitude in accordance with the well as forradiotelephomeadministrative audiovariations. A handsetor a carbon messages. A plaindress message usually has a microphone is used to key the transmitter. complex heading, consisting of call. transmission instructions,precedence.date-timegroup. Although voice radioisafast means of address.andother elements. Thetypeof communication, speed without accuracy ismore radiotelephonemessage youwillusemost . than worthlessit can be dangerous. When ships however, is the abbreviated plaindress. in which are operating together athigh speeds and in the b iding includes only the station called and closeformation. amistakeor adelayin thestationcalling.Insome instances,;titer communications can cause a collision. communications areestablished,theheading

119 1 24- INTRODUCTION TO SONAR

contains only the station calling. An example of Ending a typical heading is: BR ASSPLATE --THIS IS ESKIMO. The ending or aradiotelephone message consists or one of two wordsOVER or OUT. Text When OVER is used, the :;ender is telling the receiver to go ahead and transmit, or "This is the The text of' the message is the basic thought end of my transmission to you and a response is or idea the originator wishes to comniunicate. It necessary." With the use or OUT, the sender in follows the heading, and is separated from it by effect is telling the receiver: "This is the end of the word BREAK. Quite often radiotelephone my transmissionto you and no responseis messages, particularly those of a tactical nature, required."Inmotionpictures and television are coded. There are several reasons for coding productions, youarelikelytoseemilitary messages. The first is obvious: so that the enemy personnel say "Over and out," hut there is never will not know your intentions. Ii, f'or instance, a need for their combined use in this manner. you were ordered in plain language to commence asonar listening sweep andthe CALL SIGNS message was intercepted by an enemy submarine, he could rig for silent running to reduce his noise output to a minimum, making In radiotelephone procedure, ships have call your job all the more difficult. If the message is signs that are common, easily pronounced words sent in code, however, chances of interpretation or expressions. The radiotelephone call sign of' by the enemy are reduced even though he one ship, for example, is BLUE STAR: another should intercept it. Another purpose is brevity. is BEANSTALK; still another is EL TORO. All The less time on the air, the better (for both U.S. Navy ships are assigned a voice call sign. If security and practical reasons). you need to know the voice call sign of any Navy ship, you can find it in the communication Signalcodes arecontained in communication publications known as signal publication JANAP 119. books (of which there are several), each having a particular application. One signal book consists PROWOR DS of two letters, or a combination of letters and numerals,thatusuallyareusedfortactical Radiotelephone procedure also requires the signals. (Members of NATO use this book, as use of standard procedural wordscalled wellasthe standardphonetic alphabet, for prowords.Although prowords arenot code combined operations.) As an example, a certain words as such, they say a geat deal with the two-letter and a numeral signal tells all ships to utmost brevity. The words OVER and OUT, make oil fog and smoke. From his signal book. mentioned earlier, are prowords. Besides OVER the captain of anItalian ship can read and and OUT, two other prowords that are never understand the meaning of the signal as quickly used together are ROGER and WILCO. ROGER as the captain of a U.S. Navy destroyer. Two is used as a receipt.It merely means that you lettersand a numeralthusovercomethe have received the messagenotthatyou language barrier and make a brief message as understanditorwillcarry out any orders well. contained init. WILCO isthe answer to the Another means of reducing transmission proword ACKNOWLEDGE and means that you time and providing adegee of securityis will comply with any instructions or orders throughtheuseofbrevity code words. In contained in the message. For this reason, the general, these code words are used to convey proword WILCO must never be used without contactandrelatedinformation. specific permission from a person having the Communications publication ACP 165 contains authority to grant such permission. This person the operational brevity code. is usually the commanding officer of your ship. At the end of the text, the word BREAK is Following isalistof the more common used again to separate the text from the ending. prowords, the meaning and usage of which you

130 135 Chapter 8COMMUNICATIONS

should memorize. This list is not as complete as Ersav_ad Mqaailig thelistsincommunication publications.lt consists mainly of the prowords you are most ROGER I have received your last likelytohear anduse on the underwater t ransmission telephone. Should you be interested in seeing a satisfactorily. more complete list of prowords, check NTP-4 or ACP 125. SAY AGAIN Repeat all (or portions Proworii Meaning indicated)ofyour message. ALL AFTER All after. THATIS You have repeated my ALL BEFORE .. . All before. CORRECT message or have given informationcorrectly. BREAK The textis separate at thispoint. Do not THIS IS This message is from. confusetheseparated portions. TIME What follows is the time or date-time group of CORRECTION. Anerrorinmy this message. transmissionhasbeen made. I now correct it. TO Thismessage is for DISREGARD This entire transmission actionbyand is THIS is in error. Disregard it. directed to TRANSMISSION WAIT I must pause ror a few FIGURES Figu resornumerals seconds. follow. WAIT OUT I must pause for longer FROM Thismessage is than a few seconds. originated by

WILCO I havereceivedand I SAY AGAIN I re peat theentire understoodyour transmission(or message, and you have portions indicated). theassuranceofthe command that it will be I SPELL I shallspell the next compliedwith.(This word with the standard type of answer requires phonetic alphabet. CO's permission.) OUT This is the end of my transmission. No receipt WORD AFTER . ... The word after (word) is required. (word) is

OVER Go aheadwithyour WORD BEFORE The word before (word) transmission atthis (word) is time. (Or, this is the end of my transmission for WRONG Your lasttransmission wnich a response is wasincorrect.The required.) i '3 6 correct version follows.

131 INTRODUCTION TO SONAR

INTERNATIONAL MORSE CODE Letter Pronunciation

The international Morse code is a telegraphic dit alphabet, which is another way of saying that it isa dot and dash communication system. The di-di-DAH-dit code is pronounced by saying "dit" and "dah," not "dot" and "dash," so forget about dots and dashes and think only in terms of dits and dahs. DAH-DAH-dit The group of dits and dahs representing each character must be made as one unit, with a clear di-di-di-dit break between each dit and dah, and a much more distinct break between character. di-dit

Never try to identify a character by counting J di-DAH-DAH-DAH dits and dahs. Don't let yourself get into this habit. It's a temptation at first, but you won't DAH-di-DAH be able to count fast enough when the code speed picks up. Learn sound patterns instead. To understand what this requirement means, rap di-DAH-di-dit out the pattern beginning "Shave and a haircut." You recopize this ditty from its characteristic DAH-DAH rhythm, not because it has a certain number of beats in it. You must learn code the same way. DAH-dit Each character hasits own distinctive sound pattern. With study and drill, you will learn to 0 DAH-DAH-DAII recognize each patternasfastas you now recognize "Shave and a haircut." The accent di-DAH-DAH-dit always falls or. dahs, and you should pronounce each rhythmical combination with that rule in DAH-DAH-di-DAH mind. Go through the alphabet several times to getthefeelof the sound of the dit-dah di-DAH-dit combinations. di-di-dit THE CODE DAH In the pronunciation guide for the sounds of thecharacters inthe accompanying list,the di-di-DAH sounds are written out phonetically insofar as possible. The short sound "dit" actually takes V di-di-di-DAH on the sound "di." The "i" is very short and the "t" is dropped. di-DAH-DAH

Letter Pronunciation X DAH-di-di-DAH

A di-DAH DAH-di-DAH-DAH

DAH-di-di-dit *Z DAH-DAH-di-dit

DAH-di-DAH-dit *ZULU is written as -Z- to avoid confusion with DAH-di-dit the number 2.

13? 137 Chapter 8COMMUNICATIONS

Number Pronunciation Short Sounds Practice Words

di-DAH-DAH-DAH-DAH T DAH MINE, TIME, MAINE, TEAM 2 di-di-DAH-DAH-DAH A di-DAH AIM, NITE, TAME, 3 di-di-di-DAH-DAH TEA, MATE

4 di-di-di-di-DAH I di-dit TAME, NAME, MITE, MIAMI 5 NI DAH-DAH MAMA, MEAN, MAN, 6 DAH-di-di-di-dit MAT. EMIT

7 DAH-DAH-di-di-dit N DAH-Dit MINT, MANE, TAN, ITEM, TINT 8 DAH-DAH-DAH-di-dit Medium Sounds Practice Words DAH-DAH-DAH-DAH-dit

**0 DAH-DAH-DAH-DAH-DAII- D DAH-di-dit MUST. SAME. MAMA, SUIT. AUTO

Study and Practice G DAH-DAH-dit MUSS. OUST, MUSE, MUTE, ATOM If you have any trouble learning code, the following method may be helpful. Go through K DAH-di-DAH TAUT. MASS. MAST, the three groupings of short, medium, and long SUET. SAM. WIND sounds with their accompanying practice words. Make up words of your own if you wish further O DAH-DAH-DAH SEA, TUM. SAW, practice. Speak the practice words in code. Say OAT. SUE, SAT. "TEE: DAH dit dit: MINE DAH-DAH-di-dit WED DAH-dit dit." P. di-DAH-dit SUM. MUD. IOU, Ifyoucanspeakwordsrapidlyand USE. SEMI, DARK distinctly in code, you'll have an easy time of it, when you learn to receive code, because the S GEORGE, DOWN, spoken code and transmitted code sounds are KIND, SORT, similar. Practice the figures in even gr oups: 11, MASK 22, 33, 44, 55, 66, 77, 88, 99, etc. Learn each letter by overall sound. Never count the dits and U di-di-DAH WORK, GROW, dahs. URGE, TUG, PULL

Short Sounds Practice Words W di-DAH-DAH WIGS. WORN. WET. WAKE, WALL E dit TEE, ATE, EAT. TEA. MEAT. MEET Long Sounds Practice tVords

**Zero is written as 0 to avoid confusion with B DAH-di-di-dit BAT. BALL. BEAT, the letter 0. 8 GLIB. GAB, JAB

133 INTRODUCTION TO SONAR Long Sounds Practice Words handkey. The shipor station to which you are attached has a practice handkeyyou can use. C DAH-di-DAH-dit CUT, CAM, COAT, Find a Radioman who will keycode groups CODE, CALF to you to help you inyour training. The sound produced by keying an oscillator resemblesthe F di-di-DAH-dit FIVE, FAT, FUSS, sound of code from thesonar transmitter. FEET, EFFECT After you learn the sound of eachcharacter at a slow rate of speed, it isnot difficult to reduce the time between characters H di-di-di-dit ACHE, HUSH, HAVE. and thus to HOLD, HOT copy at a much faster speed. But don't strive for speed before accuracy. Bea competent operator. Ma keeve ry J di-DAH-DAH-DAH JERK, JIM, JAR, t ransmissionandreception JAM, JAB accurately. Accuracy is much easierif you learn thefundamentalswell. Some code practice L di-DAH-di-dit exercises thatwill help you are included for LIKE, LAG, JELLY, your convenience. LOVE, LATE P di-DAH-DAH-dit PUSH, PAIR, POLE. CODE PRACTICE PART, HAPPY

EEE TTT Q DAH-DAH-di-DAH QUAY. QUEBEC. AAA 0110 I I I OSS 11110 PRP QUEEN. QUIZ, VI.M.M 000 SSE TTT AAA NON I I SSS

QUIT OSS 1 1 1 1 0 MM.M RRR 000 EES TTT I I I TTT SEE TTT I II V di-di-di-DAH VIM, VERY. VETCH, NON SSS 000 AAA NON SEE VAT, EVE AAA NON TTT000I II SSS 2. 1100 VVV DDD BBB SHE CCC WWW JJJ K DAH-di-di-DAH PPP 0110 VVV WAX, XRAY, LYNX. ODD BBB XXX CCC WWW SIX, EXAM JJJ PPP VVV DUO BBB CCC EKE< 111,:W DDD ERR BBB CCC LWW DUO VVV JJJ ( DAH-di-DAH-DAH YOUNG, YOKE, CCC WWW SKS PPP YAK, JERKY, DOD VVV JJJ L'UU RRP LI. L REF YAM GGG Z Z Z XXX YYY QQ0 PRO LLL EFF DOG QQ0 222 Yr/555 DAH-DAH-di-dit ZERO, BUZZ. 7.1QQ GGG 222 DLL YYY REP OFF LLD FIZZLE. QUILL, QQO RRR MXX 222 YYY LYNX LLL GGG LLL QQ1L":'/Y DUO Z Z Z XXX RRR LLD 4. 111 222 333 444 555666 777 888 Theonlywaytolearncode is by 999000 111 222 333 racticecontinualpractice.Thevalueof 444 555 666 77 888 ractice cannot be overemphasizedas you will 999 000 123456 789000 113 arn when you test yourself, with the help of 344 225 577668 800992 220 123 Dur shipmates. to find out how wellyou have 456 789 012 345678 905 599 weloped yourskillthroughpracticing by 5. VUIY Q 2 CX 0p )urself. S LEJPOSZPIFCVB 0555) 11 EBVPSTDOTMEG

Z X V E I 14 Ifyou II11 0 A E: ': havecarriedoutthe V A 0 V/r.; 0 11 commendations made up to this point,you are C IX 21. 0 RV 1:F.V5:WSXEDCRFOTGB ady to receive code transmitted to you on a :4I P'./ A XEDCRFVT 134 139 Chapter 8COMMUNICATIONS

CODE PRACTICE CODE PRACTICE OLVHM YBLUR MOHIZ OVICT FINXC 6. EBY 7B 5X1S 0 Z 2A 3C 5S 4 12 Fu 1F MSHTY VI ZNT EFILMQ ABLBE JNCYZ 5 D 8Q 4 T 6 U 9 Q EOS 5U1 YG 2 J4 S 3 E5T7Z8K6M9RIA2P.S7W8E982A BZWCN JNICDU TLZKL ABDEF ZVNEW KFREO LMXMV NHEM2 RNVUT KNXFC 3 Z 3 X 6 C 8 13 7 C 6 TE 8 V 7E35 yOF 1W 4 DEHLY HEMP AZCWI ZYSKQ IQAWM F 1 A 7 1588541N6C2K 3A9232602 11. NWZIH ZXCKA LinTGW WNLIPWBEOX

7. WI AN TY SX EC LV OD 01 SP TZ EC NU VA EH LM DQ ADXFR 3IQCA UTHAV NCE1P.P DREDC BM ZS CD QA IU SC PQ OW IE UR VT LA KS JO HF GM XVHRW CJ.MNJ FSTRO TNBLU JHKNI ZN X0 CV QZ WM EC RV TB YN UM IL OP AE SR DT FY (T)t."( RGBNS VCXTP 2TUBDCGFH5 HU 21 KO LO ZS MD CF VG BH NJ MK SW ME CR VT BY VXH7G 2219Y TX356 T148P BTOZX NU MI LO PS DO FI GY BU IN 211 HA MR TV TV YB NU

8. DE FT BY 72 VA 54 98 IM BT BT 1134 66 CV VF TG PROSIGNS 62 84 QA WS RP 54 20 BY 77 GY AA YF UH IJ VD BE 99 25 56 83 25 LA KS JD CY BU IN EB QV QV ZZ Procedural signals, called prosigns, are used K by radiotelegraph operators for the same reason 22 00TT75 44 VY 53 VS CW MC WH 66 FS SS ER FE thatprowordsareusedbyradiotelephone 26 CG PL IA LE FG QY 85 RI39 NE JE SI2537 AP talkers.Mostprowordshaveanequivalent

9. WNT AGR DTS ELY BFC NZX REH KCE HIJ ACE RNG TCV prosign,which,inseveralinstances,isan EPL ZSW QAB SHL GBT VRT GUM GYO DCM MSD ZAU YER abbreviation of the proword. You will notice in the accompanyimY, list of prosigns that some of DLN APG VNB EDX BWS UTA PHI KTZ HBY ALE RDC TOC them are overscored. Overscoring means that the ESN IUP PKJ NYH GHT DPP VED SWN VBT XFZ RDA FUO letters are to be sent as one character; that is, NYH OLX RWH MKY ATA NM; RGE SKZ KDG OKL OIX GLM without the normal pause between letters.

Prosign Proword Meaning Remarks AA ALL AFTER All after Used to identify AB ALL BEFORE All before portions of a WA WORD AFTER Word after transmission when WB WORD BEFORE Word before requesting a repetition.

OVER Go ahead and Every transmission transmit. ends with one or AR OUT End of trans- the other of these mission; no prosigns. reply expected or desired.

AS WAIT I must pause for a few seconds. AS AR WAIT OUT I must pause longer than a few seconds.

BT BREAK Long break Separates text of message from head- ing and ending.

135 INTRODUCTION TO SONAR Prosign Proword Meaning Remarks II Separative Used for all other separations in messages. Write it DE as a short dash. FROM From EEEEEEEEE...CORRECTiON I just made Corrected version an error. is sent immediately. EEEEEEE AR DISREGARD THISTRANSMISSION IMI SAY AGAIN Repeat

ROGER I have received all of your last trans- mission.

Sending measurement does not apply toevery key and operator; itis a matter of personal preference. Your ability to send code dependsmainly on Some operators like a closed two considerations. First,you must know the key, others an open correct key. "Closed" and "open"are terms for a short soundofthecharacteryouare and long gap. As the student attempting to transmit. Second,you must know progresses, further gap adjustment may be made to suit hissending the correct method for keying.Practicing the speed. Contacts that code aloud, as well as receivingit by oscillator, are too close have an effect should give you a good similar to weak spring tension.Contacts that are knowledge of code spaced too far have thesame effect as too much sound. The proper methodfor keying is your next concern. spring tension. Probably the first key you'll The final adjustment ofthe keyisthe encounter is the sidewise alignment of thecontact points. This unshielded telegraph key, normallyused on alignment is controlled by the practice oscillators on shipboard trunnion screws and on station at either side of the key. Ifthey are too tight, circuits. The key must beadjusted properly before you can transmit clear-cut the key lever binds. If theyare too loose, the characters. A contacts have sidewise play. Usually,when the handkey, with parts labeled, is shownin figure sidewise 8-1. alignmentiscorrect,nofurther adjustment is required. A spring tensionscrew, behind the key From the beginning button, c, .1trols the amount of you should learn the upward tension correct way to grasp the key.The following on the key. The tension desired varieswith instructions, in the order listed, operators. Too much tensionforces the key constitute the button up before proper procedure for becomingaproficient thedahs are completely operator: Do not hold the key tightly, formed; spacing between charactersis irregular, but let and dits are not clearly defined. your fingers rest lightly on the key knob.Your If the spring thumb rests against the side;your forefinger tension is very weak, charactersrun together and rests on top of the key: the space between charactersis too short. your third finger is bent and relaxed with the remainingtwo fingers. The gap between the contacts,regulated by Speed and accuracy of transmissiondepend, he space adjusting screw at theback of the key, toalarge extent, on acquiring the hould besetat1/16for beginners. This proper movements of your wrist and handwhile 136 141 Chapter 8COMMUNICATIONS operating the key. To close the key, your wrist proficient in radiotelephone procedures because moves upward and your hand rocks downward those techniques are used for underwater voice toward your fingertips. To open the key, these communication. When CW (radiotelegraph) is two movements are reversedyour wrist comes used, you must be able to send and receive down and your hand rocks back. A dah should M orse codewi thoutCausingdelayor be about three times as long as a clit. misunderstanding. The most widely used underwater telephone Conditions of the water have a bearing on installation is the AN/WQC-2 (and modification) the speed at which you will be able to transmit. sonarset,commonlycalledSEATALK. At times you can transmit rapidly and your Although intended for use by sonar control signals will be clearly audible. Other times you personnel, some installationsprovide remote may have to go very slowly, otherwise your dits voice operation from the bridge. The WQC-2 anddahscannotbedistimzuishedbythe operates at frequencies that are compatible with receiving operator. allother existing underwater telephone units. Figure 8-2 shows the front panel controls of the AN/WQC-2. As can be seen in figure 8-2, the UNDERWATER COMM UN ICATIONS AN/WQC-2 has all of the capabilities of the olderAN/UQC-1 (fig.8-3),withmany For many reasons itis necessary for a ship modificationsforbettertransmissionand and a submerged submarine to communicate reception. with each other. Of paramount importance is The range of transmission varies with water the safety of the submarine and its crew. During conditions, local noise level, and reverberation exerciseperiods,theshipcanadvisethe e ffects.Undernormalsonarconditions, submarine when it is safe to surface. Should an however, communication between ships should emergency arise aboard the submarine, the ship be possible at ranges comparable to those of the can be so informed. Exercises can be started and UQC-1. Under the same conditions, submarines stopped, or one in progress can be modified, by achieve a greater range. If the submarines are usingtheunderwatertelephone.Attack operatingin a soundchannel,the accuracy can be signaled by the submarine to communicationrangemaybemany miles the attacking ship. Sonar Technicians must be ueater than that achieved by surface ships. Localnoise, caused by ship's movement through the water, machinery, screws, etc., can SPACE ADJUSTING BINDING LATERAL reduce the range to less than half the normal SCREW POST BLOCK TRUNNION SCREW range.Severereverberationeffects may also LOCI< NUT causea reductioninrange,butyou can SPRING TENSION SCREW overcome them by speaking slowly, pausing 1 LOCK NUT after each word to let the echoes die out. At very short ranges, it may be impossible to reduce BINDING KEY LEVER POST thereceivimz gaintoa comfortable speaker outputlevel.Then, you must speak softly, holding the microphone away from your lips. \ ,

(..,;::\i...T .,...___ _4/ VOICE PROCEDURE <,..._..---_-,-,------____ -,-,,,,.:. .,.,..i,s.:____-rr.,," \ T RUNNION ...... \ 1 ,-..._ . SCREW .__. As mentioned earlier, you will use the smile 1 \ \ KEY BUTTON voice forunderwatervoice LOCI< NUT procedures asforradiotelephone LATERAL BLOCK ,--- CONTACTS communication TENSION SPRING transmissions.In other words, youcallthe station for which you have a message, identify 76.8A yourself,send your message, and endthe Figure 8-1.Handkey. transmission with either OVER or OUT. 142137 INTRODUCTION TO SONAR

Calling and Answering With communication established, COPY CAT sends his message: Hereisan example of acallfroma submarine (call sign COPY CAT) to an ASW ship SHARK FINTHISIS COPY CAT (call sign SHARK FIN). Dashes shown are not BREAKAM AT EXERCISE DEPTH. actually sent but indicate pauses the operator READY FOR COMEXBREAK-- makessothathistransmission canbe OVER. understood more easily. SH ARKFINgives a receipt,usingan SHARK FINTHIS IS COPY CATOVER. abbreviated call: COPY CATTHIS IS SHARK FINOVER. THIS IS SHARK FINROGEROUT.

MODE XM IT POWER SELECTOR SELECT LEVEL SWITCH SWITCH SWITCH

CW KEY

LISTEN SWITCH

POWER XMIT INDICATOR LIGHT VOLUME HIGH CONTROL POWER ON INDICATOR LIGHT

XDCR VOLUME DIMMER ON-OFF SWITCH LOW CONTROL SWITCH CONTROL

141.296 Figure 8-2.--AIWINGIC-2 front panel controls.

138 1 A '1 Chapter 8COMMUNICATIONS

Following is an example of a related series of Waits messages between ships conducting an ASW exercise. When an operator finds it necessary to delay transmission momentarily, he sends the proword S EA POW E R THIS IS TOP HAT WAIT. If the delay isfor longer than a few BREAKSTANDBY MY "BASSET" moments, the transmission is WAIT OUT. A new PORT-2 MIN.BREAKOVER. call is made when communication is resumed. TOP HATTHIS IS SEA POWER BREAKROGERWILL REMAIN Repetitions CLEAR OF YOU UNTIL COMPLETION YOUR ATTACK The request for a repetition is SAY AGAIN, OVER. not "Repeat." Used alone, SAY AGAIN means "Repeat all of your last transmission." Followed THIS IS TOP HAT.ROGEROUT. by identification data,itmeans "Repeat the indicated portion of your transmission." The Correcting an Error answer to SAY AGAIN is I SAY AGAIN, followedbytherepetitionrequested.For example, COPY CAT asks SHARK FIN to If you make an error in transmission, send repeat all of his last transmission and SHARK the proword CORRECTION immediately. Go FIN complies. back to the last correctly sent word, repeat it, and continue with the correct version. Example: THIS IS COPY CATSAY AGA1NOVER. CuPY CATTHIS IS SHARK FIN THISISSHARK FINI SAY BREAKROGER YOUR YFILOW AGAINBREAKROGER YOUR ALL HERECORRECTIGNALL YELLOWALL CLEAR TO COME TO CLEAR TO COME TO PERISCOPE PERISCOPE DEPTHBREAKOVER. DEPTHBREAKOVER. If COPY CAT missed only the word DEPTHS, he would frame his request as follows: THIS IS COPY CATSAY AGAINWORD AFTER PERISCOPEBREAKOVER. When COPY CAT has the complete message, he sends a receipt.

Cancelin, a'...r3ssage

To cancelamessageinprowess, cease sending immediately and transmit the proword DISREGARD THIS TRANSMISSION. Example: SHARK. FIN'S operator bmins message, then is ordered to delay it. COPY CATTHIS ISSHARK FIN BREAKTAKE STATION MY PORT- 71.71 DISREGARD THIS TRANSMISSION Figure 8-3.AN/UQC-1 control unit. BREAKOVER. 141 139 INTRODUCTION TO SONAR

Once a message is receipted for, it cannot be transmission capability, the AN/BQC can emita canceledbymeansoftheproword 24.26kHzcontinuoustoneforhoming DISREGARD THIS TRANSMISSION. Instead, purposes. The AN/BQC-1B and C also provide a a new message must be sent. 9.58 kHz tone for homing. SUBMARINE COMMUNICATION Submarine rescuevessels have equipment 1IETHODS capable of detecting and homing on the tone. With all batteries in good condition, 72 hours of The AN/WQC underwater telephone is the continuoustonetransmissionarepossible. ;ubmergedsubmarine'sprimarymeansof Range of the homing signal is 2000 to 5000 :ommunicating with surface ships.For this yards. eason,duringexerciseperiods,shipsare Coloredflaresand smoke signals afford equired to man the WQC continuously. In another means of communication. Blackor tddition to its required use for safetypurposes, greensignalsareused by the submarine to he WQC is used throughout an exercise by ships indicate the simulated firing of torpedoes and to .ndsubmarinesforsending attacksignals, mark her position. A yellow flare or smoke )btaining range checks, transmitting sonar short signifies the submarine intends to surface. Ships ignals, and for several other purposes. Subject must then clear the area and keep other shipping o equipment limitations, keyed sonar is the away. A designated ship notifies the submarine acondary means of underwater communica- that the siLmal was sighted and informs him ions. Many submarine sonars do not have when it is safe to surface. A red flare denotes V capability. trouble. It means the submarine is carryingout Emergencycommunicationequipment emergency surfacing procedures. If the flares are arried by a submarine include a radio anda repeated or if the submarine fails to surface ,tlephone. The radioisbattery-powered and within a reasonable length of time, itcan be oats to the surface upon release through the assemed he is disabled and requires immediate ignal ejector.Onceonthesurface,it assistance.You must make every effort to utomaticallytransmitsonemergency maintainsonarcontactandestablish idio frequencies. communications by any means possible, but Theemergencytelephone,designated preferably by voice. .N/BQC-1A,B,C, is also battery-powered and is Detailed pyrotechnic, sonar, and explosive Drtable.Ithasthe same voicefrequency signal information is contained in FXP 1. All laracteristics as SEATALK, with a range of Sonar Technicians must become familiar with )out5000yards.Theusualinstallation the signals in that publication. Therescue of a 7ovides onesetintheforwardescape disabled submarine's crew could dependon your mipartment and one setin the aft escape abilitytoestablishandmaintainreliable )m pa rt ment. In additiontoitsvoice communications.

