INSTITUTE FOR TELECOMMUNICATION SCIENCES OF THE NATIONAL TELECOMMUNICATIONS AND INFORMATION ADMINISTRATION
ANNUAL TECHNICAL PROGRESS REPORT 1979 For the period from Oct. 1, 1978 through Sept. 30, 1979 U.S. DEPARTMENT OF COMMERCE
National Telecommunications and Information Administration
-·-
ADMINISTRATOR Henry Geller
DEPUTY ADMINISTRATOR Edward Zimmerman
DEPUTY ADMINISTRATOR FOR OPERATIONS Stanley Cohn
OFFICE OF PLANNING & POLICY COORDINATION
Samuel Williams Act'g Dep. Dir.
I
OFFICEI OF OFFICEI OF OFFICEI OF OFFICE OF CONGRESSIONALI THE CHIEF COUNSEL INTERNATIONAL AFFAIRS ADM IN !STRATI 0 N & PUBLIC AFFAIRS
Gregg Skall, Chief Counsel Veronica Ahern, Director Cloyd Dodson, Director William Garrison Director
OFFICE OF OFFICE OF FEDERAL SYSTEMS INSTITUTE FOR OFFICE OF POLICY TELECOMMUNICATIONSI I I & DEVELOPMENT ANALYSIS I & SPECTRUM MANAGEMENT TELECOMMUNICATION SCIENCES APPLICATIONS Dale Hatfield William Lucas Donald Jansky Douglass Crombie, Associate Admin. Associate Administrator Forrest Chisman Associate Administrator Associate Administrator William Utlaut. Dep. Associate Admin. Dep. Assoc. Administrator ITS ANNUAL TECHNICAL PROGRESS REPORT 1979
For the period October 1, 1978 through Sept. 30, 1979
U.S. DEPARTMENT OF COMMERCE Juanita M. Kreps, Secretary
Henry Geller. Assistant Secretary for Communications and Information
TABLE OF CONTENTS
PAGE
LIST OF FIGURES v
LIST OF TABLES ix
INTRODUCTION 1
CHAPTER 1. EFFICIENT USE OF THE SPECTRUM 3
SECTION 1.1. SPECTRUM ENGINEERING TECHNIQUES 3
SECTION 1.2. SPECTRUM ENGINEERING FOR EFFICIENT SPECTRUM USE 21
SECTION 1.3. ADVANCED INSTRUMENTATION AND SPECTRUM MEASUREHENTS 35
SECTION 1.4. DETERMINATION OF SPECTRUM CONSUMING PROPERTIES 47
CHAPTER 2. SYSTEMS ENGINEERING AND EVALUATION 61
SECTION 2.1. COMMUNICATION SYSTEMS AND SERVICES ENGINEERING 61
SECTION 2.2; SATELLITE COMMUNICATIONS 84
SECTION 2.3. TERRESTRIAL RADIO SYSTEM PERFORMANCE 85
SECTION 2.4. SIMULATION AND STANDARDS 90
SECTION 2.5. FIBER OPTIC COMMUNICATIONS 91
CHAPTER 3. EM WAVE TRANSMISS ION 97
SECTION 3.1. WAVE TRANSMISSION CHARACTERISTICS 97
SECTION 3.2. CHARACTERISTICS OF THE TRANSMISSION MEDIA 99
3.2.1. Atmospheric Characteristics 99
3.2.2. Ionospheric Characteristics and Effects 113
SECTION 3. 3. DEVELOPMENT AND IMPLEMEN'rATION OF EM WAVE 115 TRANSMISS ION MODELS
3.3.1. Atmospheric Transmission Models 115
3.3.2. Ionospheric Transmission Models 119
SECTION 3.4. PREDICTION OF TRANSMISSION PARAMETERS. AND 127 SYSTEM PERFORMANCE
3.4.1. Long-Term Ionospheric Predictions 127
3.4.2. Medium Frequencies Transmission Studies 129
SECTION 3.5. APPLICATIONS 132
3.5.1. Antennas and Radiation 132
3.5.2. Transmission Through the Atmosphere: Applications 137
3.5.3. CCIR participation 149
ANNEX I. ITS PROJECTS FOR FY 79 153
ANNEX II. ORGANIZATIONAL DIRECTORY 155
ANNEX III. ALPHABETICAL LISTING OF ITS EMPLOYEES 157 ANNEX IV . ITS PUBLICATIONS FOR FISCAL YEAR 1979 159 ANNEX V. GENERAL AND HISTORICAL INFORMATION OF ITS 163
iii
LIST OF FIGURES
FIGURE TITLE PAGE
1-1 Coverage contours using FCC method. 5
1-2 Coverage contours using terrain correction . 6
1-3 Coverage contours (solid lines) and co-channel interference 7 contours (dashed lines) using FCC criteria
1-4 Coverage contours (solid lines) and co-channel interference 8 contours (dashed lines) using terrain correction .