145 140 CHAPTER 9

TEST EQUIPMENT; TEST METHODS; MAINTENANCE

Sonar Technicians must assist in the upkeep Manual,Chapter9670; Handbook of Test and repair of the sonar equipment aboard their Methods andPractices,NAVSHIPS ship or station. Consequently, you must become 0967-000-0130; Safety Precautions .Thr Shore familiar with the types of test equipment, test Activities, NAVSO P-2455; and Nary Safety methods, and safety precautions to be observed Precautions for Forces -Afloat, OPNAVINST when using or working on electronic equipment. 5100.19. Naturally, a knowledge of electronics is required also. Information related to the electronics field GENERAL SAFETY can be found in Basic Electricity, NAVEDTRA PRECAUTIONS 10086, and Basic Electronics, Vol.I and II, NAVEDTRA10087.Informationon the Wheneverpossible,deenergizethemain selection, care, and use of hand and portable power input to any equipment before you work power toolsis contained in Tools and Their on it. Remember, though, that there still may be Uses, NAVEDTRA 10085. power inthe equipment from such external sources as synchros, remote indicator circuits, and instrument heater elements. When you open SAFETY the switch in the main supply (or any other power switch), indicate the switch is open by Maintainingelectricalandelectronic attaching to it a tag reading "THIS CIRCUIT equipment is a dangerous business. Every year, WAS ORDERED OPEN FOR REPAIRS AND lives are lost aboard ship due to electric shock; SHALL NOT BE CLOSED EXCEPT BY and, in most instances, death could have been DIRECT ORDER OF (your name, or name of avoided byobservingappropriatesafety person in charge of repairs)." precautions. If you must work on an energized circuit, Most people treat with extreme caution a observe the following safety precautions. circuit containing serveral thousand volts, but actwithindifferencetowardthe common I.Never work alone. Have another man, household current. Yet, 115 volts a.c.isthe qualified in first aid for electric shock, present at prime cause of death from electric shock. Cases all times. He should also be instructed in how to have been recorded of fatal shocks from such secure the power. Nuipment as portable drills and grinders, fans, 2.Use insulatingrubbermatting.The ;movie projectors, and even coffee pots. You matting must be kept clean and dry. Wear must continually be alert when working with rubber gloves,ifpossible, and use insulated :lectricity, and you must follow strictlyall tools. Remove rings and watches. )ertinent safety precautions. 3.Use only one hand whenever possible. Although some safety practices are given in Keep the other hand behind you or in your :his chapter, you should become familiar with pocket. :he safetyinstructionscontained in the 4.Do not indiscriminately stick your hand 'ollowingpublications: Nil VSE/1 Technical into an enclosure.

141 146 INTRODUCTION TO SONAR

5.Have ample illumination. SpLDER 6.Never short out, tamper with, or bypass ,L'InR) an interlock.

Beforeworkingon a deenergized component, discharge all capacitors in the unit. A capacitor is a device for temporarily storing electrical energy. Successive small charges are

built up in the capacitor for later release. Sonar GROUNDING GROUNDING transmitting equipments utilize this feature by CABLE CLIP building up electrical energy in the equipment's capacitor bank between each ping. A trigger 1.1 pulsethenreleasestheenergyinasingle Figure 9-1.Shorting bar. high-poweredpulse.Nearlyall typesof electronic equipment use capacitors of varying sizesandtypes.Normally,thelargerthe or open ground strap connection, however, a capacitor, the higher the electrical charge it will potential differenceis established. Should you hold for a greater length of time. Onmany then come in contact with the equipment,you electronicequipments,chargesupwardsof become the ground strap. In other words, the 14,000 volts are present. Usually, such large current passes from the equipment through you charges aredischarged by mechanical means toground,resultinginanelectric when the equipmentis opened. Many other shockpossibly a fatal one. You mustensure, capacitors,however,must bedischarged therefore, that all ground connectionsare tight manually by the man working on the circuit. and free of foreign matter, such as dirt,grease, To drain capacitor charges, the deviceyou or paint, that might interfere with the required will use is the shorting bar, shown in figure 9-1. metal-to-metal contact at the ground connection The shorting bar usually consists of a copper rod points. which has an insulated tulip on one end. A heavy Fuses are another source of potel...., braided cable is soldered to the rod near the to the careless Sonar Technician. The purpose of grip. On the free end of the cable is a battery a fuseistoprotectelectriccircuitsand clip. When using the shorting bqr, first secure components. A fuse blows because more current power to the equipment, clamp the cable clip than the fuse can handle tries to pass through it. firmly to the frame or other good ground, then The cause of the current overload may bea dischargeeachcapacitorbyholdingthe momentary surge in ship's power, or it may be a insulated handgrip and touching the terminals of shortcircuit.Whateverthecause,two the capacitors withthe copper rod. Always precautions must be observed when replacing ground the capacitor at least twice because the fuses. First, use a fuse puller, even ifpower is capacitor'schargemaynotbecompletely secured. (Althoughitisdesirabletosecure drained by one application of the shorting bar. power to the affected circuit, itis not always Practically all electronic equipments have a necessary or practical to do so.) If you use a metal grounding strap connecting the equipment screwdriver,pliers, or your bare fingers,you chassis to the ship's hull. The purpose of the may receiveasevereelectric shockif you grounding strapisto place the equipment's contact adjacent livecircuits. Second, always frame andthehullatthesame electrical replace a fuse with one having the same rating. potential, thus permitting personnel to touch Substitutingahigher ratedfuse may cause the equipment without danger of receiving an serious damage to the equipment. If the chcuit electric shock. As you know, a difference in does not burn out, dangerous potentialsmay potential is what causes current to flow. If a exist that normally would not be present, thus component shoulddevelopashorttothe endangering servicingpersonnel. chassis, the short-circuited power will bleed ot'f Cathode ray tubes (CRTs) are used in all to round through the strap. If there is a faulty sonarequipment.Theyare ofrugged 147 142 Chapter 9--TEST EQUIPMENT: TEST METHODS: MAINTENANCE

construction and normally have a long life. They component. One reason is that measurement of do requirereplacement from timetotime, anelectricalvalueof a component. hy an however,anda fewprecautionsmustbe equipment having its own rzroun d level value, observed inhandling them. A CRT must be could reflect the difference in potential between handled gently to prevent breaking it and to the component and the test equipment. Another avoid displacingits internal elements. Always reasonisthat, if the ground level of the test place a CRT face down on cushioning material. equipment differs from that of the component If the tube is broken, don't handle the alass with being measured, a condition of electrical hazard bare hands because the tube's inner surfar,is may result, and maintenance personnel may be coated with a toxic material. Gloves and special shocked. face masks are available to personnel handling Externally powered equipment. such asa CRTs. tube tester, is grounded to the frame of the ship through a standard three-wire electrical cord and SAFETY WITH plug. A firm connection to thepower receptacle POWER TOOLS is all that is needed to ground such equipmentso thatit willbesafetothetouch.Other Hazards associated with the use of portable equipment perhapsolderorrepairedtest electricpower toolsincludeelectric shock, equipmentmay notbeequippedwiththe bruises,cuts,falls,particlesintheeyes. three-wire cord. If itis not so equipped, the test explosions, and the like. All Sonar Technicians equipment should be grounded, with a separate should become familiar with the safety practices cable running from its chassis or housing to the contained in .V/1 VSEA TechnicalManual, frame. Always check tosee that the ground Chapter 9600. Section H. Following are some of connection is firm and thatitis sufficient to thegeneralsafetyprecautionsyou should take any electrical load supplied to it. observe when working with power tools. ELECTRIC SHOCK 1.Ensure that the tools arc grounded in accordance with articles 60-25 through 60-27 and 60-29 of the .V/1 VSE/1 Technical Manual. Electric shock is a jarring, shaking sensation. 2.Avoid. if possible. using spliced cables. You may feel as though someone hit you witha 3.Carefully inspect the cord and plug. If sledgehammer. Althoughusuallyassociated the cord is frayed or the plug, appears damaged. with high voltage, fatal shocks often are received replace them. from 115 volts or less.If your skin resistance 4.If an extension cord is used, connect the (which varies) becomes low enough, a current of cord of the power tool into the extension cord. 100 milliamperes (.100 ampere) at115 volts. then connect the extension cord into the power sustainedforonlyacouple of seconds,is receptacle. When your work is finished, unplug sufficient to cause death. the extension cord from the power receptacle, then unplug the cord of the power tool. Symptoms and Effects 5.Wearsafetygogglesforprotection against particles that might strike your eyes. 6.Make sure the cables do not present a The victim of an electric shock is very pale: tripping hazard. his skin is cold and clammy. His breathing (if he is breathing) is irregular, shallow, and rapid. He may sweat profusely, and his eye pupils will be GROUNDING TEST dilated.In some cases he will be unconscious EQUIPMENT and have an extremely weak pulse. or no pulse. In severe cases he will have no heartheat. Vital Equipment that measures electrical values of organsinthepath of the current may he component parts must never assume a ground damaged(usuallyduetoheat)and nerves level different from that of the chassis of the paralyzed.

143 148 INTRODUCTION TO SONAR

Rescue and Treatment The mouth-to-mouth method of artificial respiration is preferred. Next in preference is the The first thing to do for a victim of electric back-pressure, arin-liftmethod.Detailed shock is to remove him from contact with the informationonadministeringartificial circuit. The best method is to open the switch if respiration can be found in Standard First Aid you can chi so without too much delay. If an ax TrainingCourse,NAVEDTRA 10081. is handy and the power cable is accessible, the Whichever method youuse,theimportant cable can be cut, assuming that it would take objective is to start immediately. too long to find the proper switch. If there are no ready means for cutting the power, use any dry nonconducting material to pull the man TEST EQUIPMENT free; a belt, clothing, a piece of line, a wooden stick,orasound-powered phone cord.Be Electrical equipment is designed to operate extremely carefulthat you don't become a at certain efficiency levels. Technical instruction victim yourself. books,andsheetscontainingoptimum Thetreatmenttogiveashock victim per fo rm a n cedatasuchasvoltagesand dependsonhisconditionwhetherheis resistancesarepreparedforeachNavy breathingornot.Thefollowingcare is equipment. The instructions are intended to aid prescribed when the man is breathing. the technician in maintaining the equipment. As a Sonar Technicain, you will work with I.Lay victim on his back, with his head many different types of test equipment. This lower than his feet. Loosen the clothing about chapter discusses some of the basic equipments his neck and abdomen so he can breathe freely. such asmultimeter,oscilloscope,signal Keep himwarm,butnothot. SUMMON generator,frequencycounter, and transistor MEDICAL AID. tester. If these test equipments do not sound 2.Keepthemanstill.Electricshock basictoyou, keep inmind thatas sonar weakens the heart, and any muscular activity on technology becomes more complicated, sonar his part may cause the heart to stop functioning. equipmentbecomesmoresophisticated.It follows,then,thattest equipment used to 3.Normally, no liquids should be given. maintain the sonar equipment must become Never give stimulants nor sedatives. more sophisticated also. 4.If the necessary materials are available, apply a small amount of Vasoline to his burns, r.nd cover them with a sterile dressing to prevent 1 I I I infection. CURVESHOWINGPOSSIBIUTYOF SUCCESS PLOTTEDAGAINSTELAPSEDTIME BEFORE STARTOF RESUSCITATION Resuscitation

Iftheshockvictimisnotbreathing, immediate efforts must be made to revive him even though he may appear to be dead. (Victims of severe electric shock sometimes appear as NM though rigor mortis has set in.) The effort must -wwin. be continued until medical personnel can take 5 10 15 20 5 over or until a competent person declares the TIME INMINUTES victim to be dead. Speed in beginning artificial respiration is of the utmost importance. Figure 9-2 shows thatthe victim'sbest chance of 71.101 survivaldepends onbeginningresuscitation Figure 9-2.Importance of speed in commencing within 5 minutes. IS 9 artificial respiration. 144 Chapter 9--TEST EQUIPMENT; TEST METHODS;MAINTENANCE

MULTIMETER multimeterused in theNavytoday,the electronicmultimeter ME-(1)/U. .,1sa Sonar The multimeter is a multipurpose meter that Teelmician. you will become familiar with these can measure resistanees. a.c. and d.c. voltages. meters. and d.c. milliamps. Its versatility and portability elminate the need for carrying several meters for testpurposes. The usual precautions must be OSCILLOSCOPE observed when making resistance and voltage measurements. When measuring d.c.voltage. The oscilloscope is one of the most valuable proper polarity must be observed. The face of pieces of test equipment available to the Sonar the instrument has separate graduated scalesto Technician.Withtheoscilloscope you can indicate the three values that can be measured. determine a signal's frequency, pulse width, and Be sure you read the proper scale. Figure 9-3 amplitude; measure voltages and phase relations; showsthe front view of one of themost and observe signal waveforms. The latteruse is common multimeters used in today's Navy, the particularlyhelpful sincemanytechnical A N/PS M-4 D. Figure9-4showsanother manualsinclude(intheirservicingblock diagrams) waveforms at various test points.

4.133 4.133 Figure 9-3.Multimeter AN/FSM-4D front view. Figure 9-4.Electronic rnultirneter ME-6D/U.

150 145 INTRODUCTION TO SONAR

71.130 Figure 9-5.Typical oscilloscope, AN/USM-281.

The oscilloscope(fig.9-5)consists of a of a.c. energy. both audiarequency and radio cathode ray tube, vertical and horizontal beam frequency.Thesesourcesarecalledsignal deflectingcircuits,sawtoothvoltagesweep generators. They are used in testing and aligning circuits,andnecessarypower supplies. The transmitters, receivers, and amplifiers: they are signal to be observed (a sine wave, for instance) alsoused whentroubleshootingvarious is applied to the vertical deflection plates. If that electronic devicesandsometimes when were the only signal applied, all you would see measuring frequency. on the scope would be a straight. vertical line. To have the sweep conform to the sine wave The principal function of a signal generator voltageontheverticaldeflectionplates,a is the production of an alternating voltage of the sawtooth (linearly increasing) voltage is applied desired frequency and amplitude which has the simultaneouslytothehorizontaldeflection n eess a ry m od u I anon forthe te.st or plates. The result is that the sweep moves across measurement concerned.Itis very important the scopeatauniformrate,following the that the amplitude of the generated signal be fluctuations of the signal applied to the vertical correct. In many generators, output meters are plates. When the sawtooth signalreaches its included in the equipment so that the output cutoff point, the sweep returns rapidly to its may be adjusted and maintained at a standard starting point to await the next sawtooth signal. level over a wide range of frequencies. The measurement of frequency, calibration, and other special situations requires the use of a When using the generator, the output test synchroscope. whichisan oscilloscope with signalis coupled into the circuit being tested, special circuits added, such as sweep triggers and and its progress through the equipment is traced marker generators. The sweep commences only by the use of high-impedance indicatinr devices when a signal is received. such as vacuum tube voltmeters or oscilloscopes. In many sigmil generators, calibrated networks SIGNAL GENERATORS of resistors. called attenuators, arc provided. These are used to regulate the voltage of the output signaland alsoprovide correct In the maintenance of electronic equipment. impedancevaluesformatchingtheinput itis often necessary to employ standard sources impedance of the circuit under test. Accurately

5i 146 Chapter 9TEST EQUIPMENT: 'FEST METHODS:MAINTENANCE

71.131 Figure 9-6.Signal Generator.

calibrated attenuators are used since the signal TRANSISTOR TESTER strength must be regulated to avoid overloading the circuit receiving the signal. Figure 9-6 isa Laboratory transistor test sets are used in typical signal generator. experimental work to test all characteristics of tNi nsistors.Formain tenanceand repair, however, itis not necessary to check all of the FREQUENCY COUNTER transistor parameters. A check of twoor three performance characteristics is usually sufficient The AN/USM-207 11'ig. 9-7) isaportable, to determine whether a transistor needs to be solid-stateelectroniccounterfol precisely replaced. 'kV() of the most importantparameters measuring and displaying on an 8-digit numerical usedfortransistortesting arethe transistor readout the frequency and period ofa cyclic current gain (Beta) and the collector leakageor electricalsignal,thefrequency ratio of two reversecurrent (leo). These are discussedin signals, the time interval between two pointson 13asie EhTtronics, Vol. 1, NAVEDTRA I 0087-C. the same ordifferentsignals. and thetotal Semiconductor test set AN/USM-206A number of electrical impulses (totalizing). The 9-81 is a rugged field type tester designedto test counter also provides the following types of transistors and semiconductor diodes. Theset output signals: willmeasuretheBetaof atransistor,the resistance appearing at the electrodes andthe I.Standard signals from 0.1Ilz to 10 MIlt reverse current of a transistor Or semiconductor in decade steps derived from a I MI Iz frequency diode, a shorted or open condition ofa diode, standard, frequency dividers, anda frequency the forward trans-conductance ofa field effect multiplier. transistor.andtheconditionof'itsown 2. laput signals dividedinfrequency hy batteries. factors from 10 to 10by a frequency divider. 3.Digitaldataof the in measuremen t TEST METHODS fo u r-li nt binary-coded-decimalform wi t h decimid point and control signals for operation When apiece of sonar equipment breaks of printers, data recorders, or control devices. down, it may he your job to locate the trouble

147 INTRODUCTION TO SONAR

and restorethefaultycircuittoits proper much easierif broken into successive, logical operating condi6on. The means by which you st cps. Fignre9-9shows a general findthefaultycomponent is called troubleshooting procedure. StepsI through 5 troubleshooting, which consists of logical resting are followed in locating the trouble. Steps 6 and methods.Troubleshootingaidsinclude 7 are carried out in making repairs. Sometimes troubleshooting charts, servicing diagra ins, and steps 2,3.4, and5 may be elinhnated, but never voltage and resistance charts. steps Cu and 7. Troubleshootingcharts list various equipment malfunctions,the probable cause of TERMINAL DESIGNATIONS each.andthenecessarycorrectiveaction. Servicing diagsams showtestpoints, desired waveforms, proper voltages and other re ht ed Whencarryingoutyour troubleshooting servicing Mformation.Voltage and resistance procedures. you will find that many test points charts show the normal voltage and resistance arc located on ternnnal boards. Wiring diagrams, which aid you in tracing a circuit from one unit valuesat thepins of connectors and tube sockets. to another, indicate the terminal connections of each circuit in each unit. You must understand, .Althoud much of the equipment you are therefore. the system used for marking terminal required to maintain is quite compl,:, the job is boards and conductors as set forth inDictionary

RADIO FREQUENCY ELEc IRONIC OSCILLATOR FREQUENCY 0-I267/USM-207 CONVERTER (HIDDEN) CV -1921 USM -207

PANEL PROTECTOR

I PANEL PROT ECTOR

DIGITAL READOUT ELECTRONIC COUNTER POWER LIGHT CONNECTOR CP-814/USm -207 RE CABLE ADAPTER UG-274 B/u COUNTER COVER CONNECTOR CW-BOI/USm-207 ADAPTER UG- 273

POWER CABLE CONNECTOR ADAPTER UG-I035/U RE CABLE

CONNECTOR DIGITAL READOUT ADAPTER ELECTRONIC COUNTER RE CABLE UG -255/U AN/USM -207

PRINTED CIRCUIT RFTED PCUI I BOARD EXTRACTOR BCt.RD EiT ENDER

162.7 Figure 9-7.Digital readout electronic counter AN/USM-207.

153 148 Chapter 9TEST EQUIPMENT; TEST METHODS; MAINTENANCE of S tan da rdTerminalDesignationsfin. Electronic Equiinnent, NAVSEA 900,186. TRY TO LOCATE THE TROUBLE BY OBSERVING THE CIRCUIT'S FAULTY OPERATION

Terminal Boards TRY TO LOCATE THE TROUBLE BY USING EYES AND NOSE i2

LOCALIZE THE TROUBLE AT THE FAULTY SECTION BY TESTING TECHNIQUES Terminal boards are marked with a three-or four-digit number preceded by the letters TB. LOCALIZE THE TROUBLE AT THE FAULTY STAGE BY The first one or two digits of the TB number TESTING TECHNIOUES represent the unit number in the equipment. LOCALIZE THE TROUBLE AT THE FAULTY C RCUIT OP PART This number is assigned in a logical order. The BY TESTING TECHNIQUES 5 last two digitsrepresent the terminal board REPLACE OR REPAIR THE DEFECTIVE PART number in a unit, starting with 01, 02, 03, etc. 16 Thus, terminal board TB 1003 indicates the 3rd .....::) LEST THE CIRCUIT'S OPERATIONREADJUST THE C,RCUIT)7

12.259 Figure 9-9.Troubleshooting procedure.

terminalboardinthe10thunitofthe equipment.

Terminal Markings

Markings of termimlis on terminal boards indicate a specific function for the following circuits: (1) common primary power circuits, (2) ground terminals, , common servo and synchro circuits, (4) video circuits. (5) trigiter circuits, and (6) audio circuits. The breakdown of these categoriesintospecificfunctions,withthe terminaldesignationofeach, is listedin NAVSEA 900,186. They arecalledrigidly

E B assigned designations.. DIODE IN/CKT FE T. es BETA PN: BATT Terminals wlic)se functions do not Call uncler tHus E-B-- o the categ,ories listed are assigned desiunatic)lis ill BAT.2 T-e accordance withNAVSEA900,186.Only BAT. 1. 00 s C-E -ROLARITy RANGE terminals that are connected together externally ICO. ICES ZERO ;CES 2 5 A P have exactly the sanie designation withinany READ given equipment. -IcEZSEPO-

0OviER COARSE F INC Conductor Marking 42-W

()II the conchictor lead, at the end near the 162.121 point of connection to a ternlinal post, spalJletti Figure 9-8.Semiconductor test set sleevingisuseclasamarKing material and AN/USM-206A. insulatc)r. The slec\ing is engrawd with indelible

149 1 5 INTRODUCTION TO SONAR

ink or branded with identifying numbers and Cable Marking letters by a varitype machine, and slid over the conductor. When doing maintenance or repair work, The order of marking is such that the first you may have to trace a cable from one section appearing set of numbers and letters, reading of the ship to another, examining the cable for fromlefttoright, is the designation damage that might be the cause of equipment corresponding to the terminal to which that end breakdown. Cables are identifieJ by metal tags of the wire is connected. Following the terminal that give information on the cable's use. Tags are designationisadash and then the number attached to the cable as close as practicable to (without TB) of the terminal board to which the each terminal connection, on both sides of decks other end of the conductor is attached. There is and bulkheads, and at intervals of about 50 feet. anotherdashandthedesignationof'the Formerly, colored tags were used to classify the particular terminal to which the other end of the necessity of' the cable, and you may still see wire is connected. some of them. Red indicates a vitalcircuit, Figure 9-10 shows how terminalboards, yellow :1semivital circuit, and gray a nonvital terminals,andconductorsarcmarked. The circuit. lower portion of the illustration, for example, shows a conductor running from terminal 2A on 'Mecabledesignationinformationisa TB101 to terminal 7B on TB401. The spaghetti combination of letters and numbers, consisting sleeve on the conductor attached to TB101 is of aservice letter, circuit letters, and cable marked 2A-401-7B, indicating the other end numbers. A typical cable designation is RSK3. of the conductor is attached to terminal 713 on The service letter ( R ) means the cable supplies TB40 I. The sleeve at terminal 713 of T13401 is electronic equipment: thecircuit letters (SK) marked 7B-101-2A, indicating the other -rid denote scanning sonar; and the number (3) of the conductor is attached to terminal 2A on means itis the third cable in the scanning sonar TBI01. If you must remove a conductor from a circuit. A completelist of cable designations terminal, the first set of letters and numbers tells may befound inchapter 9600 ofNA VSE4 you to which terminal it must be reconnected. Technical :Vanual.

RESISTORS TE74111.41. L,N!T A SpGrE NO" ; 10) t lh :C A resistor is a device used to limit current 4 ;-x-I C5: flow. Itis of either the fixed or variable type.

TE; NAL Resistors are tested with an ohmmeter after the resistor is disconnected from the circuit. This actionprevents damage tothe meter from circuit voltage and ensures that only the resistor beim; tested gives a reading on the meter. Before conducting the test, set the meter to the proper scale, touch the ends of the meter test leads together, and adjust the meter to obtain a zero reading.

Fixed Resistors

Fixed resistors may be made of wire, wound ori a core and coated with ceramic, or they may lc madc of carbon. They have either axial or :.adialleads, and a wattage rating according to Figure 9-10.Conductor and terminal markings. the amount of heat they dissipate. in general,

150 155 Chapter 9TEST EQUIPMENT; TEST METIIODS;MAINTENANCE

carbonresistorsarerated1/2to2watts. code given in table 9-1is used to interpret the Wire-wound resistors usually are rated above 2 resistor markings. You can easily memorizethe watts. color code. Resistance valueisindicated by colored A resistor always has three (sometimes four) markings on the resistor. The standard color resistance value indicators. Two methodsarc used to color code fixed resistors. In figure 9-11, the axial-lead typeis shown to the left; the Table 9-1.Standard Color Code for Resistors radial-lead type is shown on the right. Resistance value is determined as follows: Color Aiodicates the first significant figure; color B indicatesthe Significant secondsignificant Color figure or Decimal Resistance figure; color C givesthe number ofmultipliertolerance multiplier (number of zeros): and color D is the zeros percentage of tolerance. If thereis no fmirth color, the toleranceis20',;;.Assume that an Black. . Percent ± axial-lead and a radial-lead resistor each havethe Brown .. 1 following color code marking: Ared, B--green, Red 2 Corange, and Dgold. Referring to table 9-1, Orange . . 3 you find that the first significant figure is 2, the Yellow . 4 second significant figure is 5, and the multiplier Green .. 5 is1000 (three zeros). The resistance valueis Blue 6 25,000 ohms, or 25K as it sometimes ismarked Violet . . 7 Gray . 8 on a schematic diagram. The tolerance is 5%. A fixedresistoris White. . . 9 tested by placing an Gold ohmmeter lead on each resistor lead. For the . 0.1 5;J)* SAver 10(K)* r.2sistor used in our example.a reading of 24K to No color. 20(M) * 26K ,vould be acceptable. ow-power, \vire-wound resistors have axial *Symbol ciesignation alternatp forcolor. leads and are color coded similar to the regular axial-lead resistor, except that band A is double width. 20.373

A 8 C axial C A B hads radial color kads Bond A indicates first s gnificant 11; ;re of resistancevalue in ohms. Body A Band B indicates second 5 gnificant flgore End B B,nd C indicates decimal multiplier. Band C or dot Band D if any, indicates tolerance in pecent aboutnominal resistarice Band D value. if no color appears in this position.tolerarzce is 20%. wS, urn color coded ,,,, A

20.374 Figure 9- 11.Color code for axiai-lead and radial-leadfixed resistors.

151 INTRODUCTION TO SONAR

RESISTANCE WIPER WIPER RESISTANCE ELEMENT ELEMENT

TERMINAL- TERMINAL 1 2 TERMINAL 1 TERMINAL 2 W IPE R ( TERMINAL 2 ) TERMINAL 3

TERMINAL I TERMINAL 1

WIPER (TERMINAL 3) 71,94 F igu re 91 2.R heostat. TERMINAL 21

Variable Resistors 33.75 Variable resistors areor1.Vt.k) general types: F igure 9-13. Potentiorneter. may be rheostats or potentiometers. A rheostat normallyisused to adjust the current in a circuit without opening the circuit. The potentiometer (often called a "pot") is Some rheostats. however, arc so construeted a controlinstrumentusedforvaryingthe that the circuit inay be opened also. In general, a amount ofvoltageappliedtoanelectrical rheostathas two terminals. One terminalis device. The term "potentiometer" customarily connected to one end of the resistance element: refersto any adjustable resistor having three the other, tothe sliding contact. .\s seen in terminals, two of which are connected to the figure Q-12. the resistance element is circular in ends of the resistance element and the third to shape andis made of resistance wire wound the wipercontact.Thepotentiometer is around an insulating form that usually is of a illustratedinfigure 9-13. By positioning the ceramic material. The resistance is decreased by sliding contact, any desired voltage within the rotating the wiper toward terminal 1. range of the potentiometer may be selected and "fo test a rheostat. you first must disconnect used where needed. As a rule. potentiometers itfrom circuit. An ohmmeter is used to arc constructed to carry smaller currents than measure ti.resistance between terminals 1 and rheostats. 2 (refer to 1.H. 9-12). with the wiper rotated all Potentiometers are measured in much the the way to terminal 2. This action gives total s.une way as rheostats. When disconnected from resistance. Moving the wiper slowly back toward thecircuit,theymaybetestedwithan terminal 1 shows an ever-decreasing resistance ohmmeter by measuring fortotalresistance until a reading of zero is obtained. If a rcadh-,g between terminal- 1 and 2. Applying one lead to of maximum shows on the meter during thk terminal 3 and the other Icad to either terminal phase of rotating the wiper toward terminal 1. it I or2and moving thewiper resultsina means the %viper is not making proper contact at smoothly increasing or decreasing variationin that point. resist:nice.

152

5%7 Chapter 9TEST EQUIPMENT; TESTMETHODS; MAINTENANCE CAPACITORS The lower row of dots (readingfrom right to left) are brown, red, and red.The brown dot Many capacitors have their value printedon requires the addition of them, but some types one zero to the value use a color code system to 25, giving the result as 250 ppf.The red center indicate their value. The color codeused is the dot indicates that the actual capacitor same as that used for resistors, but the methods value may of marking the capacitors bc p-eater or smaller than the 250 ppfby plus or vary greatly. The minus 2 percent. The left reddot means it is a method used for fixed mica capacitorsis shown in figure 9-14. bypass or silver mica capacitor.Some mica capacitors have only three dots,indicating the firstand second significantfigures and the A black dot in theupper left corner signifies multiplier. Their tolerance is 20 that the capacitor hasa mica dielectric. The percent, and they have a 500-volt rating. Tryreading some of center dot in the upper row indicates thefirst the values of the mica capacitors significantfigure, andtheupper you see in rightdot electronic equipment when theyare exposed to indicates the second significantfigure of the view.Learning to read capacitor values capacitancevalueinmicromicrofarads is a matter of practice, much like readingresistor The right dot in the lowerrow indicates the vahies. decimal multiplier that determinesthe number of zeros to be added to theright of the two Electrolytic Capacitors significant figures. The center dot(lower row) specifies the tolerance, which isthe possible deviation of the actual capacitor value Electrolytic capacitors are used wherea large from that amount of capacitance is required. Asthe name given by its dot markings. The left(lot on the implies,electrolyticcapacitorscontainan lower row deals with temperaturecoefficients electrolyte. This electrolyte and applications. can be in the form of either a liquid (wetelectrolytic capacitor) or a paste(dryelectrolyticcapacitor).Wet By way of explanation,a capacitor with electrolytic capacitors LIpper-row dots colored black, red, and are no longer in popular ilreen use due to the care needed to prevent spillingof "reading from left toright, :).ccording to the the electrolyte. iirectionalindicator)wouldmean a mica ;apacitor with the significant figures Dry electrolytic capacitors consistessentially 2 and 5. of two metal plates between whichis placed the

CAPACITANCE BLACK DOT IDENTIFIES MICA CAPACITOR DIRECTIONAL INDICATORS COLOR TOLERANCE CHARACTER- SIGNIFICANT DECIMAL ISTIC FIGURE MULTIPLIER SIGNIFICANT FIGURES OF . BLACK 0 CAPACITANCE 1 20 PERCENT 2ND A IN BROWN 1 f 10 B CHARACTERISTIC RED 2 100 2 PERCENT C CAPACITANCE TOLERANCE DECIMAL MULTIPLIER ORANGE 3 1,000 D YELLOW 4 CHARACT ERISTICS E GREEN 5 A - ORDINARY MICA BYPASS F BLUE 6 B SAME AS A-LOW LOSS CASE G VIOLET 7 C - BYPASS OR SILVER MICA (200PARTS- MILLION,C) GRAY 8 0 - SILVER MICA (* SOO PARTS MILLION-C) WHITE 9 E - SILVER MICA (0 TO .100 PARTSMILLION, C) GOLD 0.1 5 PERCENT F - SILVER MICA (0 TO50 PARTSMILLION,C) SILVER 0.01 10 PERCENT G - SILVER MICA (0 TO -50 PARTSMILLION.C)

20.376 Figure 9-14.Color code for fixed micacapacitors.

153 158 INTRODUCTION TO SONAR

dielectricalabsorption. Current leakageisof ALUMINUM FOIL considerableimportance,especially in electrolyticcapacitors.The measurement of capacitance is very simple; however, you must make the important decision of whether to reject or continue to use a certain capacitor alter PAPER ithas been tested. A common test equipment used for testing capacitors, the -Z.M-11A/U, is PAPER AND OXIDE FILM shown in figure 9-16. ELECTROLYTE

MAINTENANCE

Anypieceofmachineryorprecision equipment requires some type of care to keep it runningefficiently.Properupkeepofan automobile, for example, includes charwing the oil at certain mileage intervals. The windshield must be kept clean; headlights and brakes must be adjusted now and then; and an occasional enginetuneupmust be obtained.Sonar 236.216 equipment also requires periodic upkeep, but in Figure 9-15.Construction of an electrolytic more detail and at more regular intervals than capacitor. does anautomobile. Aboard your shipor submarine,youwillassistincarrying out scheduled maintenance on the equipment to electrolyte. In most cases the capacitor is housed which you aie assigned. in a cylindrical aluminum container which acts Various publications are available to assist as the negative terminal of the capacitor (fig. you in carrying out a maintenancc program. The 9-15). The positive terminal (or terminals if the manufacturer's technical manual for each piece capacitor is of the multisection type) is in the of equipment is an invaluable aid. These books form of alug on the bottom end of the describethe components or the equipment, container. The size and voltage rating of the operating standards, and required maintenance. capacitor is generally printed on the side of the OtherpublicationsincludetheNAVSEA ail!rninum case. Technical Manualand Electronic Information Capacitancemeasurements areusually Bulletins (EIBs). accomplishedbyeithera bridge-typeor a reactance-type capacitance meter. For accuracy, the former equipmentis comparable tothe TYPES OF MAINTENANCE resistance bridge, and the latter instrument is comparabletotheohmmeter.Capacitance Maintenance is divided into three categories, tolerances vary even more widely than resistance according to complexity and purpose. The three tolerances, being dependent upon the type of typesofmaintenanceare operational, capacitor, the value of the capacitance, and the preventive, and corrective. voltage rating. The results of capacitance tests At first glance it may seem that preventive mustbeevaluatedtodetermine whether a and operational maintenance are synonymous, particular capacitor will fulfill the requirements but there is a good deal pf difference between of the circuit in which itis used. The power the two. Operational maintenance is confined to factor of a capacitor is important because it is an tasks that can be performed by an operator indication of the various losses attributable to while heis on watch, and usuallyisfurther thedielectric,suchascurrentleakage and confined to one component, such as the sonar

154 1 5 9 Chapter 9 --TEST EQUIPMENT; TEST METHODS;MAINTENANCE

FUNCTION SWITCH

VOLTAGE CONTROL

5000M C CP46 10000

CAP DUAL CAP OSCILLATOR OUAL toADJUST FUNCTION

BALANCE INDICATOR RANGE CALIBRATE INS TEST

OSCILLATOR METER

QUALITY TEST

MULTIPLY RANGE POWER SETTING BY

1.68 Figure 9-16.Capacitance-inductance-resistance bridge ZM-11A/U.

onsole. Preventive maintenance is a systematic Operational Maintenance )rogram covering the entire sonar system and .equires several men to carry out. Operational maintenance is the elementary TheNaiy'soperationalandpreventive upkeep performed by the operator to keep his naintenanceprogramformerlywascalled equipmentingood operatingcondition.It )0MSEE. Ships and stations today, however. consistsmainly or proper operationofthe itilize a program known as the Standard Navy equipment,suchasstarting,stopping, 4aintenance and Material Management Systc:n. calibrating, and manipulating controls inthe nore familiarly called the 3-M System, which prescribedmanner.Attimes,operational be discussed later in the chapter. maintenance mayalsoincludeinspection,

1 55 130 INTRODUCTION To SONAR

cleaning, and lubricationof equipment, and and operating conditions may required cleanim replacement of minor parts, such as indicator more often. Overheating dueto cloggedair lamps. filtersoftenisa prime cause of equipment failure. Neglect in cleaning filters is, therefore Preventive Maintenance inexcusable. Gene rat ors must be given a careful Preventivemaintenance is intende(l to cleanlinesscheckwhiletheequipment is forestallequipmentfailure.Besidestesting, inoperative. Brushes and commutators should be discussedpreviously,thischapter comprises cleaned frequently. Be careful not to blow or inspection, cleaning, and lubrication. If' no high brush carbon dust and other foreign matter into degree of' technical skill or internal alignment is thewindingsorbearings.Whencleaning required, it also includes minor adjustments and generators, ensure that the brushes slide freely in replacement of minor deteriorated parts which, their holder and exert proper pressure on the ifleftuncorrected, mightlead to equipment slipring or commutator surface. malfunction or part failure. LUBRICATIONFlectronic gear has many INSPECTION.Allelectronicequipment partssuch as motors,hoists,gears,and should be inspected daily for such defects as springsthat requireregularlubrication. The brokenmeter glasses,loosecontrolknobs, manufacturer'stechnicalmanualshouldbe burned-outindicatorlights,loosecable followed toascertain where, how often, and connections, and the many small items that may how much lubricationis needed. Use caution be checked with or without the equipment when lubricating thepartsof' any piece of actually being energized. On units that utilize equipment, and follow the instructions in the ventilationfor cooling, the intake and outlet bookpertainingtotheindividualtypeof areas should be inspected to see that they are equipment. Too much lubrication can be just as free of obstructions. harmful as too little. Manyitemsshouldbeinspecteddaily, weekly, and monthly to help maintain the equipmentinserviceable condition.In sonic Corrective Maintenance instances these routine checks include electrical measurementstocheekindividualunitsfor Corrective maintenance, another name for malfunctioningcircuitry.Technicalmanuals repair, is necessary only after equipment failure. furnished by the manufacturer include lists of Co rr cc fivemain tenanceusually calls for checks to be conducted at regular intervals and replacement of internal parts or alignment of the desired reading or measurement required for electroniccomponentsrequiringtechnically peak performance of the specific equipment. trainedpersonnel.Someofthisworkis performed by operating personnel while assisting CLEANING.Cleaning is an important part the technician. As you advance in rate, you will of preventive maintenance. External surfaces of perform more highly technical maintenance on electronicunits andthe surrounding spaces your Own. should be cleaneddaily. This dailyroutine reduces the amount of dirt and dust that enters MAINTENANCE AND the equipment through circulating air blower MATERIAL MANAGEMENT SYSTEM intakes. Some dust and dirt naturally will work their way in: hence, the interiors of units should Reliability of electronic equ:pment depends be cleaned carefully, at least once a week, with a on the quality of the preventive and operational ,r)ft cloth. If possible, a vacuum cleaner should maintenance received bythe equipment. As used.Avoidusingblowers,bellows,or equipmentbecomesmore complex,the a.aning m)lvents, because they tend to push or maintenance problem becomes ever greater. wash dirt into inaccessible corners. Air filters Inthepast, many programs evolved that should be cleaned at least once a week. Climate often wereuncoordinatedandsometimes

156 Chapter 9TEST EQUIPMENT; TEST METHODS; MAINTENANCE

unworkable.Thelackofwell-trained Inestablishingminimumequipment technicians, together with the large number of main tenancerequirements,theNAVSEA reports required by some programs, seriously TechnicalManual,manufacturers'technical hampered the maintenance effort. Overloaded manuals, and other applicable publications are systemscommands,moreover,couldnut reviewedcritically.Ifplannedmaintenance properly correlate the mass of information in requirements are found to beunrealisticor the reports. unclear, they are modified or completely revised To alleviate these conditions, the Standard before incorporation into the PMS. Navy Maintenance and Material Management Itis possible that the planned maintenance M)Systemwcsimplemented.The3-M specifiedinthe PMS may differ from that S),stem replaces all othec maintenance programs. prescribed in other documents. Shouldsome It prescribes standard maintenance procedures, variancebecomeapparent,rememberthat, provides .a feedback report system that enables insofar as preventive maintenance is concerned, the progxam to be updated,'and corrects errors the PMS supersedes and takes precedence over and deficiencies. ex'ingrequirementssetforthinvarious Procedures for managing and reporting the te,.anical publications. maintenance progxam are contained in Ship's Maintenance and Alaterial Management ($-M) PLANNED MAINTENANCE SUBSYSTEM Manual,OPNAVINST 4790.4. MANUAL.A masterPlannedMaintenance' Subsystem Manual(OPNAV 43P1) is tailored to Basic elements of the 3-M System are the eachship. Planned Maintenance Subsystem (PMS) and the Itcontainsminimumplanned Maintenance maintenance requirements for each maintainable DataCollectionSubsystem component (MDCS). The PMS provides a uniform system of installedinthatparticularship. planned Normally,appropriatesections(engineering, preventive maintenance. The MDCS electronics, weapons, etc.) of the master manual provides a meansofcollectim;necessart; arekeptintheofficeofthedepartment maintenance and supply data, in a form suitable concerned. for machine processing. A man-hour accounting Respectivesectionsareused by elonartment heads in planning and scheduling all system alsois aboard repair ships and tenders in conjun,:tion with the MDCS. As a itenance requirements in their departments. third class petty officer, you will be concerned -The departmental PMS manual containsa with the Planned Maintenance Subsystem and section for each division or maintenancegroup certainportionsoftheMaintenanceData withina department. Each divisional section Collection SubsystenThe degree of equipment includes a table of contents and a maintenance readiness, effectiveness. :Ind 'ability depends index pan (MIP) for each system, sub3ystem, or on howwell perfnrmtherequired component. Applicableportions of the PMS maintenance. manual are kept in the working space for the equipmenttowhichtheypertain.These portionsserveasareadyreferencetothe Planned Maintenance Subsystem requiredplannedmaintenance. Each MIP containsabrief description of maintenance Preventivemainienance,whenproperly requirements and the frequency with which they carried out, reduces casualties and associated are to be effected. costs and equipment downtime, required for The frequency code is: Ddaily. Wweekly, major repairs. The PMS is designed to simplify M monthly,Qquarterly,Ssemiannually, maintenance procedures (insofar as possible) by .Aannually. Coverhaul cycle, and Rsituation defining the maintenance required, scheduling requirement. Frequency codes for daily, weekly, itsperformance,describingthetoolsand monthly.quarterly,semiannual,andannual methods tobeused, and providing for the plannedmaintenanceactionsare de tec ti onandpreventionofimpending self-explanatory.Code C designatescertain casualties. planned maintenance actions performed ina

162 157 INTRODUCTION TO SONAR

AMIN:MEW 51!;11 IN.4 1111 COSPI'ONI NI 11111111W:1. IIIJIILICAIIONS DAIL l Juno 19 (I

Main Circulating Pump

C.^0 I,11'. I lit NANCI 5115)5 SM. 411111 MU &TO . III IN IN w))1C). Ill(I Ill.1.0,5151)

syscomlimnc RELATED MAINTENANCE REQUIREMENT SKILL MAN CONTROLNO. DICITY MAINTE CODE LEVEL HOURS 84 5078W 1. Sample and inspect lube oil. W-I RM3 0.5 N011e Lubricate the speed limiting governor. Turn pump several revolutions by hand;if steam is available, turn by steam. 665075m 1. Test speed limiting governor. 1-I-1 9M1 0.2 Non,' RN 0.2

2575980 1. Clean pump and renew oil. 0-1 2-121 I 0 . 1 None '. Clean lube oil filter. RN 1.5 68P778Q Test spring-loaded cxl, ,ius tvalve Q-2 2-12-12 0.2 by steam. FN 0.2 0 A44830 1. Inspect reduction gears. 0-1 mrn 1) .5 None 0 654075 1. Renew stuffing box packing. 0-4 MM) 1.0 None 84 50R2A 1. Souud and tighten foundation 5-1 92-13 1.0 None bolts. 2. Inspect and clean steam strainer.

85 C 1. 5083 Inspect internal water lubricated C-1 2-011 12.0 Q..4 bearing and journal for condi- 21'N 24.0 tion. Measure bearing and pro- peller clearances. 95D045 C 1. Inspect carbon packing for wear. (- 1-012 2.0 N0nu RN 2.0

165510C 1. Clean,11-1!;pect, and preserve I C-3 2-12-12 1.0 C-2 exterior of turbine casing. FN 1.0

MAINEF ANCE INDEX PAGE SYSCOM AWCONTHOLNUMBER OPNAV FORM 4/00 3 IAI (REV 4 II) F-5/76-68

98.176 Figure 9-17.Example of a hull mechanical or electrical equipment MIP.

158 Chapter 9---TEST EQUIPMENT; TEST MIM-IODS; MAINTENANCE

specifiedquarter(i.e.,once)(luringthe required, and the specific quarter in which the operational cycle between shipyard overhauls. semiannual, annual, and overhaul cycle planned Code R identifies planned maintenance actions maintenance actions are to be performed. A thataretobeperformedbeforegetting cycle schedule also lists quarterly and situation underway, after a specified number of hours of requirement planned maintenance actions that operation, or to meet other requirements that must be scheduled, as well as monthly planned arise only during specific situations. maintenance requirement. Figure 9-17 shows atypical maintenance Cycle schedules are utilized by department index page. Information entered on the MIP heads, in conjunction with their division officers includesthe system or component, ashort and leading petty officers, to prepare quarterly description of each maintenance requirement, plannedmaintenance schedules. A quarterly maintenance frequency code plus a consecutive schedule is displayed in a holder, known as the numberstartingwithnumeral 1 foreach maintenancecontrolboard, adjacenttothe frequency code assigned, rate(s) recommended cycle schedule to which it pertains. A quarterly toperformthemaintenance,averagetime schedule givesavisualdisplay of the ship's requiredtoperformthemaintenance, and e m ploy men t s c hedule andtheplanned relatedmaintenancerequirements. Related maintenancetobeperformedduringthat maintenancerepresentsadditionalplanned particular quarter. A quarterly schedule has 13 maintenance that can be cornpleted before, in columns, 1 for each week in the quarter, for conjunctionwith,orimmediatelyafter a scheduling maintenance throughout a 3-month scheduled maintenance. period. Shipboard application of the PMS varies At the end of each week, the leading petty slightly from one ship to another. Clarification is officerofadivision or maintenance group required, therefore, of information foundon updates the quarterly schedule by crossing out MIPs regarding rates recommended to perform (withan X) thepreventivemaintenance maintenance and the average time required for performed. If a planned maintenance action is thetask.Actually,maintenancetasksare not completed during the week itis scheduled, performed by personnel available and capable, the leading petty officer circles the actionon the regardless of the rate listed on the MW. As listed quarterly schedule. Uncompleted maintenance is on the MIP, average time required does not then rescheduled for another week within the consider time required to assemble necessary same quarter. tools and materials,to obtain permissionto secure equipment, nor to clean the area and put At the close of each quarter, the applicable away tools upon conclusion of a task. Always quarterly schedule is removed from its holder remember, however, that no maintenanceis and retained on board as a record of the planned complete until all tools and equipment are put maintenance completed. This record may be away and the area is cleaned. discarded at the beginning of the second quarter alter the next shipyard overhaul.

SCHEDULING PLANNED A quarterly schedule alsoisused bya MAINTENANCE.For eachdivisionor leadingpettyofficertoarrangea weekly maintenancegroup,a cycleschedulethat planned maintenance schedule for posting inan provides a visual display of planned maintenance appropriate workspace. The weekly schedule of requirements (based on the operational cycle of planned maintenance should not he considered theshipbetweenshipyardoverhauls) is as the total of all work for a given week. This exhibitedinthedepartmentaloffice. weekly work covers only scheduled planned Information supplied on a cycle schedule for maintenance and is in addition to other routine any particular division or maintenance group work, upkeep, and corrective maintenance to be includes the MIP number from the PMS manual. accomplished. The weekly schedule provides a a listing of all equipment within that particular listofcomponents in theworkingarea, groupforwhichplannedmaintenance is appropriate page number of the PMS manual, 159 INTRODUCTION TO SONAR

and spaces for the leading PO to use in assigning pla nnedma intenancetaskstospecified personnel.Dailyandweeklyplanned maintenanceactionsarepreprinted onthe 5,51,S1 r,LOVE forms, and the other maintenance actions are t written in by the leading PO as required. When the leading PO is assured that a maintenance 41 NAT, task is completed,he crossesoutthe maintenance requirement number on the weekly schedule. If for some reason a task cannot be completed on the day scheduled, the leading pettyofficercirclesthemaintenance .tant14,1.41, InIhr

Ill' 4411i I requirement number and reschedulesitfor anotherday.Currentstatusofscheduled 11 Pan, f/010.1., 11,1 itIl. maintenance is readily available by looking at the weekly scheJule. MAINTENANCE REQUIREMENT CA RD. A maintenancerequirementcard (MRC) is a 5 by 8 inch card on which a planned maintenancetaskisdefinedsufficientlyto enable assigned personnel to perform the task. (Seefig.9-18.) A master setof MRCs is maintained inthe departmental office. Cards applicableto the equipment for which Sonar Technicial:. are responsible are maintained in the workspace.Ifacardinthe workspace becomes lost or mutilated, a new cardmay be made from the master set and can be used until a feedback report is sent in and a new card I LArt obtain1. A maintenance requirement card is one of Amommsenoseil theprincipal components of the PMS with whichSonarTechniciansare concerned. SupposethatonaMondaymorningan 98.176 individual looks at the weekly schedule and Figure 9-18.--MRC card. finds that he is assigned the maintenance action identifiedasM-14.Theweeklyschedule indicates that this particular maintenance action This information is given to enable personnel to is listed on page S0-9 of the PMS manual. The be completely ready to perform all prescribed MRC thatdescribesthetaskassignedis main tenancebeforeactuallyworkingon identified by the number combination S0-9, equipment authorized. The procedure described M-14 in the upper right corner. In preparation MRC is standardized and is the best for performing the assigned task, MRC number kvov.1 method of performing that particular S0-9, M-14 is selected from the set of cards in task. For purposes of time conservation, any theworkspace.An MRCidentifieseach related maintenance requirement included on component; gives the rate and time required to the MRC should be done at the same timeor in p rformthemaintenance;givesa brief conjunction with the assined task. description of maintenance required; cites safety precautions to be observed: and lists tools, parts, FEEDBACK REPORT.A PMS feedback and materials rwded to accomplish the task. report, OPNAV FORM 4790/7B (fig. 9-19) is

160 165 Chapter 9TEST EQUIPMENT; TEST METHODS;MAINTENANCE

purpose of submitting a feedback report is to correctadiscrepancy,forexample,ona

Cq,'CM, OPSAt .1 PIO maintenance requirement card,besurethe SEE INSTRUCTIONS ON BACK OF GREEN PAGE discrepancy is clearly FR-OM ISH-IP NAME AND HULL NUMBE RI identifiedandthe 011 recommended changeis BROOKE (DEG-1) correct and readily Ll August1972 understood.Instructionsforpreparingthe

NAVY MAINTENANCE MANAGEMENT TIELD OFFICE IC...7w,, Al report are listed on the back of the form. ETYPE CoMMANDER IC.I.ge BI

SUBJFET, PL.Z;NED MAINTENANCE SUBSYSTEMFEEDBACK REPORT Maintenance Data S,c00 Sub SS`,c (.0,ontlM1k, C.. A, ,t) MOO Compensating System Collection Subsystem CO,r.OL ...+C F -37/1 -CB 08 8776 (1 1 DESCRIPTIOlyrOF The Maintenance Data Collection Subsystem CATEGINiv A c.STECOlIV is intended to provide ameans of recording ..11PIMRCIEGI. REPLACEMENT TECHNICAL maintenance actions in substantial detailso that Ej EQUIPMENT ADDITION 0 TYCOM ASSISTANCE avarietyof information may be collected 0 EQUIPMENT DELETION OTHER ISPec.NI 0 CHANGE TO EQUIPMENT concerningmaintenanceactionsand

REMARKS performance of equipment. In additionto the foregoing information, MDCS furnishes dataon Before testing setting on relief valve, ye need calibration steps for Leslie-liatic controller. This initialdiscoveryof a malfunction,how step in procedure is not contained on the present HRC. 11,s ship does not have any pub or Tecn Manual as to equipment malfunctioned, howmany man-hours the steps that should be taken in checking the Leslie- wereexpendedonitsrepair,equipment Katic controller fur accuracy. involved, repair parts and materials used, delays incurred, reasons for delay, and the technical speciality or work center that performedthe maintenance. Inrecording maintenanceactions, codes .671 must ,,AnTsAi,T "CAC E be used to convert informationtoa i-I. A.; language that can be read by automaticdata TYCOM 2CoNcuo processing machines. Codes are E1J ..1:ST'O-Z 0" listedin the CC equipment identification code (EIC) manual. kr jj1.1.-e-eL /r1 7 2- OPNAI., AlTO 71316 lE ACTION COPY POC,C Third class petty officers are required toprepare - numerous maintenance forms, using appropriate EICs. These forms are sent toa data processing center where coded information is punched onto 98.176 cards, which then are machine processed.to Figure 9-19.PMS feedback report. produce various reports for use in maintenance and material management. Reports coming from the autoMatic data desigiedforreporting any discrepancies or processing machines are accurate and useful only suggested improvements in the PMS as installed if information is entered clearly and correctlyon aboard ship. This report is to be filled out by the maintenance forms. All codes suppliedon the man who discovers a dis.7repancy or suggests an forms must therefore be accurate and clearly improvement. Itis sig1e,_1 by a designee of the written. commanding officer and is mailed via thetype The MDCS requires that coded entries be commander to an appropriate field office listed madeonOPNAV Form4790/2k,Ship's on the reverse side of the originator's copy of Maintenance Action Form. Detailed descriptions the form. and instructions for this formare contained in When submitting a feedback report, besorc Volum..'IIof the 3-NI manual, OPNAVINST it is idled OW completely and legibly. If the 4791.-7, .

161 CHAPTER 10

SECURITY

The security of the United States in general Thorough understanding of this chapter will not and of naval operations in particular depends provide full knowledge of all the finer points greatly upon the success attained in safeguarding concerning security, but it will provide you with classifiedinformation.Itisofparamount a good fundamental background upon which importance that everyone responsible for the security is built. security of classifiedinformationpreservea balanced and comrnonsense outlook toward the subject. PURPOSE OF As a Sonar Technician you will hear a great THE SECURITY PROGRAM deal about the security of classified material because you willhave access to and utilize The security program deals basically with classified information every day. For this reason, the safeguarding of' information that could, in all a c tivitiesbriefnewlyarrivedSonar the hands of unauthorized personnel, be used to Technicians in security and require them to sign the detriment of the United States. Classified a statement attesting to the fact that they have informationmaybecompromisedthrough receivedthebriefingandunderstandthe carelesstalk, improper handling, and various content. Further, as a part of each command's other ways. Some of the ways in which military security program, you will be required to read personnel may accidentallygiveawayvital and indicate your understanding of several of informationarediscussedinBasicMilitary t he mostimportantnational lawsand Requirements, NAVEDTRA 10054(current regulations related to security. series). Ma intainingthesecurityofclassified material, however, requires more than a briefing, a regulation, or a law. Security will only be as '3ECURITY PRINCIPLES effective as you make it; there is no one to The Department of Defense security formula whom you can transfer your responsibility for is based on the premise of circulation control; protectingthis information. The security of i.e., classified material is not an extra job: it is a basic the contro1 of dissemination of classified information.Accordingtothispolicy, part of your assignment just asisoperating clectronic equipment. You must be security knowledge or possession of classified defense conscious to the point that you automatically information is permitted only to persons whose exercise proper discretion official duties require access in the interest of in the discharge of promoting national defense and only if they are your duties and do not think of security of determined to be trustworthy. informationas something separate and apart from other matters. Inthis way, security of classified information becomes a natural element DEFINITIONS o: every task and not an additionally imposed burden. The following definitions are taken from Securityis more than a matter of being Department of the Nary Infnrmation Security careful:itrequires both study and practice. Program Regulation, OPNA VINST 5510.1 E.