1-5 Coverage contours (solid lines) and co-channel interference 9 contours (dashed lines) using terrain correction and a directional antenna for the Bakersfield facility.
1-6 Grade B coverage from licensed and planned (CP) TV stations . 11
1-7 United States paths . A scatter plot showing measured values 13 of g versus frequency for all over land paths with d greater 10 e than 80 km . Y (10) is obtained from the CCIR curves for a continental tegperate climate .
1-8 United States paths . Running medians of g versus frequency . 14 1 0 Each median uses .31 points from Figure 1, and the bars show an approximately 10% to 90% confidence interval .
1-9 Separation distance d versus d that is required to prevent 15 ss FM interference to an FM , land mobile system from a 10 MHz SS system at 150 MHz .
1-10 Power density , ILS . This graph predicts power density on the 17 ILS localizer front course. In other directions , the predictions should be adjusted according to the localizer 's horizontal antenna pattern.
1- 11 Signal ratio contours, ILS . 18
1-12 Orientation , ILS . Facility separation needed to obtain a D/U 19 of 23 dB for a time availability of 95 percent is provided as a function of undesired (ordinate) and desired (line code) course line angles.
1-13 Interference limited coverage estimates for instrument landing 20 systems (ILS ) .
1-14 Comparison of measured and predicted received signal level , 22 ground-to-air path .
1-15 Comparison of measured and predicted basic transmission loss , 23 point-to-point path .
1-16 Comparison of measured and predicted D/U ratios at an 24 aircraft for ground-based facilities .
1-17 Output format 25
1-18 Sample co-channel interference prediction for command/destruct 27 transmitters .
1-19 Plot or articulation score versus signal-to-interference ratio 28 with FM transmitter interfering with a digital receiver tuned 20 kHz below the digital transmitter. The points represent measured data , and the solid line represents a least squares fit to the data .
1-20 Measurements for city D. 30
v FIGURE TITLE � · 1-21 Measurements for city K . 31
1-22 Simulated ship positions and shore stations for the Atlantic area. 32
1-23 Simulated ship positions and shore stations for the Pacific area •. 32
1-24 The indicated bearing error for ADF receiver A as a function of 34 the undesired-to-desired ratio. The desired signal level is 500 vV/m at 200 kHz . The parameter oh the graph is the frequency separation of thg two signals and the difference in the direction of arrival is 90 •
1-25 Radio Spectrum Measurement System (RSMS ). 36
1-26 Block diagram of RSMS van . 37
1-27 Coverage from RSMS site ip Washington , o.c. , 162-174 MHz band . 40 _ 1-28 Block diagram , tower extension cable driver All. 43
1-29 Front panel of DM-4. 45
1-30 Block diagram of DM-4 . 46
1-31 Photograph of one of the upgraded field systems with spectrum 48 analyzer.
1-32 Expected received power, normalized to power received by a half-wave 50 length dipole antenna, for four typical types of home TV receiving antenna systems when the power flow is 1 W/m at the antenna .
1-33 Map of the Chicago-Peoria area where the home TV receiving 52 antenna system measurements will be made .
1-34 Conceptual diagram of TV performance model. 53
1-35 Selectivity of a TV receiver as measured at the second 54 detector output .
1-36 Photographs of TV performance measurements. 55
1-37 The automatic , optical tracking system . The elevation axis 56 over azimuth axis, continuous rotation pedestal with zoom lens op tical subsystem is on the top . The rack of control and display equipment is on the bottom .
1-38 Measured performance of an FM receiver with a single FM interferer 58
1-39 Measured performance of an FM receiver with three equal 59 amp litude interferers .