162 167 Chapter 10SECURITY

ACCESS informationasTopSecret,Secret,or Confidential. Theabilityandopportunitytoobtain 2.Determines that official information is in knowledgeorpossessionofclassified substance the same as information known by information. him to be already classified by the government as Top Secret,Secret,or Confidential and ALIEN designates it accord: n Any person not a citizen or a national of the United States. CLEARANCE

CLASSIFICATION Anadministrativedetermination by competent authority that an individual is eligible The determination that official information for access to classifiA information ofa specific classification cat..)1y. requires, in the interest of national security,a specificdegreeofprotectionagainst unauthorizeddisclosure,coupledwith a COW TENT AUTHORITY designation signifying that such a determination COMMANDING OFFICER has been made. For the purposes of this chapter, theterms CLASSIFICATION GUIDE "competentauthority"and"commanding officer"aresynonymous. Thesetermsare An instruction indicating the classification, intended to include "commander," "officer in downgrading, and declassification guidance that charge,""navalrepresentative,""director," may be assigned to subjects within a specific "inspector," and any other title assigned toan area of defense activity. individual, military or civilian, who, through command status,position, or administrative CLASSIFIED INFORMATION jurisdiction, is qualified to assume responsibility and to render a decision with regard toa specific Officialinformationwhichhasbeen question under consideration. determined to require, in the interest of national sec uri t y , protectionagainstunauthorized COMPROMISE disclosure and which has been so designated. Theknownorsuspectedexposureof CLASSIFIED MATERIAL classifiedinformationormaterialtoan unauthorized person. Any matter,document,product, or Compromise, when evaluated for reporting substance on or in which classified information purposes, shall be described as follows: is recorded or embodied. I.Confirmedcompromise isconsidered CLASSIFIER confirmed when conclusive evidence exists that classified material was compromised. Anindividual who doeseither of the 2.Suspectedcompromise is suspected following: whenevidenceexistsbeyondareasonable doubtthat classified material hasbeen 1.Determine that official information, not subjected to compromise. known by him to be already classified, currently 3.Re mote co mpromise is considered requires, in the interest of national security,a remote when, after the conduct of an initial specificdegreeofprotectionagainst inquiry, there exists strong evidence indicating u na utho rizeddisclosureand,havingthe there was minimal risk of the material getting authoritytodo so,designatesthatofficial into the public domain or minimal risk that the

163 INTRODUCTION TO SONAR

circumstances of the unauthorized disclosure MARKING could reasonably be expected to damage the national security. Thy physical act of indicating on classified material the assigned classification, changes in CUSTODIAN classification, downgrading and declassification instructions, and any limitations on the use An individual who has possession of or is thereof. otherwise charged with the responsibility for safeguardingandaccountingforclassified NEED m KNOW information. The necessity for access to, or knowledge or DECLASSIFICATION possession of classified information to carry out Thedeterminationthatclassified official military or other governmental duties. information no longer requires, in the interest of Responsibilityfordeterminingwhethera nationalsecurity,anydegreeof protection person's duties require that he possess or have against unauthorized disclosure, coupled with a access to classified information and whether he removal or cancellation of theclassification isauthorizedtoreceiveitrestsupon the designation. possessor of the classified information and not upon the prospective recipient. DOCUMENT RESTRICTED DATA Any recorded information, regardless of its physicalformorcharacteristics,including, All data (information) covering (1) design, without limitation, written or printed material; manufacture, or utilization of atomic weapons; dataprocessing cards and tapes; maps and (2) the production of special nuclear material; or charts; paintings; drawings; engravings; sketches; (3) the use of special nuclear material in the working notes and papers; reproductions of such production of energy, but not to include data things by any means or process; and sounci. declassifiedor removed from the Restricted voice, or electronic recordings in any form. Data category pursuant to Section 142 of the Atomic Energy Act. (See SectionI1 y, Atomic DOWNGRADE Energy. Actof1954, asamended,and "Formerly Restricted Data.") To determinethatclassifiedinformation requires, in the interest of national security, a SECURITY lower degree of protection against unauthorized disclosure than currently provided, coupled with A protectedconditionofclassified a changing of the classification designation to informationwhichpreventsunauthorized reflect such lower degree. persons from obtaining information of direct or indirect military value. This condition results FORMERLY RESTRICTED DATA from the establishment and maintenance of protective measures which ensure a state of Information removed from the Restricted inviolability from hostile acts or influence. Data category upon determination jointly by the Atomic Energy Commission and Department of UPGRADE Defense that such information relates primarily to the military utilization of atomic weapons Todeterminethatcertain classified and that such information can be adequately information requires, in the interest of national safeguarded asclassified defense information. security, a higher degree of protection against Such information is, however, treated the same unauthorized disclosure than currently provided, asRestrictedDatafor purposes of foreign coupled with a changing of the classification dissemination. designation to reflect such higher degree. 169 164 Chapter 10SECURITY

CLASSIFICATIONATEGORIES unautho rizeddisclosureofwhichcould reasonably be expected to cause damage to the Official information_11:Lt requires protection National security, such as- in the interest of national defense is placed ir.to 1. Operationalandbattlereportsthat one of three categories: Top Secret, Secret, or contain information of value to the enemy. Confidential.Followingareexamplesand 2. Intelligence reports. defin: Lions or each category. 3. Militaryradiofrequency and callsign allocations that are especially important or are TOP SECRET changed frequently for security reasons. 4. De v i ces andmaterialrelatingto The Top Secret classificationis limited to communication security. defense information or material requiring the 5. Information that reveals strength of our highest degree of protect:on. It is applied only land, air, or naval forces in the United States and to information or material the defense aspec.t of overseas areas, identity or composition of units, whichisparamount, andtheunauthorized ordetailedinformation relatimztotheir disclosureofwhichcouldreasonably be equipment. expected to cause EXCEPTIONALLY GRAVE 6. Documentsandmanualscontaining DAMAGE to the Nation, such as- techni ca 1information used fortraining, andinspectionofclassified the maintenance, 1.A war, an armed attack against munitions of war. UnitedStatesor herallies,orabreakin 7. Operational and tactical doctrine. diplomaticrelationsthatwould affectthe 8. Research, development, production, and defense of the United States. procurement of munitions of war. 2.The unauthorized disclosure of military 9. Mobilization plans. or defenseplans,intelligence operations, or 10. Personnelsecurityinvestigations Lind scientific or technolo0.cal developments vital to other investigations, such as courts of inquiry, the national defense. which require protection against unauthorized disslosure. SECRET 11. Matters and documents of a personal or disciplinary nature which, if disclosed, could be The Secret classification is limited to defense prejudicial to the discipline and morale of the informationormaterialtheunauthorized armed forces. couldreasonably be disclosureofwhich 12. Documents usedinconnectionwith expected to cause SERIOUS DAMAGE to the procurement.selection,orpromotionof Nation, such as military personnel, the disclosure of which could violate the inteuity of the competitive system. I.Jeopardizingtheinternational relationships of the United States. NOTE: Officialinformation of the type 2.Endangeringtheeffectivenessofa described in paragraphs 10, 11, and 12 above is program or policy of vital importance to the classified Confidcntiai oniy if its unauthorized national defense. disclosure could be orejudicial to the defense 3.Compromising importantmilitaryor interests of the Nati,m. If such information does defenseplans,orscientificdevelopments notrelatestrictlytodefense,itmustbe important to national defense. safeguarded byothermeansthan the 4.Revealingimportantintelligence Confidential classification. operations.

CONFIDENTIAL ACCOUNTABILITY

The use of the Confidential classification is Acontinuous chain of receiptsfor Top limited to defense information or material the Secretmaterialismaintained.Inaddition. a

165 1' 0 INTRODUCTION TO SONAR disclosure recordformisattached to each An exclusion document that circulates within areaisfully enclosed bya a command or perimeter barrier of solid activity, and eachperson having knowledge of constructici. Exits its contents signs the form. and entrances are guarded,or secured and alarm protected; and only thosepersons whose duties Each command establishesadministrative require proceduresforrecordingSecret access and who possess appropriate material security clearancesare authorized to enter. originatedandreceived,andmaintains a receipting system for Secretmatter distributed or routed within the command. Limited Area Each command alsomaintains a system that ensures accountabilityforallConfidential A limitedareais material originated or received. oneinwhichthe uncontrolled movement ofpersonnel permits accesstotheclassified informationtherein. Within the area,access may be prevented by PHYSICAL SECURITY escort and other internal controls. The area is enclosed by Physical security has to do a clearly defined with safeguarding perimeter barrier. Entrancesand exits are either classifiedinformation byphysical means.It guarded,controlled by attendants includesthedesignationof to check securityareas, personaliden tification,orunderalarm stowage, custody, accountability,transmission, protection. dissemination,andultimatedispositionor Operating and maintenance destruction.Inother personnel who words,herewe are require freedom ofmovement within a limited concernedwithmethodsof preventing area must have a proper securityclearance. The unauthorized persons fromobtaining physical commanding officer custody of classified material. may, however, authorize entrance of persons who donot have clearances. In such instances,escorts or attendants, and SECURITY AREAS other security precautionsmust beusedto prevent access to classifiedinformation located within the area. Sonar isdesignated as a limited Spacescontainingclassifiedmatterare area. known assecurityareas. These security (or sensitive) areas have varyingdegrees of security interest, dependingupon the purpose and the Controlled Area nature of the work and informationor materials concerned.Consequently,therestrictions, A controlled area does controls, and protective not contain classified measures required vary information. It serves asa buffer zone to provide according to the degree ofsecurity importance. geater administrative control To nie.F.q different levels of and protection for security sensitivity, thelimitedorexclusionareas.Thus, herth :.three types of securityareas; all areas passageways or spaces surrounding are cleariy marked by signs reading or adjacent "SECURITY to limited or exclusionareas may be designated A REAKEEP OUT.AUTHORIZED controlled areas. RSONN EL ONLY." Controlledareasrequirepersonnel identification and controlsystems adequate to Exclusion Area limit admittance to thosehaving bona fide need for access to thearea.

Spacesrequiringthestrictestcontrol of STOWAGE accessaredesignatedexclusionareas. They contain classified matter ofsuch nature that, for Stowage refers all tothe manner inwhich practical purposes, admittanceto the area classifiedmaterialis permits access to the material. protectedbyphysical and/ormechanicalmeans.Thedegreeof 166 I 'I Chapter 10SECURITY protectionnecessarydependsonthe mistakenlybeen placedinthe wastebaskets. classification,quantity,andscopeofthe Classified trash must be placed in burn bags and material. thebagsmustbeproperlystoweduntil A numerical evaluation system has been destroyed according to your command's policy. developedfordeterminingtherelationship Vaults, safes, or lockers used for stowage of betweenthesecurityinterestandlevelof classified matter must always be kept locked protection required. The system is outlined in when not under the supervison of authorized chapter5 and appendix H of OPNAVINST personnel.Alwaysrotatethedialofall 5510.1 E. combination locks at least four complete turns The keys or combinations tosafes and when securing safes, files, and cabinets. If the lockers containing classified material arc made dialisonly given a quick twist,it may be available only to persons whose duties require possible to open the lock merely by turning the access to them. The keys or eombinations must dial in the opposite direction. Always make sure be changed at least every 12 months. They also that all drawers of safes and file ca'-ets are mustbechanged when anypersonhaving heldfirmlyinthe locked position.rior to knowledge of themistransferred from the removal of any furniture from a security area, organization,andwhenthe keysor always check closely for classified material in combinationsaresuspectedofbeing hidden areas of each desk, safe, or cabinet. compromised. Anytimeyoufindasafeorcabinet containingclassifiedmaterialunlocked and SECURITY CLEARANCES umqtended by assignedpersons,be sure to report the condition immediately to the watch PERSONNEL CONTROL officer. Do not touch the container or contents, but guard them until the officer arrives. The An important element of' physical security is watch officer thenissumes responsibility for personnel control. No person is permitted access such further ictions as locking the safe, recalling to classifil material unless he previously has theresponsiblepersons,andreportingthe beengranied asecurityclearancebyhis security violation to the commanding officer. commandingofficer.Everyclearance above Confidential is based on a national agency check PROPER HANDLING ( NAC), a background investigation (B1), or both. An NAC consists of the investigation of files Each individualinsonar must take every and records of a number of agencies including precautiontopreventintentionalor casual theFBI. ONI, and BUPERS. A background access to classified information by unauthorized investigation, which includes an NAC, inquires persons. When classifiedpublicationsare into the loyalty, integrity, and reputation of the removed from storagefor working purposes, person being investigated. they must be covered or placed face down when Apersonnelsecurityclearance isan not in use. If sonar must be vacated, all classified administrative determination that an individual material mustbe properly protected. Rough is eligible, from a security standpoint, for access drafts, carbon paper, worksheets, and similar to classified information of the same or lower items containing classified information should categoryastheclearancebeing granted. A be placed in a burn bag after each has served its certificateofclearancedoesnotinitself purpose. constituteauthorityforaccesstoclassified At the end of each watch,allclassified information.Itismerelyadetermination of material that must be passed from watch to eligibilityfor access. Classified information is watchisinventoried properly and custody is made available to appropriately cleared persons transferredto the relieving watch officer and only whenitisnecessaryinthe interest ot watch supervisor.Allother classified matter national defense, when the individual requires must belockedup. Wastebaskets should be the information to carry out his assigned duties, checkedtoensurenoclassifiedtrashhas when thereisno other source of the s5rne 172 167 INTRODUCTION TO SONAR classifiedinformationavailableto him, and when he is capable both 9. Participationintheactivitiesof an physically and mentally organization, with knowledge of providing the degxeeof protection that the that it had been information requires. infiltrated by members ofsubversive groups. 1 O. Sympatheticinterest intotalitarian, The following isa list of personal acts ot' Fascist, varyingde,grees Communist,orsimilarsubversive ofseriousnesswhich, it' movements. committed in the pastor present, can cause the 11. Currently denialor revocation of apersonal security maintaining a close, clearance. continuing association witha person who has engaged in activitiesor associations of the types referred to above. I. Commission ofany act of sabotage, espionage, treason, 12. Theuncovering of anyfacts which or sedition; conspiring with furnish reason to believe or aiding or abetting another tocommit or that the individual may attemptto be subjected to coercion,influence, or pressure commit anyactof sabotage, which may cause him espionage, treason,or sedition. to act contrary to the best interests of national security. 2. Establishmentorcontinuationof a 13. Willful violationor disregard of security sympathetic association witha saboteur, spy, regulations. traitor,seditionist,anarchist,revolutionist, espionage or other secret 14. Intentionalunauthorized, disclosure of agent or representative classified information to of a foreign nation,or any representathe of any person. a 15. A nycriminal,in famous, foreign nation whose interestsare inimical to the dishonest, illterests of the United States. immoral, or notoriouslydisgraceful conduct-, habitualuse 3. Advocacy ot'use of force of violence to of intoxicantsto excess; drug overthrow the government of addiction; or sexual perversion. the United States, 16. Actsofareckless, or the alteration of the form ofgovernment of irresponsibleor the United States by wanton nature which indicatepoor judgment unconstitutional means. and instability. 4. Membershipinoraffiliationor 17. Any excessiveindebtedness, recurring sympathetic association withany foreign or financial difficulties, domestic organization,association, movement, unexplained affluence,or group,or combination of repetitive absences withoutleave. persons whichis 18. Al 1 o t herbehavior, totalitarian, Fascist, Communist,subversive, or activities,or which has adopted associations which tendto show that the person a policy of advocatingor is not reliable or trustworthy.. approving the commissionof acts of forceor violence to deny other 19. Anyillness,includinganymental' persons their rights under condition, of' a nature which, the Constitution of the UnitedStates. in the opinion of competentmedicalauthority,may 5. Actions whichservetheinterestsot' cause another significant defect in thejudgment or reliability governmentinpreferencetothe of the individual. interests of the United States. 6. Failureor refusaltosignaloyalty certificate,pleading protection ofthe Fifth COMPROMISE Amen' t or of Article 31 UniformCode of Mil;" or refusal to completely answer qu. No one in the Navy isauthorized to handle )ns co:.cained in required securityforms or pe:rsonal history statements. any classified material exceptthat required in 7. Any the performance of duty.All other personsare deliberatemisrepresentation, unauthorized, falsification, or omission ofmaterial fact. regardless of rank, duties,or 8. Participation clearance. intheactivitiesof an If organization established itisknown--or even suspectedthat as a "front" for an classifiedmaterialis organizationreferredtoabove, when one's lost or passed into the personal hands of some unauthorizedperson. the matter viewsweresympathetictothe is said to be compromised. subversive purposes of suchorganization. The seriousness of the compromise dependson the nature of' the 168 i Chapter 10SECURITY

materialandtheextenttowhichthe sometimesreveal militaryinformationof unauthorized person may divulge or make use of incalculable value. whathelearns.Neverfailtoreport a compromise that comes to your attention. Mail likewise is subject to interception by an enemy. Thefollowingtopicsmust notbe mentioned in personal correspondence: DISCIPLINARY ACTION I.Location, identity, or movement of ships FOR SECURITY VIOLATIONS or aircraft. Any person who is found to be responsible Forces, weapons, military installations, for the loss, unauthorized disclosure, or possible or plans of the United States or her compromise of classified information, and any allies. person who violates security regulations shall be promptly and adequately disciplined, regardless 3.Casualties to personnel or material by of rank or rate, or position. Disciplinary action enemy action. may includetrialbycourt-martial.Persons 4.Employment of any naval or military foundguiltyoflossof classifiedmaterial unit of the United States or her allies. through gross neglect may be fined $10,000 c - imprisoned for not more than 10 years or both. 5.Criticism of equipment or morale of the United States or her allies.

PERSONAL CENSORSHIP Pe rsonalcensorshipalsoextendsto telephone conversations. Telephone wires can be Personal censorship is the most difficult part tapped, and conversations can be overheard at the of security. Each individual, through indiscreet switchboard and other points along the circuit. or boastful conversation, personal letters, and Neverdiscussclassifiedinformationovera telephone. A guidetopersonal conductis ofclassifiedinformation in discussions presented at the end of this chapter. nonsecure spaces,iscapable of doing grave damage to the security of our country. Personal discussion of officialaffairs with families or friends, or even careless talk, while on duty in RESTRAINT ON REPRODUCTION thepresenceof personsnot authorizedto receive certain information,is dangerous and Those portions of documents and materials must be avoided. There is only one safe policy which contain Top Secret information shall not for you to follow when off dutydon't discuss bereproduced withouttheconsent of the classified matters with anyone, not even family originating activity or higher authority. All other or close friends. Usually the desire to impress classified material shall be reproduced sparingly inthe minimum number of copies; and any others with the importance of one's job is quite stated prohibition against reproduction shall be strong.Divulging classified informationis an strictlyobserved.Thefollowingrestrictive unwisewayoftryingtoimpress anyone, particularly when by doing so a man may be measures apply to reproduction equipment and endangering his country and many lives. to the reproduction of classified material: I.The number of copies of documents inpublic places is even more Loose talk containing classified information shall be kept to dangerous. Conversationinrestaurants, hotel lobbies, airports, elevators, taverns, and other a minimum to decrease the risk of compromise public places can be overheard easily. Foreign and reduce storage costs. agents are trained scientifically to collect from 2.Officials, by position title, authorized to suchconversationsparticlesofseemingly approve the reproduction of Top Secret and harmless information. Once pieced together and Secretmaterialshallbedesignated.These analyzed,these"innocent"bitsoftalk designatedofficialswillcarefullyreview the 174 169 INTRODUCTION TO SONAR need for reproductions with a view toward DISSEMINATION POLICY minimizing classified reproductionsconsistent with operational requirementsand reproduction Components shall establishprocedures for prohibitions imposed by the materialoriginator the or higher authority. disseminationofclassifiedmaterial originatedorreceivedby them, subjectto specific rules established by 3.Specific reproduction equipmentshall be higher authority and designatedfor by OPNAVINST 5510.1series. As afurther the reproduction of classified limit on dissemination, the material; reproduction of classifiedmaterial shall originating official or be restricted to equipment activity may prescribe specificrestrictions on a so designated. Rules, classified document tominimizehumanerrorinherent or on its text when security inthe considerations make them reproductionof classifiedmaterial,willbe necessary. posted on or near the designatedequipment. A General Guide 4.Appropriate warning notices prohibiting reproductionof classified materialshallbe Itis not possible to provide eachindividual postedonequipmentusedonlyforthe with a complete list of do's reproduction of unclassified material. and don'ts as far as security is concerned. Thereare, however, two rules of thumb which 5.Ifthe willusually helpin designated equipment involves answering the questions "Should1 do this?" or reproduction processes usineextremely sensitive "Should I say this?" reproduction paper, suchpaper shall be used and storedinamanner to preclude image 1. transfer of classified information. Could spies or traitorspossiblylearn anything from this? a.When thermal copy paper is usedto reproduce documentsupon which classified 2.Could this possibly help spiesor traitors information has been recorded, onlyType 1 verify something that theyalready have (back coated) thermalcopy paper shall be ideas about or have guessed? used. b. When slip sheetsare placed between If there is the slightestpossibility that the thediazoprocessfilmsheetsinthe answer to either of these two questionsmight be reproductionprocessofclassified "Yes," "Probably,"or even"Possibly," the information,theslipsheetsshouldbe action should not be takenor the statement handled as ciassified waste. shouldnotbemade. One of thepersonal restrictions that working withclassified material 6.All copiesofclassifieddocuments requires of an individual isthat conduct and reproduced for any purpose, includingthose speech must always be guarded.The goal of the incorporated in a workingpaper, are subject to security program is to trainmilitary and civilian the same controls prescribed forthe document personneltothepointthatwhenever and from which the reproduction is made. however a topiccomes up which has even the most remote bearing on classifiedinformation, 7.Samples, waste, oroverruns resulting the employees will automatically fromthe become alert, reproductionprocessshall be watchful, and on their guardagainst security safeguarded according to theclassification of the slips. informationinvolved andshall be destroyed The following list may be used promptly as classified waste. as a general guide to answering themany questions that may be asked concerning securityinformation. 8.When classified materialis reproduced, the reproduced material shall bemarked with the 1. You may disclose thecommand you classification and other special markings work for by simply stating which appear on theoriginalmaterial from that you work for which copies are reproduced. the Department of the Navyat the address to 1 r- which you are assigned. Usingutmost discretion, 170 Chapter 10SECURITY

you maygivetheofficialaddress of your restriction is imposeddependsuponthe command, your eneral job title, your uade and assignmentthatyouheld.Certainother salary, and length of service, if required. If any restrictionsareimposed onprivateoverseas further informationisdesired by persons or travel by the State Department. When leaving firms with whom you may be dealing, instruct your present assignment, you will be informed them orequest such information by letter as to what restrictions apply, if any. addressed to your commanding officer. 8. Therearealsosecurityrequirements 2. When replying to questions by anyone concerning vacation or business travel abroad. (including your immediate family), concernimz Your commanding officer will assure that you the nature of your assignment, you should state are given a defensive security briefing to alert that your work is classified and that the law you to be on guard against exploitation by prevents you from revealing the type of work in others whose interests may be inimical to those which you are engaged. of the United States, prior to travel under the 3. Caution your family nut to discuss your following conditions. assignment withothers. They should simply a. Traveltoorthrouh state that they do not know what your duties Communist-controlledcountriesforany are.Remember, the less your family knows purposes. about your job,theless likely they areto b.Attendanceatinternational, unwittinglyrevealinformationof valueto scientific,technical, engineering, or other foreiczn intelligence. professional meetings in any country outside 4. If a complete stranger is overly persistent the United States where it can be anticipated inquestionina you about your job, simply thatCommunist-controlled representatives inform him that you do not care to discuss the will participate or be in attendance. subjectfurther.Quiz him as tohis name, address, and purpose of hisinquiry. Fle will 9. Generallyspeaking,nothing maybe probably drop the subject. You may leave his written or said for public consumption about presence, if circumstances permit, or change the the status, mission, composition, organization, subject.Inallcases,reportthefacts and or function of the command that you are circumstances to your commanding officer. presently assignedtoortheresultsthatit 5. Classified matters may only be discussed, obtains. Of course, certain information may be outside your assigned ship or station, in other printed for public consumption, but only the secure government spaces and then only if itis commandingofficerorhis designated necessarytoeffectofficialbusiness.First representative may release such information. determine the clearance status of the other party 10. Upon learning of what appears to be a and his need to know in conjunction with that security violation by the press. radio, television, business. The information will be limited to that or any other means normally available to the which is necessary to carry on official business. public, bring it to the attention of your security 6. You may associate with non-citizens on officer or commanding officer. State the facts: a close social basis. However, any contact other what, when, where, how, and by whom. If itis thanofficialwithpersonnelfrom printed material, submit a copy or an actual Communist-controlledcountriesshould be clippingofthematerial.Include the reportedtoyourcommandingofficer identificationof theperiodical,thefiuthor, immediately. Meetingswithotherforeign and/or the photographer. nationals need not be reported. II. From time to time you may wonder why 7. There mayberestrictionsongoing you are required to be so security conscious overseas after leaving your present assignment, whenthenews media seems tohetelling either for a new assignment or privately. The everything. Thisisunderstandable. However, specific restrictions are dependent upon the type always remember that just because certain items of classified information to which you may have appear in periodicals, newspapers, or On the air, had access and the area of the world to which it doesnotnecessarilymeanthattheir you wishtogo.Thelengthof timethe publication was authorized nor does it mean

171 1 7 6 INTRODUCTION TO SONAR that the information is factual. Frequently, such information. Be ever mindful ofwhere you are, releases are the educated guesses of the author. even when you are Do not deny, affirm, talking to other Sonar or comment on such Technicians. Security informationcan only be material; it will only aid in establishingas fact discussed in sonar or the few other that which, before, was only suspected. secure spaces aboard ship. Discussion of securityinformation 12. When separated from the Navy,you is forbidden in any of the other must spaces aboard continueto besecurityconscious, ship, such as the mess hallor your berthing especially when applying fora job. During your compartment. job interview, you may state thatyou were assigned to a particular command,along with Theabovelistdoesnotcoverevery your general job title. Under no circumstances circumstancewhichmayarise.Should a mayyouincludeDepartmentofDefense situationarise whichisnot covered in this classified information. Itis recommended that. chapter, no statement should bemade. Report prior to your separation,you write a complete the situation to your superior andan appropriate jobdescriptionofyourdutiesand answer will be given for future guidance. responsibilities. Take your resumetoyour You alone are responsible forany violation division officer for his advice, assistance,and oFsecuritythat clearance. you maydeliberatelyor unintentionallycommit. You areurgedto become fully acquainted with the As a Sonar Technician contents of you will have access theDepartmentoftheNavyInformation to large amounts of classified material, which SecurityProgramRegulation, sometimes makes life aboard ship OPNAVINST very tedious. 5510.1E. Moreover, you must alwaysvigilantly The majority of your shipmatesdo not have guard against violating the trust which security clearances or even has been a need to know. You placed in you. To relax security,even for a can not. of course, give them any classified moment, may invite disaster.

177

172 APPENDIX I

GLOSSARY

ABSORPTION:Loss of energy that is turned BA THYTHERMOGRAPH: A devicethat into heat. automaticallyplots a graphshowing termperatureasafunction of depth when ACOUSTIC:Pertaining to sound or the study lowered into the sea. of sound. BEARING: The direction of an object from an ACTIVE SONAR: An apparatus that radiates observer, measured clockwise from a reference and receives information from returning echoes. point.

ADVANCE: Afterrudderisapplied,the BEARING DRIFT:Bearing cursor is trained distance continued along original course until on back and forth across the target to check for the the new course. bearing width, and the target is classified. The operator then places the cursor in the center of AFTERNOON EFFECT:The daytime heating the target pip. The cursor shows direction of of the surface water which results in a reduction sound reception. Its length indicates range when of sonar ranges usually in the afternoon. the cursor line is adjusted to touch the target echo. With the ship headed for the target on a AMBIENT NOISE: The naturally occurring steady course, and at a constant speed, with the noise in the sea and the noise resulting from cursor bisecting the echo, any change in target man'sactivitybut excluding self-noiseand bearing results from target movement. If the reverberation. target moves to the right, the operator must train his cursor to the right in order to remain on target, reporting "Bearing drift right." If the AOB (Angle on the Bow):The angle formed target moves to the left, he must train his cursor between an imaginary line drawn from a target's to the leftto remain on target, and reports stern through its bow and outward, and a second "Bearing drift left." line between the target and own ship. Angle is measured from 0000 to 180° both port and BOTTOM BOUNCE: Thatformof sound starboard. Clockwise down starboard side and transmissioninwhich sound rays strike the counterclockwise down port side. bottom, in deep water, at relatively steep angles, and are reflected toward the surface. ARRAY: A group of hydrophones arranged to provide the desired directional characteristics. CAVITATION: The formation of local cavities (bubbles) in a liquid as a result of the reduction ASROC: Antisubmarine rocket. of total pressure. This pressure reduction may result from a negative pressure produced by ASW (AntisubmarineWarfare): Operations rarefaction or from the reduction of pressure by conducted against submarines, their supporting hydrodynamic flow such as is produced by high forces and bases. speed movement of an underwater propeller.

173 178 INTRODUCTION TO SONAR CIC (Combat Information Center): The tactical DI VE RGENCE: Energy losscaused by command center of the ship. spreading in all directions. COMPRESSION: In wave motion, the forcing DOPPLER EFFECT:Ifthereisa togetherofthemedium's relative molecules.See movement betweena wavesource RAREFACTION. anda reflecting surface, the frequency of thewaves returning to the source will differ from thatused COUNTERMEASURES: Devicesand/or intheoriginalemission. Thisis known as techniques intended to impair the operational doppler effect. In active sonar sets, th:! effectof effectiveness of enemy activity. source movement is allowed for automatically and so the change in frequency indicates CRT: Cathode ray tube. relative movemen tofthereflectoralorqg the source/reflector line. CW (Continuous Wave): The on-off keyingof a carrier frequency of a transmitter in sucha way DYNAMIC TESTS:Dynamic tests are rn to as to form a code that can be translated intoa check the computer's generation of readable intelligence. bearing and rangeforspecifiedtime intervalsagainsta mathematical solution whoseanswer contains db (dB):Abbreviation for decibel. .2orrect amounts of change in quantities for like conditions. During the test, fixed values DECIBEL: A value are thatexpresses he assigned to relative motion ratesby manually comparisonofsoundsoftwodiffere;.. setting inputs to the relative motion intensities. This value is defined group. The as 10 tit=ie time system of the computer .is thenmoved, common logarithm of the ratio of the two sound either manually or by thz time intensities. motor, an amount equal to the test :nterval. Readingsare then taken to ensure correctness of the solution. DECK PLANE:The deck plane represents the level of the ship's gun mounts. (referencesto guns include similar weapons systems.) When the ECHO:That portion of the energy reflected to shipislevel, the horizontal and dec.planes the receiver from the target. coince, but when the ship rolls and pitches, the deck plane deviates from the horizontal.The ELECTROSTRICTIVE: stable element measures the amount of A mechanical angular deformation caused by the application ofan deviation and transmits the informationto the electric field. fire control system. The fire controlcomputer compensatesfordecktilt by computing a ESM (Electronic Warfare SupportMeasures): solution in the horizontal plane, then makes Concernselectronicemissionsand traiii and elevation corrections. What thesystem countermeasures. does, in effect, is bring the deck plane backto the horizontal. FATHOMETER: A direct reading device for DENSITY: The mass perunitvoiume. determining water depth by reflectingsonic or Example: salt water-30 parts/1000. ultrasonic waves from the ocean bottom. DIPPING SONAR: Usedby helicopters. F BM: FleetBallisticMissileSubmarine. Lowered from the helicopter for searching and (SSBN) retracted for flight. FCS.Fire Control System. DIRECT PATH:Sound waves that travel in direct paths at whatever angle they leftthe FIRE CONTROL: The technique fordelivering source. fire on a selected target.

174 1. 7 9 Appendix IGLOSSARY

FLOW NOiSE:The rit-7:A: producedciwater LAYER EFFECT: Partialprotectionfrom movement pastth,:'tran!,ducer,hydrophone echo ranging and listening detection wliee below array housing, or the htiof a moving ship or layer depth. submarine, or by t"e vrtical movement of a sonobuoy in the sea. MAD (Magnetic Anomalous Detectors):Equip- ment capable of detecting slightdistortions FREQUENCY:Rate of vibration of a sound in the earth's magnetic field. In the U.S. Navy, source. Determines the pitch of a sound. used exclusively by aircraft.

GRADIENT, NEGA IN nenthe M AG NE TO ST R I CTI VE(ION)PROCESS: temperature of the wa ses with depth, Changes in metal caused by being subjected toa it has a negative temper ient. magietic field. GRADIENT.POSI L: Whenthe M C: Shipboardannouncingand temperature of the water increases with depth, it intercommunications system circuit. has a positive temperature gradient. MDCS: MaintenanceDataCollection HERTZ: A unit of frequency equal to one Subsystem. cycle per second. mHz (Megahertz): Prefixdenoting106or HORIZONTAL PLANE: A horizontal plane is 1,000,000. tangent to the suirface of the earth. Visualize this condition by laying a playing card on an orange. MICROPASCAL: The standard unit of'measure The card represents the horizontal plane, the inallsonar computationsfor sonar sound orange symbolizes the earth, and the point of pressure level. Replaces the microbar. contactbetween thetwoisthepointof tangency. Every plane parallel to the horizontal M1P:Maintenance Index Page (3-.1 system). plane is likewise a horizontal plane. MRC: Maintenance Requirement Card (3-M HORIZONTAL RANGE: Range from own ship system). to target measured in the horizontal plane. MULTIMETER: Several instrumentsor ISOBALLAST CURVES (Lines):Precalculated instrumentcircuitscombined in a single lines appearing on recorder charts.Indicates enclosure and used in measuring two or more buoyancy (used on submarines). electrical quantitiec in a circuit. OCEANOGRAPI IY or OCEANOGRAPI ISOTHERMAL LAYER: A layer of water in Branch of sciencedealingwiththeOcean: whichthere is noappreciablechangeof pertain;ng to the ocean. temperature with derqh. PASSIVE SONAR: An appnatus that receives ISOVELOCITY LAYER: A layer of water in energy generated from another source. which there is no appreciable change of sound velocity with depth. PIEZOELECTRIC: The property of certain crystals which produce voltage when subjected kHz (Kilohertz):A prefix representing 103 or to a mechanical stress. 1000. PMS:Planned Maintenance Subsystem. LAYER DEPTH:The depth from the surface of the sea to the top of the first significant QUENCHING: The reduction in underwater negative thermocline. sound transmission or reception resulting from Q75 INTRODUCTION TO SONAR

absorption art,scattering of sound energy by air SONAR: Acronym for SOund Navigation And bubbles entrapped around the 3onar dome. RanOng. Apparatus or technique of obtaining i n formationreguardingobjectsorevents RANGE:The distance an object from an underwater. observer. SONIC:Within the audible range of the human RAREFACTION:In ,,Tve motion, when the ear. vibration is inward, a racefacionor region of reduced pressure is produced. SONOBUOY: Smallfloating buoy with an attached hydrophone and a radio transmitter RATE TESTS:Tests of own ship and target that relays underwater sounds pickedup by the rate mechanisms by having certain components hydrophone to ASW units. generate movement for a certain time frame. SOUND CHANNEL: Condition when two RDT: Rotating dliectional transmission. layers of water with near equal temperatures produce a sound channel. Sound betweenthe REFLECTION, SOUND: S o undrays two layersisrefracted!lythe layers, stays transmitted in the sea eventually reach either the between them, and travels for great distances. surface or the bottom. Since these boundaries areabruptandverydifferentinsound S / P : Soundpowered.Example: transmitting properties from the water, sound Sound-powered phones. Shipboard system using energy along a ray path striking tl s. boundaries voice toactivatecircuits.(Nobatteriesor will be returned (reflected) to the water. external power.)

REFRACTION, SOUND: Thebendingor SSXBT (Submarine Expendable BT):Tempera- curving of,,und ray that results when the ray ture versus depth plot to 2500 feet. passes from a re0on of one sound velocity to a region of a different velocity. The amount ofray STATIC TEST: A st using fixed inputs with bending depends on the amount of difference the problem stopped at a fixed point. Outputs between sound velocities. (or answers) are also fixed.

RELATIVE BEARING: The angle between SUBROC:Submarine-installed weapon system ships head andanobjectmeasured ina de sig dasde fenseagainsthigh-speed clockwise direction. nuclear-powered submarines.

RELATIVE MOTION: Theapparent SUBSONIC (Infrasonic): A frequency below movement of an object in relation to another the audio ranw.. object. TARGET ANGLE: The relative bearing ofthe REVERBERATION:The combined sound of surface ship from the target. many small echoes returned to the hydrophone by reflection from the surface, at the bottom, TARGET ASPECT:The relative position of and particles in the water. the submarine with respect to the soundbeam. R/T:Radio Telephone. THERMAL NOISE:A very !ow level nois,_. produced by molecular movement in thesea. SCANNING SONAR: Sonar that transmits sound pulses in all directions simultaneously. THERMISTER: A solid state, szifiti-conducting device whose resistance varies withtemperature. SCATTERING: R eflectionlossesfrom THERMOCLINE:A region of relatively rapid particles suspended in the water. decrease in temperature. S 1 176 Appendix I--GLOSSARY

3-M SYSTEM:Maintenance and Material Man- variable depth, are not usually included iu this agement system. category.

TRANSDUCER: A device used to convert VELOCITY:A vector quantuy that includes electrical energy to mechanical energy. both magnitude (speed) and direction bi relation to a given frame of reference. TRANSFER: After rudderisapplied,the distance moved at right angles to the original VERTICAL PLANE: Averticalplaneis course during the turn. perpendicular to the horizontal plane, zind is the reference from which beringsart_measured. TRUE BEARING: The angle from north to the Relative bearing, for exampie, is measured in the line of sight, measured clockwise through 3600. horizontalphine clockwise from the vertical planethrough own ship'scenterlinetothe TRUE MOTION:The movement of an object vertical plane through the line of sight. The across the earth, using true (geographic) north as system of planes makes possible the deisgn and the reference point. constructionofmechanicalandelectronic equipment to solve the fire control problem. TURN COUNTING: Counting revolutions ofa These lines and planes are imaginary extensions contact's propelkers to determine its speedor the of some characteristic of the shipor target, or of type of ship. the relation in space betv.een

UB PLOT: UnderwaterBatteryPlot.Fire WAVELENGTH:The d'tc.. between points control equipment installed here. correspon(li p!' two conseeut ive cycles. UBFCS (UBWCS):Underwater I3atteryFire Control System. Example: Mk 114 FCS. WIRE-GUI1Yr.:1) r0.10. . Tolpedo liaked to theship byawire tigunghwbr..h sHp czni ULTRASONIC: Having a frequency above the insmir guich.nce and Lonlnan iis to th2 audible sound. iornedo and the torrcdo cartcansirits,atus signals tc, the ship. VARIABLE DEPTH SONAR (VDS): The term is normally used to describe sonar whose BT 1a4.hvtl,crh1c1aph): A transducer is towed beneath its parent ship with uce -that ,iutomarir__Oly ploTs a graph showing the object of improving sonar deteionranges. temperatureasa ofdepth when Helicopterandsubmarinesonars,though lov.-2red into the sea.

2

177 INDEX

A Bathytherrnograph (SSBXT) submarine expendabk.,, 62 Access, 163 Bathythermogaph system surface ship Accountability, 165 expendable, 62-64 Active sonar, 85-87 Bathythermograph systems submarine. 59-62 Advancement examination, 11 Bearing drift, 80 Advancement, how to qualify for, 11-14 Bearings, 72-78 Aircraft, 32-34 converting true and relative bearings, antisubmarir :craft, 34 76-78 patrol pla gyro failure, 75 Aircraft, antif ,N ine, 34 relative bearings, 73 Aircraft c- ';V), 25 stern line indicator, 74 Alien, 16, true bearings, 73 Allied cornmt -cation publications, 10 Bearings and motion, 71-84 Ambient noise, 11-44 Bearings relative, 73 Antisubmarine i',:..craft, 34 Bearings, true, 73 Antisubmarine armanent, 29-32 ASROC, 30 torpedoes, 30-32 Antisubmarine units, 24-29 aircraf' L.wier (CV), 25 Call signs, 130 destroyer (DD), 25 Capacitors, i 53 frigate (FF), 26 Ca,-rier, aircraft (CV), 25 guided-missile cruiser (CG) (CGN), 29 Categories, classific:Ition, 165 guided-missile destroyer (DDG), 25 Censorship. person.d, 169 guided-missile frigate (FFG), 26-29 Characteristics of sound, 39 Appendix IGlossary, 173-177 Classification, 163 Armament, antisubmarine, 29-32 Classification categories, 165 Armament, submarine, 19-24 confidential, 165 ASROC, 30 secret, 165 ASW, history and development of, 15-34 top secret, 165 Attack submarines (SSN), 19 Classification guide, Classified informatiol., 163 Classifier, 163 Clearance, 163 Ballistic solution phase, 114 Clearances, security, 167 Basic fire control, 109-126 Code, 132-134 Bathythermogaph, 58-70 Code practice, 134-137 Bathythermograph logs, 70 18 3 prosigns, 135-137 178 INDEX

Communications, 127-140 Detection-to-destruction phases, 113-115 Communications, external, 129-132 ballistic solution phase, 114 Communications, internal, 1 27-1 29 destruction phase, 114 Communications, underwater, 137-140 detection phase, 113 Competent authoritycommanding officer, 163 target motion analysis pha, 114 Compromise, 163, 168 tracking phase, 113 Computing target angle, F!.1-84 Development and history of ASW, 15-34 Confidential, 165 Dipping sonar, 98 Control, personnel, 167 Disciplinary action for security violations, 169 Converting true and relativt. bearings, 76-78 Dissemination policy, 170-172 Cruiser, guided-missile, (CG) (CGN), 29 Document, 164 Custodian, 164 Doppler and reverberations, 53 Doppler and target aspect, 80 Doppler effect, 53-55 doppler and reverberations. 53 doppler reports, 54 Doppler/no doppler, 55 Daily heating, 65-70 Doppler reports, 54 Data, restricted, 164 Downgrade, 164 Declassifk tion, Deep water sound propagation, 51-53 Definitions, 162-165 access, 163 alien, 163 Echo strength, 56 classification, 163 Echoes from false targets, 56 cicissification guide, 163 Echoes, interpreting, 55-57 classified information, 163 Effects of temperature, 58 classified material, 163 temperature layers, 58 classifier, 163 EIBs and EIMBs, 8 clearance, 163 EIMBs and EIBs, 8 competent authority--commanding officer, Electric shock, 143 163 Enlisted rating structure, 2 compromise, 163 . sonar technician rating, 2 custodian, 164 Equipment, 118 declassification, 164 Equipment, test, 144-147 document, 164 Examination, advancemeni I! downgrade, 164 External communications, I formerly restricted data, 164 call signs, 130 marking, 164 prowords, 130-13'7 need to know, 164 radiotelephone, 11J restricted data, 164 radiotelephone proced.,,res, 12) security, 164 upgrade, 164 Depth sow der (fathometer) 100-104 Depth-Fo.ind speed measuring set AN/BQH-1A, 59-62 Fire control, basic, 109-126 Designation, terminal, 148-150 Fire control nomenclature, 116 Destroyer, (DD), 25 Fire control system, representativeunderwa ter, Destroyer, guided-missile (DDG), 25 109 Destruction phase, 114 Fire control system tests, 122-125 Detecti(7r. phase, 113 , 4 1 Fire control systems, underwater. 1' 9-122

179 INTRODUCTION TO SONAR

Fire control, underwater, 109 Interpreting dial readings, 125 Fleet ballistic missile submarines (SSBN), 19 Interpreting echoes, 55-57 Fleet Ballistic missile system, 21-23 doppler/no doppler. 55 Formerly restricted data, 164 echo strength, 56 Frequency counter, 147 echoes from falk.. targets, 56 Frigate (FF), 26 Isothermal layer, 66 Frigate, guided-missile (FFG), 26-29 Fundamental problem, 115-126 equipment, I 18 fire control nomenclature, 116 fire control system tests, 1 22-1 25 Keeping up with new developments, 3 interpreting dial readings, 125 reference planes, 115 schematic identification of system components, 119 Leadership responsibilities, 2 sonar position quantities, 116-118 Logs, bathythermograph, 70 underwater fire control systc ins, 119-122 ri

Maintena nce, 1 54-1 61 General safety precautions, 141-143 maii,:nance and material management Generators, signal, 146 system, 156-161 Glossary, Appendix I, 173-177 types of maintenance, 154-156 Gradient, negative, 65 Maintenance and material management system, Gradient, positive, 65 156-161 Grounding test equipment, 143 Maintenance; test equipment; test methods, Guided-missile cruiser (CG) (CGN), 29 141-161 Guided-missile destroyer (DDG). 2S Maintenance, types of, 154-156 Guided-missile frigate (FFG), 26-2° Management system maintenance and material, Gyro failure, 75 1 56-1 61 Manufacturer's technical manual, 8 Marking, 164 Material and maintenance management system, 156-161 History and development of ASW, MC systems, 128 How to qualify bor adv-,:ement, 11-14 Measurement of sound, 40 Methods, submarine communication, 140 Methods, test, 147-154 Mines, 21 Missile system, fleet ballistic, 21-23 Indicator stern line, 74 Missile system, SUBROC, 23 Indicators remote, 128 Modern active sonar theory, 9 1-94 Information, classified, 163 Modern passive sonar theory, 96 Information sonar, 71 Morse code, international, 132-134 Internal communications, 127-129 Motion, 78 MC systems, 128 advance and transfer, 78-80 remote indicators, 128 bearing drift, 80 sound-powered phones, 127 doppler and target aspect, 80 International morse code, 132-134 relative motion, 78 the code, 132-134 true motion, 78 1 (0 5 180 INDEX

Motion and bearings, 71-84 Planes, reference, 115 Motion, relative, 78 Policy dissemination, 170-172 Motion, true, 78 Positive gradient, 65 Multimeter, 145 Power tools, safety with, 143 Practice, code, 134-137 Principles of sonar, 85-108 Principles, security, 162 NATO/Allied tactical doctrine publications,10 Problem, fundamental, 115-126 NAVEDTRA publications, 8 Procedure, voice, 137-140 NAVSEA (formerly NAVSHIPS) publications,8 Procedures, radiotelephone, 129 Negative gradient, 65 Propagation of sound in the sea, 47-53 Noise, 40 deep water sound propagation, 51-53 Noise, ambient, 41-44 structural conditions, 47 Nomenclature, fire conrtol, 116 Proper handling, 167 Prosigns, 135-137 Prowords, 130-132 0 Publications, allied communication, 10 Operation, 64 Publications, NATO/Allied tactical doctrine, 10 Oscilloscope, 145 Publications, NAVEDTRA, 8 Publications, NAVSEA (formerly NAVSHIPS), 8 Publications promulgated by CNO, 8 Publications promulgated by COMNAVCOMM, Passive sonar, 94-96 9 Patrol plane, 34 Publications, U.S. Communication, 10 Pelsonal censorship, 169 Publication. U.S. Navy tactical dnctrine, 9 Personnel control, 167 Purpose or the securityprogram, 62 Phase, ballistic solution, 114 Phase, destruction, 114 Phase, detection, 113 Phase, target motion analysis, 114 Phase, tracking, 113 Quenching, 47 Phases, detection-to-destructior 11-1 15 Phones, sound-powered, 127 Physi Jal security, 166 proper handling, 167 security areas, 166 Radiotelephone, I 2.v stowage,166 Radiotelephone procedures, 129 Physics of sound, 35-57 Rating, sonar technician, 2 ambient noise, 41-44 Rating structure, enlisted, 2 characteristics of sind, 39 Reading XBT recorder traces. 64-70 measurement of sou.,,i z1C daily heating, 67-70 noise, 40 isothermal layer.-.)6 quenching, 47 nc,;!ative gradient, 65 reflections, 45 positive gradi,mt, 65 refraction, 46 XBT trace marking, 70 (equiremnts for sound, 35-37 Reference planes. 115 reverberations, 46 Reflections, 45 sound waves, 37-39 Refraction, 46 transmission losses, 44 Relative bearings, 73 underwater sound Relative motion, 78 INTRODUCTION TO SONAR

Remote indicators, 12S Sonar position quantities, 116-118 Report everything you hear, 57 Sonar, principles of, 85-108 Representative underwater fire control Sonar systems, 85-108 system, 109 active sonar, 85-87 Reproduction or restraint, 169 depih sounder (fathometer), 100-104 Requirements for locating submarines, 71 dipping sonar, 98 sonar information, 71 modern active sonar theory, 91-94 Requirements for sound, 35-37 modern passive sonar theory, 96 Resistors, 150-153 passive sr nar, 94-96 Responsibilities and rewards of advancement, sonobuoys, 99 2-5 tape recorder, 104-108 Responsibilities, leadership, 2 transducers, 87-91 Restraint on reproduction, 169 ,ariable depth sonar (VDS), 97 Restricted data, 164 Sonar technician, 1-14 Restricted data, formerly, 164 Sonar technician rating, 2 Reverberations, 46 Sonar theory, modern active, 91-94 Reverberations and doppler, 53 Sonar theory, modern passive, 96 Rewards and responsibilities of advancement, Sonar variable depth (VDS), 97 Sonobuoys, 99 keeping up with new developments, 3 Sound, characteristics of, 39 leadership responsibilities, 2 Sound in the sea, propagation of, 47-53 working with others, 3-5 Sound, measurement of, 40 Sound, physics of, 35-57 Sound propagation, deep water, 5 1-53 Sound pulse, underwater, 44 Sound, requirements for, 35-37 Safety, 141-144 Sound A,aves, 37-39 electric shock, 143 Sound-powered phones, 127 general safety precautions, 141-143 Stern line indicator. 74 gounding test equipment, 143 Stowage, 166 safety with power tools, 143 Structural conditions, 47 Safety precautions, general, 141-143 Studying for the test, 5-11 Safety with power tools, 143 Allied communication publications, 10 Schematic identification of system components, EIBs and EIMBs, 8 119 manufacturer's technical manual, 8 Secret, 165 NATO/Allied tactical doctrine publications, Security, 162-172 10 Security areas, 166 NAVEDTRA publications, 8 Security clearances, 167 NAVSEA (formerly NAVSHIPS) personnel control. 167 publications, 8 Security, physical, 166 publications promulgated by CNO, 8 Security principles, 162 publications promulgated by Security program, purpose of, 162 COMNAVCOMM, 9 Security violations, disciplinary action for, U.S. communications publication, 10 169 U.S. Navy tactical doctrine publications, 9 Shock, electric, 143 Sul:, -arine, 15-19 Signal generators, 146 attack subma.:.-Ics (SSN), 19 Sonar, active, 85-87 fleet ballistic missile submarines Sonar dipping, 98 (SSBN), 19 Sonar information, 71 general description, 17-19 Sonar, passive, 94-96 17his,ory .nd development, 15-17 182 INDEX

Submarine armament, 19-24 Test equipment (Continued) fleet ballistic missile system, 21-23 oscilloscope, 145 mines, 21 signal generators, 146 SUBROC missile system, 23 transistor tester, 147 torpedoes, 20 Test equipmeni grounding, 143 Submarine A/S weapons, 112 Test equipment; test methods; maintenance, Submarine bathythermograph systems, 59-62 141-161 depth-sound speed measuring set AN/BQH-1A, 59-62 Test methods, 1 47-1 54 submarine expendable bathythermogaph capacitors, 153 (SSXBT), 62 resistors, 150-153 terminal designations, 148-150 Submarine communication methods, 140 Test methods; test eq,npment; maintenance, Submarine expendable bathythermograph 141-161 (SSXBT), 62 Submarines, requirements for locating, 71 Test, studying for, 5-1: Submarines (SSBN), fleet ballistic missile, 19 Tester, transistor, 147 Submarines (SSN), attack, 19 Top secret, 165 SUBROC missile system, 23 Torpedoes, 20, 30-32 Surface A/S weapons, 111 .1-acking phase, 113 Transducers, 87-91 Surface ship ex7,--,i.able bathythermouaph Transistor tester, 147 system, 62-6,1 Transmission losses, 44 operation, o-T True and r2lative 1:.earinf!s. convening. 76-78 System, bathythermograph surface ship 1,-/:::fmgs. 73 expendable, 62-64 True :notion, 78 Type,' of maintenance, 15 -156 System components, schematic identifHationof, 119-122 System tests, fire control, 122-125 Systems, MC, 128 Systems, sonar, 85-108 Underwater communications, 137-140 Systems, underwater Fre control, 119-11' submarine communications methods, 140 voice procedure, 137-140 Underwater fire control, 109 T representative underwater rire control system, 109 Tape recorder, 104-108 Und.:'rwater fire control systems, 119-122 Target and doppler aspect, 80 Underwater sound pulse, 44 Target ande, computing, 81-84 Units, antisubmarine, 24-29 Target motion analysis phase, 114 UpE-; ade, 164 Technical manual, manufacturer's, 8 U.S. communication publication, 10 Technician, sonar, 1-14 U.S. Navy tactical doctrine publications,9 Thrnperature, effects of, 58 mp er atur e layers, 58 Terminal designations, 148-150 V Test equipment, 144-147 freouency counter, i 47 Variable depth sonar (VDS), muitimeter, 145 Voice procedure: 137-140

183 1S8 INTRODUCTION TO SONAR

Weapons, surface A/S, ill Working with others, 3-5 Waves, sound, 37-39 Weapons, 110-113 submarine A/S weapons, 112 surface A/S weapons, III XBT recorder traces, reading, 64-70 Weapons, sublinrinc A/S, 112 XBT trace marking, 70

IJ)9

184 OCCUPATIONAL STANDARDS

Covered in Assignment or Bibliography Sonar Technician Third Class (Surface) & (Subn..irine) STG STS

14 ELECTRONICS MAIN IENANCE

14617 Identify underwater fire control symbols 4 14676 Identify standard electroniccomponent color coding 5 system 5

14963 Perform op:rational tests and make externaladjustments NT 10131 on equipment NT 10132

1.8 Ti.ST EQUIPMENT

18133 Operate general purpose test equipment 5 5

22 SENSOR OPERATIONS

22232 Identify sounds pi-oc!uced by surface ships,1, pedoes. submarines, evasion devices,sonar transmissions, marne life, and natural phenomena 22233 Interpret passive/active sonar recordertraces NT 1 0131 NT 1013:: 22234 Identify LOFAR contacts NS 0967 NS 0967 340-".020 3404020 22235 Operate !;onar sensors for de'-ction andclassification of 4 4 sonar contacts

22238 Distinguish the characteristics, fun,:tions and effectsof NT 10131 NT 10132 cc:-.trolled jamming and evasive &viceson sonar operations 22240 Determine range predictions 1 0 2 185 Covered in Assignment or Bibliography

Sonar Technician Third Class (Surface) & (Submarine) STG STS 22 SENSOR OPERATIONS (Continued)

22241 Prepare and interpret sonar messages -

22141 Interpret acoustic conditions to determine best submarine conditions to avoid detection

11243 Classify and record contacts NT 10131 NT 10132

21144 Determine: 3 3 A. True and relative bearings B. Range actions C. Target angle, target aspect and Doppler D. True and relative motion and target course

22156 Construct and interpret the following sonar plots: NT 10132 A. Time bearing (Barnard) plm B. Relative motion (Lynch) plot C. Sonar navigational (Strip) plot D. Time/Range plot

21160 Locate primary/secondary and casualty power circuits NT 10131 NT 10132

21263 Recognize major equipment malfunctions during sensor NT 10131 NT 10132 operations

22802 Operate tape recorder 6 6

22804 Operate bathy thermograph 4 4

22806 Operate the underwater fire control system including NT 10131 dizd readbig and positioning operational controls to predetermined values

24 ELECTRICAL MAINTENANCE

24526 Inspect and clean commutators and slipring assemblies: 5 5 inspect and replace brushes

24571 Inspect, clean, and tighten or replace stylus NS 0967 NS 0967 WO 0130 000 0130 28 TECHNICAL DRAWINGS

28080 Identify electronic components on schematics :ind trace NT 10087 NT 10087 major signal flow Covered in AssignmentOr IinriIPhV Sonar Technician ThirdOass (Surface) & (Submarine) STt; STS 51 MAINTENANCE PLANNING AND QUALITYASSURANCE 51011 Complete maintenance dataforms for: OPNAV OPNAV A. Completed maintenanceactions (NIAE) INsT INST B. Deferred maintenanceaction-. C. Work requests 4790.4 4790.4

51026 Use maintenance reqnirementcards (MR0 ()kNAV OPNAV INST INST 4790.4 4790,4 86 COM \!!

8608 .Jperate Inderwater tHophone 5 5 860-- iiterior communicationsfacilities associated with 4 .,or operations 4

;ATION &ND TACTWALSUPP(H,T 8722 i Oprate fathometer 3 t.ROMECHANICAL MAINTENANCE L091 Inspect, clean and lubricate electromechanical equipment NS 096- NS 0967 000 0130 000 0130 94 MECHANICALMAINTENANCE 94764 Use and maintain handtools and portable power tools 5 5

11,2

187 INTRODUCTION TO SONAR NAVEDTRA 10130-C

Prepared by the Naval Education and Training Program Development Center, Pensacola, Florida

Your NRCC contains a set of assign- higher. If you are on active duty, the ments and self-scoring answer sheets average of your grades in all assign- (packaged separately) .The Rate Training. ments must be at least 3.2. If you are Manual, Introduction to Sonar, NOT on active duty, the average of your NAVEDTRA 10130-C , is your textbook for grades in all assignments of each the NRCC. If an errata sheet comes with creditable unit must be at least 3.2. the NRCC, make all indicated changes or The unit breakdown of the course, If corrections. Do not change or correct any, is shown later under Naval Reserve the textbook ..)1" assignments in any other Retirement Credit. way. WHEN YOUR COURSE IS ADMINISTERED HOW TO COMPLETE THIS COURSE SUCCESSFULLY BY LOCAL COMMAND Study the textbook pages given at As soon as you have finished an the beginning of each assignment before assignment, submit the completed self- trying to answer the items. Pay attention scoring answer sheet to the officer to tables and illustrations as they designated to administer it. He will contain a lot of information. Making yoUr check the accuracy of your score and own drawings can help you understand the discuss with you the items that you do subject matter. Also, read the learning not understand. You may wish to record objectives that precede the sets of items.your 3core on the assignment itself since The learning objectives and items are the self-scoring answer sheet is not based on the subject matter or study returned. material in the textbook. The objectivr..s tell you what you should be Able to do If you are completing this NRCC to by studying assigned textual material become eligible to take the fleetwide and answering the items. advancement examination, follow a schedule that will enable you to complete At this point you should be ready all assignments in time. Your schedule to answer the items in the assignment. should call for the completion of at Read each item carefully. Select the least one assignment per month. BEST ANSWER for each item, consulting your textbook when necessary. Be sure Although you complete the course to select the BEST ANSWER from the successfully, the Naval Education and subject matter in the textbook. You may Training Program Development Center will discuss difficult points in the course not issue you a letter of satisfactory with others. However, the answer you completion. Your command will make a nr,te select must be your own. Use only the in your service record, giving you credit self-scoring answer sheet designated for your work. for your assignment. Follow the scoring directions given on the answer sheet WHEN YOUR COURSE IS ADMININTERED itself and elsewhere in this course. BY THE NAVAL EDUCATION AND TRAINING PROGRAM DEVELOPMENT CENTER Your NRCC will be administered by you:: command or, in the case of small After finishing an assignment, go commands, by the Naval Education and on to the next. Retain each completed Training Program Development Center. self-scoring answer sheet until you No matter who administers your course finish all the assignments in a unit (or you can complete it successfully by in the course if it is not divided into earning grades that average 3.2 or units) .Using the envelopes provided,

1 5 3 mail your self-scored answer sheets to theNAVAL RESERVE RETIREMENT CREDIT Naval Education and Training Program Development Center where the scores will The course is evaluated at 10 Naval be verified and recorded. Make sure all Reserve retirement points, which will be blanks at the top of each answer sheet credited upon satisfactory completion of are filled in. Unless you furnish all the the entire course. These points are information required, it will be creditable to personnel eligible to receive impossible to give you credit for your them under current directives governing the work. You may.wish to record your scores retirement of Naval Reserve personnel. on the assignments since the self-scoringCredit cannot be given again for this answer sheets are not returned. course if the student has previously received credit tor completing another The Naval Education and Training Introduction to Sonar NRCC or ECC. Program Development Center will issue a letter of satisfactory completion to certify successful completion of the course (or a creditable unit of the course). To receive a course-completion letter, follow the directions liven oa the course-completion form in the back of this NRCC. You may keep the textbook and assignments for this course. Return them only_ in the event you disenroll from the course or otherwise fail to complete the COURSE OBJECTIVE course. Directions for returning the textbook and assignments are given on the While completing this course, the book-return form in the back of this student will demonstrate his understanding NRCC. of the course materials by correctly answering items on the following: procedures PREPARING FOR YOUR ADVANCEMENT for advancement to the petty officer level EXAMINATION and the duties and responsibilities of the STG and STS 3&2; major sound propagation Your examination for advancement is factors and terms used; types of ASW attacks, based on the Manual of Navy Enlisted Man- stations and communications; on board methods power and Personnel Classification and and components, and functions, of passive Occupational Standards (NAVPERS 18068-D). and active sonars; operational capabilities The sources of questions in this examina-and characteristics of auxiliary sonar tion Fre given in the Bibliography for Ad-equipment; duties and qualities of a sonar vancement Study (NAVEDTRA 10052). Since watchstander; basic introduction to your NRCC and textbook are among the integrated fire control systems; evaluation sources listed in this bibliography, be and classification of sonar targets; sure to study both in prepating to take identification of evasive maneuvers and your advancement examination. The stand- countermeasures devices; maintenance, ards for your rating may have changed tes*ing, and calibration methods and since your course and textbook were procedures; and personnel responsibility printed, so refer to the latest editions for security of classified 1,:aterial. of NAVPERS 18068-D and NAVEDTRA 10052.

While working on this nonresident career course, you may refer freely to the text. You may seek advice and instruc- tion from others on problems arising in the course, but the solutions submitted must be the result of four own worx and decisions. You are pro-ibited from re- ferring to or copying the solutions of others, or giving completed solutions to anyone else taking the same course.

ii Naval nonresident career courses may include a variety of items -- multiple-choice, true-false matching, etc. The items are not grouped by type; regardless of type, they are presented in the sar general sequence as the textbook material upon which they are based. This presentation is designed to preserve continuity of thought, permitting step-by-step development of ideas. Some courses use many types of items, others only a few. The student can readily identify the type of each item (one the action required of him) through inspection of the samples given below.

MULTIPLE-CHOICE ITEMS Each item contains several alternatives, one of which provides the best answer to the item. Select the best alternative and erase the appropriate box on the answer sheet.

SAMPLE s-1. The first person to be appointed SecretarTOTTefense The erasure of a correct answer is in- under the National Security Act of 1947 was dicated in this way on the answer sheet 1. George Marshall 2. James Forrestal 1.. 3 4 3. Chester Nimitz 4. William Halsey 5-1 C I

TRUE-FALSE ITEMS Determine if the statement is true or false. If any part of the statement is false the state- ment is to be considered false. Erase the appropriate box on the answer sheet as indicated below. The erasure of a correct answer is also SAMPLE s-2. Any naval officer is authorized to corresi51570-- indicated in this way on the answer officially with a bureau of the Navy Department sheet:

without his commanding officer's endorsement. 1 2 3 4 TIFI I MATCHING ITEMS s-2 . Each set of items consists of two columns, each listing wor is to select the item in column B which is the best match for the item in column A that is being considered. Specific instructions are given with each set of items. Select the numbers identifying the answers and erase the appropriate boxes on the answer sheet.

SAMPLE Tn items s-3 through s-6, match the name of the shipboard officer in column A by selecting from column B the name of the department in which the officer functions.

A. Officers B. Departments The erasure of a correct answer is in- dicated in this way on the answer sheet s-3.Damage Control Assistant 1. Operations Department

1 2 3 s-4. CIC Officer 2. Engineering Department T F FM C s-5. Assistant for Disbursing 3. Supply Department 11=1C s-5 s-6. Communications Officer s-6 C

How To Score Your Immediate Knowledge of Results (IKOR) Answer Sheets

1 4 Total the number of in- Sample only T correct erasures (those Number of boxes 1 1 that show page numbers) erased incorrectly 0-2 3-7 C 9 24. for each item and place >in the blank space at Your score 4.0 3.9 11CC 12 I the end of each item.

Now TOTAL the column(s) of incorrect erasures and findyour score in the Table at the bottom of EACHanswer sheet.

NOTICE: If, on erasing, a page number appears, review text (startingon that page) and erase again until "C", "CC", or "CCC" 4pears. For courses administered by the Center, the maximum number of points (or incorrect erasures) will be deducted fromeach item which does NOT have a "C", "CC", or "CCC" uncovered (i.e., 3 pts: for four choice items, 2 pts. for threechoice items, and 1pt. for T/F items). Assignment 1

The Sonar Technician; History and Develcpment: Physicsof Sound Textbook, NAVEDTRA 10130-C: Pages 1 thru 40

In this course yoU will demonstrate that learninghas taken place by correctly answering training itPms. The mere physical act of indicating a choiceon an answer sheet is not in itself important; it is the mental achievement, in whatever form itmay take, prior to the physical act that is important and toward which nonresident careercourse learning objectives are directed. The selection of the correct choice fora course training item indicates that you have fulfilled, at least in part, the stated objective(s).

The accomplishment of certain objectives, for example,a physical act such as drafting a memo, cannot readily be determined by means of objective typecourse items; however, you can demonstrate by means of answers to training items thatyou have acquired the requisite knowledge to perform the physical act. The accomplishment of certain other learning objectives, for example, the mental acts of comparing, recognizing, evaluating,choosing, selecting, etc., may be readily demonstrated in a course by indicating thecorrect answers to training items.

The comprehensive objective for this course has alreadybeen given. It states the purpose of the course in term3 of what you will beable to do as you complete the course.

The detailed objectives in each assignment state whatyou should accomplish as you progress through the course. They may appear-singly or in clusters of closely related objectives,as appropriate; they are followed by items which will enableyou to indicate your accomplishment.

A11 objectives in this course are learning objectivesand items are teaching items. They point out important things, they assist in learning, andthey should enable you to do a better job for the Navy.

This self-study course is only one part of thetotal Navy training program; by its very nature it can take you only part of the way toa training goal. Practical experience, schools, selected reading, and the desire to accomplishare also necessary to round out a fully meaningful training program.

Learning Objective: Acquaint 1-3 Which of the following would be the new ST with the basics of considered a general rating? the ST rating. 1. STG2 2. STS3 3. STSC 1-1. How does the U. S. prepare itself 4. STCM to meet a potantial submarine threat? 1-4 Which of the following equipments 1. Conducts antisubmarine walfare is not normally maintained by an (ASW) exercise. STS? 2. Revises ASW tactics. 1. Fire control 3. Evaluates new equipment. 2. Active sonar 4. Does all of the above. 3. Passive sonar 4. Oceanographic 1-2. Nuclear submarines are advantageous in ASW operations because theycan 1. screen the area for surface ships 2. select the best depth for opera- tions 3. conduct operations over wide ocean areas 4. accomplish either 2 or 3 above 1

196 1-11. In what publication will you find Learning Objective: Explain the an up-to-date list of the quali- rewards of being an ST, the fications for advancement? methods of advancement, and the sources of information for study. 1-12. Which of the following publica- tions come under cognizance of COMNAVCOMM? 1-5. What type of ship would an STG 1. ACPs most likely be sent aboard after 2. DNCs he attends "A" school? 3. JANAPs 1. Destroyer tender 4. All of the above 2. Destroyer 3. Minesweeper Use the following alternatives 4. Submarine for items 1-13 thru 1-16. 1. NWP 0 1-6. Which of the following are con- 2. NWIP 1-4 sidered advantages of advancement? 3. NWIP 11-20 1. Higher pay 4. NWP 16 2. Greater prestige 3. Getting ahead in chosen career 1-13. Which publication establishes 4. All the above the basic operational communica- tions doctrine? 1-7. Which of the following publica- tions should you use when study- 1-14. Which publication provides guid- ing the Military Requirements ance for the operation of a COMTAC for Advancement to P03? library? 1. NAVEDTRA 10052 2. NAVEDTRA 10061 1-15. Which publication lists the mis- 3. NAVEDTRA 10056 sions and characteristics of U.S. 4. WAVEDTRA 10130 Navy ships?

1-8. You can keep abreast of new devel- 1-16. Which publication contains exper- opments that affect you, your work, imental tactics and procedures? and the Navy by being able to 1. find up-to-date information Use the following alternatives and check that which pertains to for items 1-17 thru 1-20. your specialty 1. ATP 1 2. collect 1D-rsona1 copies of 2. FXP 1 appropriate technical manuals 3. ATP 28 (USN ADDENDUM) 3. complete all correspondence 4. AXP 1 courses that pertain to your rating 1-17. Which publication establishes 4. complete all correspondence tactics and procedures for con- courses that pertain to the ducting submarine exercises? deck group 1-18. Which publication contains the 1-9. Which of the following is the basic concepts and principals of basic purpose of all communication? ASW operations? 1. Knowledge of own language 2. Understanding 1-19. Which publication establishes 3. Effective leadership tact;.cs and procedures for eval- 4. All of the above uating Allied antisubmarine exercises? Use the followng alternatives for items 1-10 and 1-11. 1-20. Which publication contains basic 1. NAVEDTRA 1414/1 maneuvering instructions? 2. NAVEDTRA 10052 3. NAVEDTRA 10061 4. NAVPERS 8068

1-10. Which publication 7ontains a list of study material 1:or advancement examinations? 5 7 2 1-21. Which of the following actions, 1-27. if any, is taken when A submarine was first used as an an outdated offensive weapon during what war? question is found on an advance- ment examination? 1. Spanish-American War 2. American Revolutionary War 1. The old correct answer is 3. WW I counted. 4. WW II 2. All four answers are counted correct. 1-28. The submarine's greatest advan- 3. All four answers are counted tage is that wrong. 1. 4. None of the above are done. it is very difficult to sink 2. it has more potent weapons 3. its crew is smaller than a 1-22. What is the purpose of thepro- file sheet? surface ship's 1. To verify your advancement 4. it can operate beneath thesur- face of the ocean where detec- 2. To compare overall examination tion is difficult performance 3. To point out weak areas 1-29. Which of the following statements 4. To assign a numerical grade for each section correctly describes the origins of sonar? 1-23. How many months must an active 1. A device called ASDIC was first duty STGSN serve to be eligible developed by America and was for STG3? later improved by Britain and renamed sonar. 1. 4 2. 6 2. A device called a sound fathom- 3. 12 eter was first developed by 4. 18 Britain and was designed for A/S use by America and renamed 1-24. In what grade does an inactive sonar. duty Sonar Technician require 3. A device called ASDIC was first selection board approval for developed by Britain and was advancement? later improved by America and 1. E-4 renamed sonar. 2. E-5 4. A device called a sound fathom- 3. E-6 eter was first developed by 4. E-7 America and was redesigned for A/S use by Britain and renamed 1-25. After you pass the written exami- sonar. nation, what other factor will 1-30. limit advancement? The Skipjack differs from other 1. Rating quotas nuclear submarines primarily in its 2. Time in grade 1. hull design 3. Practical factors 4. Duty stations 2. ability to carry ballistic missiles 3. type of propulsion plant 4. cruising range

Learning Objective: Provide 1-31. the new ST with the background Which of the following groups of of ASW and submarine. submarine classes is arranged in order of increasing displacement? 1. X-1, Seahound, Shrimp 1-26. 2. Shrimp, X-1, Seahound It is necessary for a Sonar 3. X-1, Shrimp, Seahound Technician to be thoroughly 4. Seahound, X-1, Shrimp familiar with the capabilities of enemy submarines in order to 1-32. Which of the following is the 1. detect them easier main limitation to a modern 2. hold contact after detection submarine's ability to stay 3. aid in hunt and destroy submerged at sea? operations 1. Fuel shortage 4. do all of the above 2. Equipr.ent failures 3. Navigation errors 4. Human endurance and supply space 3

1 f) 8 1-33 Which of the following submarines was created to act as a nuclear Learning Objective: Aquaint the deterrent to a general war? new ST with the different types 1. Guppy II of missiles used in the Navy and 2. SSBN the types of launching platforms 3. SSN fast attack (conventional used. hull) 4. SSN fast attack (albacore hull) 1-41. Which missile will contain mul- 1-34. The primary mission of the attack tiple warheads? submarine is 1. Point defense 1. ASW 2. Polaris A3 2. barrier patrol 3. ASROC 3. avoiding detection 4. SUBROC 4. launching missiles 1-42. The SUBROC is which of the fol- lowing types of missiles? 1. Underwater-to-surface Learning Objective: Provide the 2. Surface-to-surface new ST with knowledge of the 3. Surface-to-air different types of torpedoes 4. Underwater-to-air-to-under- and mines. water

1-43. Which submarine-launched ASW Use the following alternatives weapon uses an inertial guidance for items 1-35 thru 1-38: system? 1. Wire-guided 1. Mk 45 torpedo 2. Straight-running 2. ASTOR 3. Active acoustic 3. SUBROC 4. Passive acoustic 4. ASROC

1-35. Which torpedo sends out pulses 1-44. At what point is guidance to the of sound and homes on echoes SUBROC missile terminated? that return from the target? 1.30 seconds after launch 2. When the guidance wire breaks 1-36. Which torpedo may be guided 3. At a predetermined height throughout its run by signals 4. At a preset depth from the launching ship? 1-45. Which of the following is/are 1-37. Which torpedo uses preset values the principal function/functions to Lntercept a target? of the destroyer? 1. Operating offensively against 1-38. Which torpedo depends upon tar- surface ships get noise for guidance? 2. Operating defensively against submarines 1-39. When secrecy is required for 3. Defending against air attack laying mines, what delivery 4. All of the above means is used? 1. Aircraft 1-46. Several postwar Foriest Sherman 2. Surface craft class destroyers have been con- 3. Submarines verted to DDGs by 4. Minelayers 1. replacing the #2 gun mount with a TARTAR missile launcher 1-40 All of the following mines may 2. replacing the #1 gun mount be programed to allow several with a TARTAR missile launcher ships to pass before exploding 3. replacing the after TARTER except missile launcher with a REGU- 1. acoustic LAS missile launcher 2. magnetic 4. replacing the ASROC launcher 3. pressure with a SPARROW missile 4. contact launcher

4

19 1-47. The USS BELKNAP (CG26) displaces how many tons? 1. 2200 Learning Objective: Define the 2. 4700 elements of and the requirements 3. 5400 for sound. 4. 6700

1-48. The ASROC missile can deliver 1-55. Whether a wave is transverse or which of the following payloads? longitudinal depends on the wave's 1. Depth charge 1. components of motion 2. Torpedo 2. frequency 3. Either 1 or 2 above 3. amplitude 4. Wire-guided torpedo 4. wavelength

Judge questions 1-49 thru 1-51 1-56. Sound waves vary in length True or False. according to their 1. amplitude The SUBROC missile with a torpedo 2. intensity payload uses parachute stabili- 3. frequency zation. 4. strength

1-50. The SUBROC missile with a depth 1-57. The upper limit of sound vibration charge payload uses either para- that can be detected by the aver- chute stabilization or fin stabil- age ear is about ization. 1. 10,000 vibrations per second 2. 15,000 vibrations per second 1-51. There are five principal ways to 3. 25,000 vibrations per second launch a torpedo. 4. 40,000 vibrations per second 1-52. Which of the following is an 1-58. Sound waves cannot travel through advantage of the Mk 46 torpedo a over the Mk 44 torpedo? 1. gas 1. Improved propulsive power 2. liquid 2. Greater cargo 3. solid 3. Greater speed 4. vacuum 4. All of the above 1-59. The sounds transmittedby the 1-53. How does MAD (magnetic anomaly modern sonar equipmentof the detection) equipment detect sub- 1970's fall within therange marines? designated 1. By measuring exhaust trail 1. sonic gases 2. subsonic 2. By measuring variations in the 3. ultrasonic Earth's magnetic lines of 4. supersonic force 3. By active sonar transmission 1-60. Sonar equipment is designed to 4. By measuring total magnetism convert returning echoes to a base of the submarine frequency of 800 Hz because an 800-Hz note 1-54. The Navy's newest fixed-wing ASW 1. can be reproduced easily aircraft is the 2. is louder than other audible 1. S2-F sounds 2. P-3 3. travels farther than other 3. SH-2F audible sounds 4. S-3A 4. is the most pleasing to the average human ear over long periods

5

200 1-61 How much of an increase or 1-67. If your sonar equipment has an decrease in sound intensity operating frequency of kHz, it or total power must take place has a wavelength in 39°F seawater before it can be detected by of the human ear? 1. 0.37 ft 1. 1/4 2.0.,45 ft 2. 1/3 3. 0.76 ft 3. 1/2 4. 0.96 ft 4. 3/4 1-68. The pitch of sound may be raised 1-62 Which of the following functions by is best performed by the human 1. increasing the amplitude of ear? the vibrations 1. Discrimination between sounds 2. decreasing the amplitude of of changing intensity the vibrations 2. Detecting changes at low 3. decreasing the rate of vibra- frequency tions 3. Detecting changes at high 4. inpreasing the rate of frequency vibrations 4. Discriminating between sounds of varying pitch Learning Objective: Explain the mathematical principles of Judge items 1-63 thru 1-65 True/ sound measurement. False.

1-63. The backward movement of a trans- 1-69. What is the third harmonic of ducer causes an area of low pres- a 1600-Hz tone? sure or a compression. 1. 3200 Hz 2. 4800 Hz 1-64. A wavelength is the distance from 3. 6400 Hz one point on a wave to the next 4. 8000 Hz point of similar compression. 1-70. Your sonar equipment has suffered 1-65. A sound wave may travel great a loss of 9 decibels in source distances at a high rate of level. How much of the original speed; however, the particles power does your equipment have within the medium move very little. left? 1. 12.5% 1-66. Why does sound travel faster 2. 15.0% through water than through air? 3. 25.0% 1. Because air is denser than 4. 50.0% water 2. Because water offers less 1-71. Which method is most practical resistance to waves than air to use for increasing the range 3. Because the particles in water of your sonar equipment? are closer together than the 1. Increasing the source level particles in air 2. Increasing the receiver sen- 4. Because the particles in water sitivity are farther apart than the 3. Reducing the local noise particles in air 4. Reducing the source level

2 0 1

6 Assignment 2

Physics of Sound (continued);Bathythermograph

Textbook, NAVEDTRA 10130-C: Pages 41 thru 70

2-5. How does a change in flow noise from laminar to turbulent affect Learning Objective: Define the noise intensity? various noise sources and thetypes 1. Increases sharply of noise they emit. 2. Increases gradually 3. Remains the same 4. Decreases 2-1. The foll,,wing three sources of noise _;r ::,mr--molecular motion, 2-6. wind on Flow noise and cavitation noise sea's surface, and are both produced by the move- sea lift--.re types of ment of an object through water. 1. flow noise One way they differ is that cavi- 2. ambient noise tation noise occurs 3. thermal noise 1. as soon as the object starts to 4. surface agitation noise move 2-2. 2. before flow noise occurs Which of the following noises is 3. when the pressure around the the result of molecular motion moving object fluctuates in the medium caused by tempera- 4. when air bubbles form around ture? the moving object 1. Thermal 2. Biological 2-7. 3. Flow As a propeller rotates in water, it will at different speeds of 4. Propulsion rotation produce (A) sheet cavi- tation, 2-3. (B) flow noise, and (C) Which o- the following is amore tip cwitation. In what sequence reliable measure of expected will tnese three types of noise ambient noise? be produced? 1. Windspeed 1. B, ,r C 2. Sea state 2. B, C, A 3. Surface temperature 3. C, A, B 4. Time of day 4, C, B, A 2-4. Which of the following noises 2-8. Your submarine commences cavitating that may be produced in a surface at a depth of 100 feet when the ship decreases the ability of the speed exceeds 6 knots. What hap- surface ship to detect underwater pens to the amplitude and fre- targets but, because it is not quency of the noise when the depth radiated appreciably, has little is increased to 200 feet and the effect on the ability of the speed remains the same? target to detect the surface 1. Amplitude increases, frequency ship? decreases 1. Flow noise 2. Amplitude increases, frequency 2. Cavitation noise increases 3. Main propulsion noise 3. Amplitude decreases, frequency 4. The rat-a-tat-tat of a chipping increases hammer 4. Amplitude decreases, frequency decreases

7 202 2-9. How does dynamic imbalance in 2-15 Which of the following trans- machinery become a sonar noise mission losses is independent problem? of frequency? 1. Leakage currents are creatud. 1. Attenuation 2. Static noises are fed into 2. Absorption the receiver. 3. Scattering 3. Vibration is changed to 4. Divergence acoustic energy. 4. The imbalance causes flow 2-16. The attenuation (decrease noise. in strength) of a sound beam is caused by the combined effects 2-10. What type of noise is made when of the anchor windlass is used? 1.absorptionandscattering 1. Surface agitation 2.absorptionandreflection 2. Thermal noise 3.reflectionandrefraction 3. Ambient noise 4.refractionandscattering 4. Self-noise 2-17. Reflection of sound energy occurs 2-11. Which of the follwing is the anytime the sound medium changes most probable cause of a 60-Hz in noise generated within the 1. thickness sonar equipment itself? 2. shape 1. A badly balanced shaft 3. density 2. Improperly shielded cable 4. temperature 3. Portable power tools 4. The fire and flushing pumps 2-18. What happens to sound energy that is transmitted from an 2-12. Which types of marine life underwater source when the sound could be mistaken for hydro- reaches the surface of the water? plane noise? 1. Most of it continues on into 1. Whale the air. 2. Porpoise 2. All of it continues on into 3. Seal the air. 4. Shrimp 3. Most of it is reflected down- ward into the water. 2-13. When you hear a noise made by 4. All of it is reflected down- marine life that sounds similar ward into the water. to burning brush, the depth of the mirine life is 2-19. In general, what kind of shallow 1. less than 30 fathoms bottom causes the least trans- 2. 100 fathoms or more mission loss? 3.300 fathoms 1. Smooth sand 4. 1000 fathoms 2. Rough gravel 3. Soft mud 2-14. Which of the following marine 4. Rough rocks life produce a sound similar to that of someone hammering? 2-20. When you transmit sound energy 1. Porpoises into the water, the many echoes 2. Snapping shrimp you receive from sources such 3. Sperm whales as the water mass, the surface, 4. Blackfish and the bottom of the sea, are called 1. reverberations 2. refractions Learning Objective: Define and 3. absorptions discuss the controlling factors 4. diversions of sound, their effects on the transmission of sound, and methods of recognizing the factors.

203

8 2-21. What causes volume reverberations: 2-27. How is the speed of a sound wave 1. Sound energy reradiated by traveling through water affected small particles by water temperature and pressure? 2. Surface and bottom reflections 1.Its speed increases when tem- 3. Marine life perature increases and also 4. All of the above when pressure increases. 2. Its speed decreases when tem- 2-22. Which of the following conditions perature increases and also will cause the highest reverbera- when pressure increases. tion levels? 3. Its speed increases when tem- 1. Flat surface and deep water perature increases and 2. Flat surface and smooth bottom decreases when pressure 3. Rough surface and rocky bottom increases. 4. Rough surface and smooth bottom 4. Its speed decreases when tem- perature increases and increasel 2-23. Two things that happen to the when pressure increases. sound beam when sound is trans- mitted into water are: (A) its 2-28. Which factor controlling the speed cross sectional area becomes of sound varies in direct pro- larger as the sound moves out portion to the water depth? from the source, and (B)its 1. Salinity direction is affected by water 2. Pressure pressure, salinity, and changes 3. Temperature in temperature. What are each 4. Density of these two effects called? 1. (A) scattering,(B) refraction 2-29. Which figure in the textbook shows 2. (A) divergence,(B) refraction the behavior of a sonar beam 3. (A) scattering,(B) reflection when it is influenced by water 4. (A) divergence,(B) reflection pressure only? 1. 3-15 2. 3-26 2-24. When a beam of sound passes from 3. 3-17 one medium of high temperature 4. 3-18 into a medium of low temperature, the sound beam is 2-30. Which figure in the textbookcor- 1. reflected rectly shows the behavior of 2. refracted a sonar beam in water that hasa 3. absorbed continuous negative thermal 4. scattered gradient? 1. 3-15 2-25. Which of the following sounds 2. 3-16 indicates that a sonar beam is 3. 3-17 being quenched? 4. 3-18 1. Hollow booming 2. Sharp pinging 2-31. A submarine using the layer effect 3. Shrill screech for protection will find the 4- Dull thudding most protection under conditions similar to those represented in 2-26. What is the most important factor the text book by figure affecting the speed of sound in 1. 3-15 water? 2. 3-16 1. Temperature 3. 3-17 2. Pressure 4. 3-18 3. Salinity 4. Chemical composition 2-32. Which, if any, of the following thermal gradients will produce layer depth at the depth of max- imum temperature? 1. Positive 2. Negative 3. Isovelocity 4. None of the above 204 9 2-33. Echo ranging in shallow water 2-38 Earlier in this assignment, the is difficult due to the sound relationship between a sound's being frequency, its velocity, and its 1. scattered wavelength was discussed. One 2. absorbed version of their relationship 3. reflected (F = V) applies very closely 4. refracted A to the discussion on the effects 2-34. What is the approximate depth of motion on sound. Compressing of a submarine if it passes under the sound wave is the same as a sonar beam so that contact is shortening the sound's wavelength. lost at 100 yards? What effect has an object's motion 1. 100 ft on the wavelength, and thu on 2. 200 ft the frequency of a sound that is 3. 300 ft coming from the'object, if the 4. 400 ft object is moving away from you? 1. The wavelength increases and 2-35. In a layer of water that provides the frequency goes up. a sound channel, what is the 2. The wavelength increases and relationship between the water the frequency goes down. temperatures at (A) the upper 3. The wavelength decreases and limit of the layer,(B) the the frequency goes up. lower limit of the layer, and 4. The wavelength decreases and (C) the axis of the layer? the frequency goes down. 1. A and B are the same, C is 2-39. Assume that you pick up a target cooler than A and P. on your sonar equipment. What 2. A and B are the same, C is may you decide about the target warmer than A and B if the pitch of the echo is lower 3. A and C are the same, B is than the pitch of the reverbera- cooler than A and C tions? 4. A and C are the same, B is 1. The target is approaching your warmer than A and C ship. 2. The target is moving away from 2-36. What condition must exist in your ship. order to have a convergence 3. The target is maintaining the zone effect? same position relative to your 1. A negative gradient at the ship. surface 4. The target is moving at con- 2. A sound channel axis between stant speed. 350 fathoms and 500 fathoms 3. A sound source in the sound 2-40. A report of "Doppler moderate, channel axis up," indicates that a target 4. A water depth of approximately is approaching your ship with a 2000 fathoms speed component of about 1.2 knots 2-37. The principle by which an object's 2.3 to 6 knots motion changes the pitch of a 3. 7 to 9 knots sound that comes from the 4. 10 knots object is called the 1. bounce principle 2-41. Which of the following may give 2. frequency shift principle a sharp echo with doppler? 3. convergence principle 1. Kelp bed 4. doppler 2. Fresh submarine ,.ake 3. Whale 4. Riptide

2-42. A poor quality echo is reflected from a stern aspect target because 1. the target area is small 2. the echo comes from multiple sources 3. wake interference reduces the signal 4. of all of the above factors 10

205 2-43. What action should you take when you hear unusual sounds while on watch? Learning Objective: Explain 1. Identify the sound, then the bathythermographs currently report it. used in the Navy, including 2. Report every unusual sound their operational characteristics. immediately. 3. Report it only if it is a submarine. 2-48. What is the sound velocity range 4. After a reasonable period for of the AN/BQH-1A? identification, make your 1.4000- 4800fps report. 2.4200- 5100fps 3.4600- 5100fps 4.4800- 5100fps Learning Objective: Explain the 2-49. A series of lines on the recorder effect of varying oceanographic chart of the AN/BQH-1A depth- conditions on the transmission sound speed measuring set aid of sound. a moving submarine in maintain- ing its trim. What are these lines called? 2-44 What single factor has the most 1. Isothermal pronounced effect on the speed of 2. Isometric sound wave travel through water? 3. Isoballast 1. Depth of water 4. Isodynamic 2. Salinity of water 3. Water temperature 2-50. Sensitivity of the velocity- 4. water pressure measuring portion of the AN/BQH-1A is sufficient to 2-45. How will an increase in the water indicate change-. in sound velocity temperature from 73°F to 74°F of affect the speed of sound passing 1. 0.1 fps through the water? 2.1 fps 1. The speed of sound will increase 3.3 fps approximately 6 feet per second. 4.5 fps 2. The speed of sound will increase approximately 2 feet per second. 2-51. Two sound heads, one mounted on 3. The speed of sound will the keel and the other on the decrease approximately 4 feet sail of a submarine, are used per second. to get accurate information 4. The speed of sound will concerning changing thermal decrease approximately 12 feet gradients affecting buoyancy per second. during diving operations. Which sound head is used when 2-46. What would be the relationship the submarine is (A) ascending of temperature verses depth in and (B) diving? a thermocline? 1. Both A and B, upper 1. The temperature remains constant 2. Both A and B, lower with depth. 3. A lower, g, upper 2. The temperature decreases with 4. A uPPer, B lower depth. 3. The temperature varies errati- 2-52. The AN/BQH-1A sonar set measures cally within the thermocline the velocity of sound in water as depth increases. by 4. The temperature remains constant 1. correlating the several known above and below the thermocline. factors 2. timing a transmitted pulse 2-47. What are the two effects a ther- between a transmitter and mocline has on sound energy that a receiver cause a sound beam's direction to 3. timing a transmitted pulse be distorted? from another submarine 1. Reflection and reverberations 4. determining echo intensity 2. Convergence and refraction from a transmission 3. Convergence and reverberations 4. Reflection and refraction 11

206 The depth scale of the AN/BQH-1A 2-59. What actuates the release mecha- depth-sound speed measuring set is nism on the SSXBT, causing the calibrated for a maximum depth of probe to descend? 1. 700 ft 1. Atmospheric pressure 2. 800 ft 2. Water pressure 3. 1500 ft 3. Commands from the launching 4. 4800 ft ship 4. A preset timer 2-54. One precaution you take when you operate the BQH-1A depth-speed 2-60. What component of the surface ship measuring set is to avoid expendable BT senses the changing 1. using the recorder unit temperatures? 2. energizing the lower sound 1. Thermometer head before the submarine is 2. Sound head completely submerged 3. Thermistor 3. energizing the upper sound head 4. Bourdon tube before the submarine is com- pletely submerged 2-61. The surface ship expendable BT 4. selecting an overlapping depth recorder begins marking tempera- scale ture when the 1. cannister is loaded into 2-55 When you shift from one 'ound head the launcher of the BQH-1A depth-sound speed 2. probe strikes the water measuring set to another head, 3. wire unreels from the probe what information do you receive 4. wire unreels from the cannister in addition to the velocity of sound? 2-62. What feature of the surface ship 1. Depth under the keel expendable BT allows a vertical 2. Distance to the surface descent of the probe? 3. Amount of radiated heat at the 1. Simultaneous unreelinc of the sound head in use wire from the cannistar probe 4. Difference in depth between 2. Spin stabilization of the the two sound heads probe 3. The weight of the probe 2-56. One emergency feature of the 4. The speed of the probe AN/BQH-1A is that the 1. depth may be read if the sound 2-63. What is the maximum operating neads fail depth of the surface ship expend- 2. sound velocity is always shown able BT? 3. depth reading is always shown 1. 1000 ft 4. depth and velocity circuitry 2. 1500 ft are combined 3. 2000 ft 4. 2500 ft 2-57 What is the maximum operating depth of the SSXBT? 1. 1000 ft 2. 1500 ft Learning Objective: Discuss 3. 2000 ft how information derived from 4. 2500 ft the BT may be used in ASW work.

2-58. Approximately how much time is required to complete a temperature 2-64 Which of the following tempera- profile after launching the SSXBT ture gradients will usually result down to its maximum operating in short target ranges? depth? 1. Negative 1. 1 min 2. Positive 2. 2 min 3. Isothermal 3. 3 min 4. Mixed 4.4 min

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12 2-65. Which of the following thermal 2-67. What will usually happen to the gradients is usually observed temperature of the water near in coastal waters? the surface after the sun sets? 1. Negative 1. Positive gradients will become 2. Positive isothermal. 3. Isothermal 2. Negative gradients will become 4. Mixed isothermal. 3. Negative gradients will become 2-66. What causes the phenomenon known positive. as afternoon effect? 4. Positive gradients will become 1. Tides negative. 2. The sun 3. Tradewinds 4. Waves

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208 Assignment 3

Bearings and Motion; Principles of Sonar

Textbook, NAVEDTRA 10130-C: Pages 71 thru 102

Learning Objective: Provide 3-5. A comparison of the uses of true the new ST with the basic and relative bearings in sonar mechanics of bearings and operating procedure reveals that ranges. 1. relative bearings are used as long as the ship's gyrocompass is operating properly 3-1. Which of the following is used as 2. relative bearings are used only a reference for computing true when the ship's gyrocompass bearings? fails 1. North-south axis 3. true bearings are used only 2. True north when the ship's gyrocompass 3. Geographic north fails 4. Magnetic north 4. true bearings are used at all times, regardless of the con- 3-2. What information do you need to dition of the ship's gyro locate accurately an underwater compass object in relation to your ship? 1. The direction of true north 2. A geographical reference point 3. The object's direction and distance 4. The depth of the water 3-3. Which of the following results may be obtained from a speedy determi- nation of correct bearing and range? ['OUR TARGET 1. A correct solution from the SHIF computer A 2. The exact target location 3. A successful attack 4. All of the above

3-4. How should you report a range of 2350 yards? ATARGET 1. Range two thousand three hundred and fifty V B 2. Range twenty three fifty 3. Range two three five oh 4. Range two three five zero Figure 3A.--Bearings.

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209 3-6. What is the true bearing of target 3-11. How will the positions of the dials A in figure 3A? in figure 5-5 change to indicate 1. 000° that your ship is on course 315° 2. 090° and that your sonar is trained on 3. 180° your starboard beam? 4. 270° 1. B will move clockwise 90° and A will move clockwise 045°. 3-7. What is the true bearing of target 2. Both A and B will move counter- B in figure 3A? clockwise 90°. 1. 000° 3. A will move counterclockwise 2. 090° 90° and B will remain in its 3. 180° present position. 4. 270° 4. B will move clockwise 90° and A will remain in its present 3-8. The relative bearing of target A position. in figure 3A is 1. 000° 2. 090° 3. 180° Learning Objective: Acquaint 4. 270° the new ST with the manipula- tion of bearings. 3-9. The relative bearing of target B in figure 3A is 1. 000° 3-12. If your ship is oncourse 090° 2. 090° true when you makesonar contact 3. 180° at 180° true, whatis the true 4. 270° bearing reading onyour stern line indicator? 1. 000° 2. 090° Learning Objective: Famil- 3. 180° iarize the new ST with types 4. 270° of bearing and range indica- tors. 3-13. Your ship is on a heading of 180° true and alters course right to 270° true. What change occurs to Information for items 3-10 and the stern line indicator? "F 3-11: Bearing indicators like 1. Rotates clockwise and stops on th,1 one in figure 5-5 in your text- 270° book are used to provide remote 2. Rotates counterclockwise and stations with true and relative sonar stops on 090° bearings. In these two items, the 3. Rotates clockwise and stops two dials on the indicator that move on 090° are referred to as dial A and dial B, 4. No change dial A being the one that has the diamond indicator, and B being the 3-14. If your ship's stern is 090° true inner dial--the one labeled Gyro- when she suffers a gyrocompass Compass Repeater. casualty, what is the stern line indicator reading after the 3-10. How will the positions of the casualty? dials in figure 5-5 change to 1. 000° relative indicate that your ship is on 2. 090° true course 045° and that your 3. 180° relative sonar is trained on the port 4. 270° true beam? 1. Both A and B will move clock- 3-15. If you are headed for a sonar wise 90°. contact at 135° true when a gyro- 2. Both A and B will move counter- compass failure occurs, what must clockwise 90°. you do with the console cursor to 3. A will move counterclockwise remain on target? 135° and B will remain in its 1. Turn it left 45°. present position. 2. Turn it left 135°. 4. B will move clockwise 90° and A 3. Turn it right 45°. will remain in its present 4. Turn it right 135°. position. 15

210 3-16. What is the true bearing of a 3-21. Your ship is on course 170° and target if your ship is headed you have the following bearing 2700 true and the target bearing and range information on a sub- is 270° relative? marine: 1. 000° 2. 090° Time Bearing Range 3. 180° 0010 220° 8000 4. 270° 0015 215° 6750 0020 209° 5700 3-17. Assume that a target is moving 0025 200° 4800 due east and that your destroyer is approaching it from the south. What will your ship do in relation At a range of 700 yards, the target to the target? is due north of your ship and the 1. Pass ahead conning officer orders a course of 2. Pass astern 045° to take a lead on the target. 3. Pass over After the change in course, the 4. Pass parallel cursor will be moved to show a relative bearing of the target of about 1. 000° Learning Objective: Acquaint 2. 045° the new ST with advance and 3. 180° transfer. 4. 310°

3-18. Your ship is on course 253° true 3-22. What is the distance along the old and the target bears 1090 relative. course that a ship covers between What is the true target bearing? the time that right rudder is 1. 002° applied and the time that the ship 2. 107° is steadied in its new course? 3. 144° 1. Drag 4. 182° 2. Cover 3. Transfer 3-19. Your ship is on course 035° true 4. Advance and the target bears 334° true. What is the target's relative 3-23. The distance your ship moves at bearing? right angles to the original 1. 009° course after rudder is applied 2. 119° is called 3. 154° 1. transfer 4. 299° 2. advance 3. drift 3-20. The relative motion of a target 4. set is the motion the target appears to have if you consider your ship 3-24. The bearing drift of a target as being indicates the direction of target 1. stopped (dead in the water) movement if your ship is on a 2. on course 0000 steady course at a constant speed 3. on course 1800 and the relative bearing to the 4. on course 090° or 270° target is approximately 1. 000° 2. 045° 3. 090° 4. 315°

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16 Learning Objective: Point 3-28. Your ship is headed directly out to the new ST the toward a target that has right relationship between bearing drift and up doppler. bearings and doppler. What is target aspect? 1. Port bow 2. Starboard bow 3. Direct bow 4. Port beam

3-29. If you use the quadrant method of determining target aspect as showl, in figure 5-13 of your Lextbook, a dotted line representing a port bow aspect will be located in quadrant 1. A 2.B 3. C 4. D 3-30. Your ship is on course 195° true, the submarine bears 187° true, and the bearing is steady with LE. dop- pler. What maneuver has the sub- marine performed if the doppler changes to down and the bearing drifts left? 1.Turnedright Figure 3B.--Aspect and Doppler. 2.Turnedleft 3.Turnedrightand stopped 4.Turnedleftand backed down In figure 3B the submarine is in the center on course 000°, speed 3-31. To determine target angle, you four knots. must effectively put yourself on the target. You perform this 3-25. What is the doppler and target operation in the target angle aspect when your ship is at formula by applying 180° to position "A"? 1. the target's true bearing 1. Up doppler, port bow aspect 2. the target's relative bearing 2. No doppler, port bow aspect 3. own ship's course 3. Down doppler, starboard bow 4. the target aspect aspect 4. No doppler, port beam aspect 3-32. You are on a surface ship headed 000° and a submarine on your star- 3-26. What is the doppler and target board beam is also headed 000°. aspect when your ship is stopped How will you report target angle, at position "B"? and how will the submarine sonar 1. Up doppler, starboard beam operator report angle on the bow? aspect 1. 090°, port 90 2. Down doppler, starboard beam 2. 090°, starboard 90 aspect 3. 270°, port 90 3. No doppler, aspect undetermined 4. 270°, starboard 90 4. No doppler, starboard quarter aspect 3-33. Your contact is on course 275° true, bearing 176° true. What 3-27. What is the sequence of doppler is the target angle? when your ship has circled the 1. 081° target clockwise from position "A" 2. 099° to "B" and has arrived at position 3. 261° "C"? 4. 289° 1. No, up, down 2. Up, no, up 3. No, no, down 4. Up, no, down

17 212 3-34. Your target is on course 334° and 3-39. What advantage does modern active the target bearing is 135°. What sonar have over searchlight sonar? is the target angle? 1. The ability to maintain contact 1. 161° on a maneuvering target 2. 315° 2. The ability to search quickly 3. 341° all around the ship 4. 351° 3. The ability to see a 360° video presentation 3-35. Your submarine has a contact 4. All of the above advantages bearing 260° true on course 300° true. What is the angle on the bow? 000° 1. 180°, starboard 2. 160°, port 3. 140°, port 4. 140°, starboard

Learning Objective: Explain the basic principles of sonar, both active and passive.

3-36. What target information can be expected from passive sonar systems? 1. Estimated bearing and accurate range 2. Accurate bearing and estimated range 3. Accurate bearing and range 4. Estimated bearing and range 180° 3-37. What device is used to convert sound energy into electrical Figure 3C.--Sonar CRT display. energy? 1. Transmitter Refer to figure 3C and use the 2. Transducer following alternatives for items 3. Receiver 3-40 thru 3-42. 4. Loudspeaker 1. Target motion 2. Target distance 3-38. The main function of modern sonar 3. Target bearing receivers is to provide signals 4. Target size for the 1. loudspeaker and for the video 3-40. What target information is deter- indicators mined by dimension A? 2. microphoneand for theloud- speaker 3-41. What target information is repre- 3. transducerand for thevideo sented by dimension B? indicators 4. transducerand for themicro- 3-42. What target characteristic do you phone estimate from dimension C?

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18 3-50. Electrostrictive transducer ele- Learning Objective: Describe ments are polarized by using transducers and hydrophones 1. permanent magnets and their functions. 2. laminated elements 3. wire coils 4. high voltage 3-43. The magnetostrictive process of signal conversion is caused by 1. changes in the dimension of metals placed in a magnetic Learning Objective: Discuss field the modern active sonar 2. changes in the dimension of theory, including transmis- crystals placed in a magnetic sion, reception, and preeen- field tation. 3. polarization of crystals 4. polarization of ceramics Use the following alternatives for 3-44. What is used to prevent frequency items 3-51 thru 3-53: doubling in a magnetostrictive 1. Control-indicator transducer? 2. Receiver-scanner 1. Mica insulation 3. Transmitter 2. Wire coils 4. Audiofrequency amplifier 3. Castor oil 4. Metal laminations 3-51. What unit contains the circuitry that initiates and determines the 3-45. Magnetostrictive transducer length of the transmitted pulse? elements used in scanning sonar are composed of 3-52. In what unit is the transmitted 1. nickel tubes pulse modulated to the operating 2. nickel laminations frequency? 3. ammonium dihydrogen phosphate 4. barium titanate 3-53. In which unit is the incoming echo signal strength increased before 3-46. The maintenance of the close con- it reaches the scanning switches? tact feature of the sonar unit causes the sound beam to Reverberations are used as the 1. bend upward pitch reference for echo doppler 2. bend downward discrimination. When your ship is mov- 3. increase in power ing, the change in wavelength caused by 4. expand horizontally the ship's motion causes the reverbera- tion pitch to be higher from the bow 3-47. What type of material is used in than from the beam or stern. The own a piezoelectric transducer? ship's doppler nullifier (ODN) circuitry 1. Magnets uses own ship's speed and sonar bearing 2. Nickel laminations inputs to correct this difference. When 3. Wire coils in use, the ODN circuitry causes the 4. Crystals reverberations received by a ship in motion to be of the same pitch as those 3-48. Which of the following crystals is received by a rThip that is drifting. relatively insensitive to tempera- ture changes? 3-54. When your sonar equipment has ODN 1. ADP circuits, how will the frequency 2. Rochelle salt of an echo from a stopped submarine 3. Tourmaline . .y if you gain contact on your 4. Lithium sulphate bow.and pass it astern? 1. Change from high to low 3-49. Electrostrictive transducer 2. Change from low to high elements are composed of 3. Increase steadily 1. nickel tubes 4. Remain the same 2. nickel laminations 3. ADP crystals 4. ceramics

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214 3-55. When a target echo shows at extreme 3-57.The sonar system shown in figure range on the cathode ray tube of 3D is capable of accurately deter- your sonar, what is the relative mining the sound source's value of the sawtooth voltage? 1. aspect 1. Maximum 2. range 2. Three-fourths 3. speed 3. One-half 4. bearing 4. Minimum 3-58. Which of the following items of 3-56. When, during the sweep cycle, is information will be given by the the cursor produced on the scope? bearing deviation indicator (BDI) 1. During the first half of the sonar system in figure 3D? 2. During the second half 1. Own ship's course must be 3. Between sweeps changed to starboard for maxi- 4. Continuously mum signal reception. 2. Hydrophone must be trained right for minimum phase differ- ence. 3. Hydrophone must be trained OWN SHIP'S right for maximum phase differ- COURSE ence. 4. Hydrophone must be trained \ left for minumum phase differ- \ ence. \ SOUND \ SOURCE 3-59. In figure 3D, the automatic target follower (ATF) serves to relay 1. training signals to the RLI 2. training signals to the train- ing mechanism 3. audible frequency target signals TRAINING to the audio amplifier MECHANISM 4. audible frequency target signals to the filter 3-60. What type of sonar is illustrated in figure 6-10 of the textbook? 1. Conformal passive array AUDIO AUTOMATIC 2. Circular passive array AMPUFIER TARGET FOLLOWER 3. Cylindrical hydrophone array 4. Single-line hydrophone

3-61. The compensator switch in an array type of passive sonar system pro- BAND PASS vides a function most similar to Fl LTER that provided by a single-line hydrophone system's 1. RL1 meter 2. audio amplifier 3. band pass filter 4. training mechanism BEARING DEVIATION INDICATOR 3-62. What reference point is used in B D passive array sonar to determine target bearing? 1. Center of the rotor plate 2. Center of the stator plate 3. Center of the compensator Figure 3D.--Single-line hydrophone switch system. 4. Center transducer element 215

20 3-63. The purpose of the lag linesin 3-67. On which of the five range scales the array sonar described inyour on the AN/UQN-1 does the scope textbook is to provide a visual presentation? 1. delay the signal from the 1. The 100 ft scale only hydrophones farthest from the 2. The 100 ft and 100 fathom sound source scales only 2. speed up the signal from the 3. The 100 fathom and 600 fathom hydrophones farthest from the scales only sound source 4. On all five scales 3. delay the signal from the hydro- phones nearest to the sound 3-68. What depth is indicated by the source last trace mark on the chart in 4. speed up the signal from the figure 6-17 in your textbook? hydrophones nearest to the 1. 400 feet sound source 2. 430 feet 3. 4000 feet 3-64. The audio amplifier input signal 4. 4300 feet is strongest when the 1. output of the lag lines is in 3-69. You are facing the chart on an phase AN/UQN-1 depth sounder. In what 2. output of the lag lines is not directions do the stylus and the in phase paper travel? 3. stator plate is centered 4. preamplifier output is not in Stylus Paper phase 1. Up right 2. Up left 3-65. Which of the following advantages 3. Down right do you have with variable depth 4. Down left sonar that you do not have with hull-mounted transducers': 3-70. Which of the following can be 1. Generally longer ranges controlled by reducing the gain 2. More accurate classification on the AN/UQN-1 depth sounder? 3. Faster search speeds 1. Solid line in shallow water 4. The ability to get below 2. Reverberations thermal layers 3. Multiple echoes 4. All of the above 3-71. Before you place the AN/UQN-1 Learning Objective: Discuss depth sounder in a transmitting thn depth sounder, including mode of operation, you should its use and operational allow it to warm up in standby characteristics. for a minimum period of 1.10 seconds 2. 20 seconds 3-66. For what purprse is the AN/UQN-1 3. 30 seconds designed, ane, what operating 4.60 seconds principle does it use? 1. To determine target depth by 3-72. Depressing the mark button on the solving a right triangle formula, AN/UQN-1 depth sounder causes a using slant range and depression 1. single pulse of sound energy angle to be transmitted 2. To determine depth of the sea 2. bright spot to appear on the by bouncing sound pulses off the scope bottom of the sea 3. solid circle to appear around 3. To determine target bearing by the scope's edge monitoring target noise 4. solid line to appear on the 4. To record target range by chart for record purposes marking chemically treated paper 3-73. What are the two modes of sound transmission (keying) provided by the AN/UQN-1? 1. AUTOMATIC and SINGLE PING 2. MARK and RECORD 3. AUTOMATIC and MARK 4. RECORD and SINGLE PING

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216 Assignment 4

Principles of Sonar (continued); BasicFire Control; Communications

Textbook, NAVEDTRA 10130-C: Pages 104 thru 136

4-4. In what sequence does the magnetic Learning Objective: Discuss tape in the AN/UNQ-7 pass the three the tape recorder, including magnetic heads during the RECORD its use and operational charac- mode of operation? teristics. 1. Erase, record, reproduce 2. Erase, reproduce, record 3. Reproduce, record, erase 4-1. What are the sound inputs to each of 4. Reproduce, erase, record the tracks of the AN/UNQ-7? 1. Both tracks are fed underwater 4-5. What happens to the tapewhen the sound information. erase head of an AN/UNQ-7 recorder 2. One track is connected to the is energized? sonar equipment; the other 1. The top track is erased andupon records sound from the sonar rewinding the 1-ottom track is operator's station. erased. 3. Both tracks are fed information 2. Either the top or bottom track directly from the sonar equip- may be erased as selected. ment. 3. Either top or bottom or both 4. Both tracks record sound fromthe tracks may be erased as selected. sonar operator's station. 4. Both tracks are.always erased simultaneously. 4-2. The purpose of the microphonein the AN/UNQ-7 tape recorder is to 4-4;. What is one reason thatyou should 1. transfer the electrical sound record critical sonar information signals onto the tape at 15 inches per second when you 2. convert the magnetic soundenergy are recording with the AN/UNQ-7? on the tape to electrical sound 1. To use as little tape as possible energy 2. To permit later analysis at lower 3. convert sound waves in the airto speeds electrical sound energy 3. To decrease the number of 4. increase the strength of the unwanted noises recorded magnetic field on the tape 4. To permit later analysis at higher speed 4-3. What is a material calledthat is capable of being made easily magnetic 4-7.What tape speed should be used for and is also able to lose its magnet- a high-quality recording? ism easily? 1. 3 3/4 1. Antimagnetic 2.7 1/2 2. Diffusible 3. 15 3. Permeable 4. Any of the above 4. Sensitive

217 22 4-8. The record safety interlock switch 4-12. Which of the following main ele- on the AN/UNQ-7 prevents ments of a fire control system 1. obtaining an electrical shock receives target data from sonar? while working on the recorder 1. Stabilization computer 2. obtaining an electrical shock 2. Attack console while threading the recorder 3. Positive indicator 3. accidental recording from the 4. Relay transmitter remote control unit 4. accidental recording at the 4-13. Which of the following puts out main unit corrections to own ship's course? 1. Attack console 4-9. While you are playing a tape on the 2. Positive indicator AN/UNQ-7 tape recorder, someone 3. Relay transmitter places the toggle switch on the 4. Stabilization computer remote control unit to RECORD. What will happen and why? 4-14. Which piece of equipment allows 1. The tape will continue to play the commanding officer to approve back because the record inter- the payload selection? lock is not engaged. 1. Attack console 2. The tape will continue to play 2. Position indicator back because reproduce takes 3. Relay transmitter precedence over record. 4. Stabilization computer 3. The tape will be erased because the record interlock is engaged. 4. The tape will be erased because record takes precedence over Learning Objective: Identify reproduce. the ASW weapons used against submarines in today's Navy. 4-10. How is the operator at a remote control unit warned when there are 5 minutes or less of recording 4-15. What is the main shipboard weapon time remaining on the tape on the currently used for action against AN/UNQ-7 recorder? submarines? 1.TheRECORDlampgoes out. 1. Stern dropped depth charge 2.TheRECORDlampflashes. 2. ASROC torpedo 3.TheSTANDBYlampgoes out. 3. Mk 32 time launched torpedo 4.TheSTANDBYlampflashes. 4. Lamps delivered depth charge 4-16. Modern antisubmarine torpedoes are better than early models because Learning Objective: Describe the newer torpedoes the major elements of a typical 1. go faster underwater fire control system. 2. go farther 3. are more maneuverable 4. have all of the above advantages 4-11. Fire control systems are used to 1. maintain target contact by using 4-17.A typical torpedo runs in what echo ranging sonar equipment type of pattern? 2. evaluate target-generated noise 1. Circle right to maintain sonar contact 2. Circle left 3. maintain contact by use of 3. Helical active and passive sonar equip- 4. Straight-running me:it 4. collect and translate informa- tion into weapon firing data

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218 4-18. All of the following torpedoes are 4-24. In analyzing target motion, the suitable for antisubmarine work surface sonar fire control system except must first combine sonar slant 1. straight-running contact range with the target's known or 2. active acoustic-homing estimated depth. By combining 3. passive acoustic-homing these two quantities, the system 4. wire-guided determines the 1. vertical range to the target 2. horizontal range to the target 3. target's course Learning Objective: Describe 4. target's speed the various phases used during the conduct of ASW. 4-25. Why is it desirable to stay as far away from an enemy submarine as possible and still maintain con- 4-19. Which of the following steps in the tact? destruction of a target is not 1. To obtain more accurate sonar ordinarily considered a part of information the fire control problem? 2. To obtain more accurate fire 1. Target detection control solution 2. Target tracking 3. To keep away from your own 3. Target movement analysis weapons 4. Ballistic computation 4. To keep the enemy from shooting at you 4-20. Both initial detection and tracking of a completely submerged submarine 4-26. Which of the following actions are commonly accomplished by would be considered part of the 1. visual sighting destruction phase of an ASW attack? 2. search radar 1. Any indirect action forcing a 3. sonar equipment submarine to surface 4. fire control computing equipment 2. The launching of an ASROC missile 4-21. Which of the following devices is 3. Use of the computed ballistic most likely to be used by a sub- solution marine in tracking a surface 4. All of the above actions target? 1. Sonobuoys 2. Passive sonar 3. Active sonar Learning Objective: Point out 4. Magnetic equipment the variables and fire control symbols used by fire control 4-22. The goal of the tracking phase of systems. the fire control problem is to accurately determine the target's 1. rate of relative motion 4-27. Which of the following variables 2. rate of descent would most likely cause a miss 3. course during an ASW attack? 4. speed 1. Own ship's course and speed change 4-23. A submarine's true course and speed 2. Target course and speed change is plotted on the dead-reckoning 3. Own ship's roll and pitch tracer by using information from 4. Target's roll and pitch 1. own ship's course 2. own ship's speed 4-28. The stable element is used in 3. sonar range and bearing fire control to correct variation 4. all of the above sources introduced by 1. changes in own ship's speed 2. changes in own ship's heading 3. own ship's roll and pitch 4. changes in target bearing 219

24 4-29. In which of the following planes 4-36. A magnetic brake uses electrical does the FC computer compute energy to solutions? 1. arrest or prevent movement of 1. Horizontal a rotating shaft 2. Vertical 2. resolve electrical vectors into 3. Deck line as components 4. All of the above 3. link two or more rotating shafts 4. transform rotation speeds 4-30. Which of the following references between shafts is used to measure the number of degrees between two vertical 4-37. Which of the following devices are planes? basically similar in their design 1. Relative bearing and construction but different in 2. Roll function? 3. Pitch 1. Magnetic clutch and electrical 4. Target depth resolver 2. Magnetic brake and magnetic 4-31. Detailed information on the new clutch system for underwater fire control 3. Electrical resolver and magnetic nomenclature is found in OP 1700, brake Volume 4. Electrical resolver and mechani- 1.1 cal integrator 2. 2 3. 3 4-38. Which trigonometric functions 4. 4 describe the output voltages pro- duced by an electrical resolver as 4-32. Which FC symbol represents the the rotor is turned? unmodified (basic) range from your 1. Sine and cosine ship to the target? 2. Tangent and cotangent 1. Rp 3. Secant and cosecant 2. Rv 4. Cosine and cotangent 3. Rh 4. R

4-33. What quantity is the result of Learning Objective: Describe correcting sonar measurements? the types of tests used to 1. Apparent target position maintain a modern FC computer. 2. Past target position 3. Actual target position 4. Future target position Use the following alternatives for items 4-39 thru 4-42: 4-34. The difference between past taret 1. Transmission test position and apparent target posi- 2. Static test tion is caused by 3. Dynamic test 1. sound beam refraction 4. Rate test 2. target movement 3. parallax 4-39. What fire control system test is 4. all of the above used to check the accuracy of a remote target angle indicator? 4-35. After target course, position, and speed have been detarmined, which 4-40. In what test would you manually of the following functions must be insert target bearing and course performed by the fire control to find target angle as a fixed system? value? 1. Estimating where the target will be when the weapon is delivered 4-41. What test is used to check the 2. Calculating what course to take accuracy of a computer time system? and when to fire 3. Sending all the required infor- 4-42. What systems test is used to check mation to the control and weapon the ability of a computer to stations correct an introduced error in a 4. Performing all of the above given time? functions

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220 4-43. In figure 4-13 of your textbook, 4-51. Target infornation for antisub- the diamond index on the inter- marine attacks is transmitted mediate ring dial of own ship's quickest by dial group indicates 1. sound-powered phones 1. own ship's course 2. repeaters 2. relative target bearing 3. MC circuits 3. true target bearing 4. voice tube 4. launcher train order 4-52. Video sonar information is dis- 4-44. By what method of internal com- played at a remote station by munication do the bridge personnel using receive initial sonar contact 1. electro-mechanical repeaters information? 2. dial display groups 1. Sound-powered phones 3. electronic azimuth-range indi- 2. Automatic indicator cators 3. Voice tube 4. MC circuits 4. MC system 4-53. The main advantage of radiotele- 0. Use the following alternatives phone over other types of external for items 4-45 thru 4-47: communications is its greater 1. 29MC 1. accuracy 2. 61JS 2. reliability 3. 21MC 3. security 4. 1JS 4. speed 4-45. What is the designation of the 4-54. Which of the following message antisubmarine attack team con- forms is most used by Sonar trol circuit? Technicians? 1. Plaindress 4-46. Which circuit is used to send con- 2. Abbreviated plaindress tact information until ASW stations 3. Codress are fully manned? 4. Abbreviated codress 4-47. What is the designation of the 4-55. What element of a message follows captain's command system? the call? 1. Heading 4-48. Which of the following sound 2. Text powered circuits is usually one 3. Ending way from sonar? 4. Reply 1. JA 2. JP 4-56. C,)ded tactical signals are used 3. 1JS to 4. 61JS 1. overcome language barriers 2. reduce chances of enemy interpretation 4-49. What feature on some MC units can 3. use less time in transmission the operator make use of to avoid 4. accomplish all of the above interfering with a circuit that is in use? 4-57. What brevity code word is used to 1. Cutout relay convey the meaning "This is the 2. Flashing light signals end of my message; no response is 3. Busy signal buzzers required"? 4. Monitor headsets 1. OVER 2. BREAK 4-50. Compared to sound-powered circuits, 3. OUT MC circuits have the disadvantage 4. OVER and OUT of 1. providing fewer separate circuit,7 2. increasing the general noise level 3. permitting only one-way opera- tion 4. requiring central operator con- trol 26

221 Learning Objective: Under- 4-63. The word "PROSIGN" stands for stand and make use of the 1. the first sign International Morse Code. 2. procedure sign 3. provisional signature 4. promissory signature 4-58. You should learn the Morse code using "dit" and "dah" sounds 4-64. What prosign is used to separate instead of "dot" and "dash" sounds the message text from the ending? because using "dits" and "dahs", 1. AR makes it easier for you to 2. BT 1. separate each individual sound 3. II 2. learn the sound patterns of each 4. TR letter 3. count the number of dits in each 4-65. What prosign is used to indicate character the word "from"? 4. count the beats in each charac- 1. AB ter 2. BT 3. DE 4-59 Where does the accent usually fall 4. WA in Morse code letters? 1. On the dit Information for items 4-66 thru 2. On the dah 4-70. Suppose your ship (NTLY) 3. On the first sound operating with her sister (NMTE) during 4. On the last sound an independent ship exercise (ISE) period. You have received permission 4-60. Which of the following practices to conduct a CW communication exercise may help a student to memorize with the sister ship over Gertrude. Morse code? First you establish communication to se 1. Writing the alphabet if the Sonar Technicians on the other 2. Speaking words in code ship are interested. These items refer 3. Visualizing the dits and dahs to some of the messages you might 4. Counting the dits and dahs transmit. individually 4-66. What is the first transmission 4-61. The Morse code sound is in the you make? short sound group for all of the 1. NMTE DE NTLY K following letters except 2. NMTE DE NTLY BT K 1. S 3. NTLY DE NMTE K 2. E 4. NTLY DE NMTE BT K 3. N 4. M 4-67. After you establish communication, your second message asking them 4-62. Which time interval should you if they are interested will be decrease to increase your code 1. NTLY DE DO YOU WISH COM DRILL practice speed? THIS NET BT K 1. Between characters 2. DE NTLY BT DO YOU WISH COM DRIL 2. For each character THIS NET K 3. Between words 3. NMTE NTLY DC YOU WISH COM DRILL 4. For each word THIS NET OVER 4. DE NTLY BT DO YOU WISH COM DRIL] THIS NET BT K

Learning Objective: Under- 4-68. Which of the following is a correcl stand the use of prosigns reply from your sister ship? and proper radiotelegraph 1. DE NMTE NT AFFIRMATIVE UT K procedures. 2. NMTE DE NT AFFIRMATIVE UT K 3. NTLY NMTE BT AFFIRMATIVE BT K 4. NTLY NMTE BT AFFIRMATIVE OVER

27 222 4-69. If, during the drill, you wished to 4-70. Later, to conclude the drill, pause for a few seconds to make an which of the following messages adjustment what prosign would you do yod send if you expect no use? reply? 1.AR 1.NMTE BT THANKS FOR DRILL OUT 2.IMI 2.NMTE BT THANKS FOR DRILL AR 3.BT 3.DE NTLY BT THANKS FOR DRILL 4.AS BT K 4.DE NTLY BT THANKS FOR DRILL BT AR

G44

28 Assignment

Communications (continued); Maintenance and Safety; Security

Textbook, NAVEDTRA 10130-C: Pages 136 thru 170

5-5. You have received and understood Learning Objective: Recognize WALRUS' last transmission. To prosigns and correct radio- acknowledge receipt, you should telephone procedures. reply 1. ROGER - OVER 2. ROGER WALRUS - OVER AND OUT 5-1. The adjusting screws on the sides 3. OK WALRUS - BLUEBIRD IS OFF of an unshielded telegraph key are AND CLEAR adjusted to 4. THIS IS BLUEBIRD - ROGER - OUT 1. prevent the key's movement sideways 5-6. If you make an error in transmit- 2. prevent the key's movement ting a message, you should identif up and down the correct version with 3. provide correct spring tension 1. SAY AGAIN 4. provide correct spacing between 2. CORRECTION the contacts 3. BREAK 4. DISREGARD THIS TRANSMISSION 5-2. All of the following are correct procedures for using a telegraph 5-7. Which of the following prowords key except should you send if a substantial 1. grasping the key tightly delay is necessary during commu- 2. resting your fingers lightly nication with another radio- on the key knob telephone station? 3. placing your thumb against the 1. WAIT side of the knob 2. STANDBY 4. placing your forefinger on the 3. QRX key top 4. WAIT OUT

5-3. What communication procedure should 5-8. You have just received a long you use when operating the under- message, the last few words of water telephone? which were obscured by interfer- 1. Sound-powered phone procedure ence. Which of the following 2. MC communication procedure replies that you might use conforms 3. Radiotelephone procedure to standard procedure? 4. Any of the preceding three 1. ROGER - BUT REPEAT LAST TEN WORE procedures 2. CORRECTION - SAY AGAIN 3. SAY AGAIN - ALL AFTER AIRBORNE 5-4. Which of the following calls and 4. ROGER - REPEAT BACK LAST TEN endings illustrate proper radio- WORDS telephone calling procedure? 1. BLUEBIRD CALLING WALRUS - GO AHEAD WALRUS 2. WALRUS - THIS IS BLUEBIRD - OVER 3. WALRUS DE BLUEBIRD - KAY 4. WALRUS - BLUEBIRD CALLING - OVER

29

224 5-9. Which of the following submarine 5-16. When you have disconnected and equipments is used for emergency tagged the sonar equipment main underwater communications? power switch, which of the follow- 1. AN/HQC-1 ing circuits may still be 2. AN/WQC-1 energized? 3. AN/UQC-1 1. Remote indicators 4. Radiotelephone 2. Heater elements 3. Synchros 4. All of the above circuits Learning Objective: Identify the various flares used for 5-17. When you go to close a switch you communications. have previously tagged and find another OPEN tag on it, what should you do? Use the following alternatives 1. Close the switch, and remove for items 5-10 thru 5-12. your tag only. 1. Green 2. Close the switch, and remove 2. White both tags. 3. Red 3. Leave the switch open, but 4. Yellow remove your tag. 4. Leave the switch open, and 5-10. What color of flare is used to remove both tag:, indicate the submarine has simulated firing? 5-18- When two people in the same space are working on energized circuits, 5-11. If a submarine intends to surface, which of the following qualifica- he should fire what color of flare? tions should each have? 1. Ability to secure the power 5-12. What color flare would NOT be used 2. Ability to give artificial under normal conditions? respiration 3. Ability to perform first aid 5-13. Which of the following publications for shock contains detailed information about 4. All of the above qualifications pyrotechnic signals? 1. ATP-1 5-19. Which of the following devices 2. NWIP 1-4 generally are used to discharge 3. AXP-1 capacitors in deenergized equip- 4. FXP-1 ment? 1. Grounding straps 2. Interlocks Learning Objective: Describe 3. Rubber gloves the safety precautions to be 4. Shorting bars observed when using or working on electrical or electronic 5-20. Electrical potential between equip- equipment. ment frames and the ship's hull is prevented by using 1. ground straps 5-14. Which of the following voltages 2. shock mountings often is treated with indifference 3. interlocks and is, therefore, the principal 4. shorting bars cause of electrical fatalities? 1. 600 5-21. When replacing blown fuses, observe 2. 440 the following safety precaution(s) 3. 220 1. Secure power when practical 4. 115 2. Use only proper fuse puller 3. Replace fuse with one of same 5-15. An index of Navy safety precautions rating applicable to the operating forces 4. All the above afloat is contained in 1. NAVSEA Technical Manual 2. NAVSEA 0967-000-0130 3. NAVSO P-2455 4. OPNAV NOTICE 5100.19

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225 5-22. What do you do to damaged power Learning Objective: Explain tool cords to make them safe? the operation of the test 1. Wrap with rubber tape. equipment used in testing and 2. Wrap with friction tape. troubleshooting sonar equipment. 3. Shorten to remove the damaged section. 4. Replace the cord. 5-28. What general purpose instrument may you use to avoid carrying 5-23. Test equipment should be at the several others? same ground level as the equipment 1. Megohmeter being measured to prevent erro- 2. Multimeter neous readings and 3. Ohmmeter 1. electrical hazards 4. Voltmeter 2. damage to test equipment 3. damage to equipment being tested 5-29. Which of the following instrumonts 4. capacitive reactance may be used to measure frequency? 1. Multimeter 5-24. Tube testers and other portable, 2. Voltmeter externally-powered test equipment 3. Oscilloscope are grounded to the ship's hull 4. Megohmeter by the use of 1. grounding straps 5-30. Transistors and diodes can be 2. three wire electrical cords and thoroughly checked by which of the connectors following? 3. shorting bars 1. AN/URM-127 4. probes 2. AN/USM-206 3. AN/USM-207 5-25. While you and STG3 Smith are working 4. AN/PSM-4D on the equipment, Smith makes contact with an electrical circuit and cannot let go. Nearby, a Learning Objective: Describe peacoat is lying on an aluminum the testing and troubleshooting chair and you are wearing a web procedures necessary for logical belt. Which of these three articles and accurate test and repair of might you use to remove Smith from sonar equipment. the circuit if you could not easily secure main power? 1. The chair or the peacoat 5-31. At what step in the troubleshooting 2. The chair or your web belt procedure in figure 9-9 of the 3. The peacoat or your web belt textbook would you first use a 4. Any of the three articles multimeter? 1. One 5-26. In the process of treating a person 2. Two who is not breathing as a result 3. Three of electrical shock, you might 4. Four perform all the following acts except to 5-32. Which of the following terminal 1. loosen his collar board markings indicate the second 2. give him morphine board in the fourth unit of the 3. give him artificial respiration equipment? 4. cover him with a blanket 1. TB 1402 2. TB 1420 5-27. The most important factor when you 3. TB 402 administer artificial respiration 4. TB 420 is to 1. use the mouth-to-mouth method 2. use the back pressure, arm lift method 3. begin treatment immediately 4. call a corpsman

31

226 5-33.What markings do you use on each 5-40.The principal use of a potentio- end of a conductor that connects meter in a circuit is to terminal E6 of board TB 802 to 1. vary voltage terminal C8 of board TB 202? 2. vary current 1. E6-202-C8/C8-802-E6 3. open and close the circuit 2. C8-202-E6/E6-802-C8 4. control motor speed 3. C8-202-E6jE6-202-C8 4. C8-802-E6/E6-802-C8

5-34.Where do you attach cable identi- cation tags? 1. Close to each terminal connection BLACK VIOLET GREEN 2. On the cable at 50 foot intervals 3. On either side of decks and 0 bulkheads BLUE BLACK RED 4. At all of the above locations

5-35.Where do you find a complete list of cable designations? 1. Manufacturer's Technical Manuals Figure 5A.-Fixed capacitor. 2. Handbook of Test Methods and Practices Refer to figure 9-14 in your text- 3. Dictionary of Standard Terminal book and figure 5A in this course Designations for Electronic for items 5-41 thru 5-43. Equipment 4. NAVSEA Technical Manual; 5-41.What is the value in micro- Chapter 9600 microfarads of the capacitor shown in figure 5A? 5-36.A 100 ohm resistor with a silver 1. 500 band may vary in resistance within 2. 600 minimum and maximum values of 3. 750 1. 95 and 105 ohms 4. 7,500 2. 90 and 110 ohms 3. 85 and 115 ohms 5-42.What is the minimum and maximum 4. 80 and 120 ohms capacitance, in micromicrofarads, allowed for the capacitor shown 5-37.What function does a rheostat in figure 5A? normally perform in a circuit? 1. 600 to 900 1. Voltage variation 2. 750 to 775 2. Current adjustment 3. 6,000 to 7,500 3. Open the circuit 4. 6,000 to 9,000 4. Close the circuit 5-43.What dielectric is used in the 5-38.A variable resistor intended for capacitor shown in figure 5A? use as a rheostat may frequently 1. Air be distinguished from one intended 2. Clay for use as a potentiometer by the 3. Mica 1. number of terminals 4. Graphite 2. color code marking 3. type of knob 5-44.What tolerance is allowed for a 4. length of the resistor element capacitor that has three dot code markings? 5-39.The continuity of rheostats and 1. 2% potentiometers is usually tested 2. 5% by using a/an 3. 10% 1. ammeter 4. 20% .2. voltmeter 3. ohmmeter 4. wattmeter

27 32 Learning Objective: Explain 5-51. A means of collecting maintenance the types of maintenance and and supply data in a form suitable how each is used to keep sonar for machine processing is provided equipment operational. by 1. PMS 2. MDCS 5-45. Which of the following publications 3. MIP concerning equipment operating 4. OPNAVINST 4790.4 standards are used to assist in carrying out a maintenance 111-ogram? 5-52. The MIP frequency code which 1. Manufacturer's Technical Manuals 2. NAVSEA Technical Manual identifies actions that arise only during specific situations is 3. Electronic Information Bulletin 1. A 4. 3-M Manual 2. C 3. R 4. S In items 5-46 thru 5-49, select from column B the type of maintenance 5-53. Who is responsible for updating described in column A. the quarterly schedule? 1. Department head A..Work B. Type of Performed 2. Division officer Maintenance 3. Leading petty officer 4. 3-M coordinator 5-46. The Sonar 1. Operational Technician on 5-54. An MRC does NOT list which ofthe watch replaces 2. Preventive following? an indicator lamp. 1. Tools, parts and materials 3. Corrective 2. Brief description of maintenance 5-47. The sonar watch required 4. Operational 3. Safety precautions to be section cleans or Preventive the air filters observed while the sonar 4. Location of equipment gear is in a 5-55. Which form is designed for standby situation. reporting discrepancies or 5-48. A weak vacuum suggested improvements in PMS? 1. OPNAV 4790/7B tube is replaced 2. OPNAV 4790/2K during a system 3. OPNAVINST 4790.4 check. 4. All the above 5-49. The senior Sonar Technician adjusts a relay that has Learning Objective: Be caused an equipment familiar with the definitions of the major elements of failure. security.

5-50. The Standard Navy Maintenance and 5-56. What attitude should guide Material Management (3-M) System naval does which of the following? personnel in safeguarding classi- fied information? 1. Prescribes standard maintenance procedures 1. All personnel should refrain from disseminating information 2. Provides feedback forprogram updating about security requirements. 3. Replaces all other maintenance 2. All personnel should make programs security of classified infor- 4. All the above mation a natural element in all tasks. 3. All personnel should think of security as a function separate from their daily tasks. 4. Only personnel with security clearances should concern themselves with security 33 requirements. 228 is assigned to 5-57. An instruction indicating the 5-63. What classification classification, downgrading, and mobilization plans of the United declassification guidance that may States? be assigned to subjects within a given to specific area of defense activity 5-64. What classification is information which if disclosed is defined as diplo- 1. classified information could lead to a break in 2. classification matic relation affecting the 3. classification guide defense of the United States? 4. classified material 5-65. Which classification isassigned related to 5-58. An individual who determines that to devices and material official information is in sub- communication security? stance the same as information 5-66. Which classification isassigned known by him to be already classi- such fied by the government as Top to materials having a nature that its unauthorized disclosure Secret, Secret, or Confidential defense and designates it accordingly is could be prejudicial to the known as a/an interests of the United States? 1. competent authority 5-67. According to the text,which of 2. commanding officer the following pieces of information 3. custodian 4. classifier is most likely to be classified as Secret? 5-59. Formerly Restricted Data is so 1. Documents concerning disci- designated by which of the plinary action, the knowledge following? of which is to be safeguarded 1. Atomic Energy Commission 2. Frequency and call sign 2. Department of Defense allocations 3. Both 1 and 2 above 3. An important intelligence 4. Secretary of the Navy operation 4. Security investigations of 5-60. Into which of the following naval officers categories is classified infor- mation divided? 1. Secret, Confidential, and Learning Objective: Define Restricted Data the different types of security 2. Top Secret, Secret, and For areas. Official Use Only 3. Confidential, Secret, and Top do Secret 5-68. Which of the following has to 4. Confidential, For Official Use with "Physical Security"? Only, and Secret 1. Transmission 2. Destruction The following alternatives are for 3. Custody items 5-61 thru 5-66. 4. All the above 1. Secret uncontrolled 2. Top Secret 5-69. An area which permits 3. Confidential movement of personnel is known as 4. Restricted Data 1. a limited area 2. an exclusion area 5-61. What classification isassigned to 3. a controlled area matrrial the unauthorized disclosure 4. any of the above of which could result in excep- tionally grave damage to the United States? 5-62. Which classification is appliedto material of such a nature that its unauthorized disclosure could damage the Nation? 229

34 Learning Objective: State 5-73. Who, if anyone, in the the requirements of maintaining Navy is security of keys and combina- allowed access tn classified tions. information by virtue of his rank? 1. Admirals 2. Captains 3. Both 1 and 2 above 5-70. When must the keys or combinations 4. None to safes or locks be changed? 1. Every 12 months 5-74. Which of the following 2. When a person with knowledge of topics must them is transferred not be mentioned in personal letters? 3. When a compromise issuspected 4. When any of the above 1. Casualties to personnelor occur material by enemy action 2. Location, identification, 5-71. How many complete turns ofa lock or is required to secure a safe? movement of ships or aircraft 1. At least two 3. Criticism of equipmentor morale 2. At least three of the United Statesor her 3. At least four allies 4. At least five 4. All of the above topics 5-75. When using thermalcopy paper to Learning Objective: Be reproduce classified information, familiar with the parameters what type thermal copy isused? of "Personal Security." 1. Front coated 2. Back coated 3. Uncoated 4. Any of the above 5-72. Those persons whoare entitled to have or know about classified material are those who have 1. the proper clearance 2. achieved the rank oflieutenant 3. a "need to know" 4. both 1 and 3 above

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