2-1 Federal Standard 1033 parameter development approach . 63
2-2 Selected access parameters . 64
2-3 EMS telecommun ications subsystems . 70
2-4 Emergency system processes . 70
2-5 EMSS me ssage routing . 72
2-6 Criteria development proj ect overview . 76
2-7 User requirements analysis concept . 77
2-8 Potential signaling interfaces to access area digital switch 78 for transitional network environment .
vi li'IGURE 'J;'ITLE ·PAGE
2-9 Local and remoted components of a switching hub . 79
2-10 Implementation concept for digital concentration, multiplexing, 81 switching, and transmission in the access area.
2-11 Interconnection of functional units for a typical area signal center . 82
2-12 Delegation of responsibilities. 83
2-13 Digital European Backbone System, Phase I. 86
2-14 Sample enhanced fault alarm system displays. 87
2-15 Status of FED-STD-1037, Vocabulary for Telecommunications. 92
2-16 Status of glossary on optical fiber waveguide communications . 95
3-1 Effects of path/antenna geometry on received signal with phase 98 interference by one ground-reflected component . Amplitude of resultant signal: R; envelope of maxima and minima: FE ; fading range: RF·. Abscissa is ratio of depression angle of reflection point to antenna beamwidth .
3-2 Profile of Radio Building/SAO Tower for k = 4/3 showing diffraction 100 ridge .
3-3 Ray tracing for layer with ducting gradient of -471 N/km . 100
3-4 Example of measured data at 28.8 GHz compared with results 101 expected from knife-edge diffraction theory .
3-5 Molecular (ma inly o ) attenuation rates at four height levels 102 2 between 0 and 30 km for medium {R . H. = 50%) humidity .
3-6 An example of the power impulse response measured over a 100 mile 104 troposcatter path in southern Arizona . The log response function shows received power spread to delays of 0.4 �s beyond the initial response.
3-7 Photograph of measurement path from transmitter to crest 106 (about 60 meters) .
3-8 Photograph of receiving terminal. 106
3-9 Examples of clear , well-defined paths . 108
3-10 Results for an obstacle having a radius of curvature from 0 to 1.0. 109
3-11 Normalized results for path 6, 9.6 GHz . 109
3- 12 Results for path 6, 28 .8 GHz . 110
3-13 Comparison of measured alarm probability (9 .6 GHz, decision 110 threshold at optimum) with two theoretical alarm probabilities.
3-14 Diffraction results . 111
3-15 Ray trace showing first-Fresnel ellipsoid for Radio Building/ 112 Erie path.
3-16 Examples of ionograms for the Salisbury, Australia, to Alamosa, 114 Colorado, path with (right side) and without (left side) the artificial ionospheric scatterer.
3-17 Average global behavior in the topside ionosphere of the HF radio 116 environment at local dawn for 12 MHz during the period September November 1977 . Contours are given in millivolts x lo-1 2880K .
vii FIGURE TITLE PAGE
3-18 Path locations for the long path 15 GHz multipath fading tests . 118
3-19 A block diagram of the data recording system used in the wide-band 120 measurements .
3-20 A sample of the questions and answers . 121
3-21 A sample of the information in the header , data , and trailer records . 122
3-22 Chart to estimate time of compatible operation between the fixed 124 service and a broadcast transmitter operating at 9.6 MHz.
3-23 Sample graph wh ich could be used to assist in the selection of a 124 theoretically optimum aeronautical channel.
3-24 Coverage area of the CONUS OTH-B radar system . 125
3-25 Typical rece ived audio and video signal variations of Channel 9 125 (KBTV) measured at a mobile speed of 20 mph between 2.5 and 3.5 miles from the transmitter in Golden , Colorado .
3-26 Cumulative probability distributions for the Channel 9 (KBTV) 126 signal on a Rayleigh scale.
3-27 Cumulative probability distributions for the Channel 9 (KBTV) 128 signal on a Gaussian scale .
3-28 San Clemente Island over-the-horizon radar antenna . 133
3-29 Current operating position/transmitter relationships . 135
3-30 Proposed operating position/transmitter relationships showing 135 the use of slow-tune (ST) and quick tune (QT ) transmitters .
3-31 Recommended manual matrix. 136
3-32 Recommended automatic matrix . 136
3-33 Strong fields (40 dB and more above the long-term median of 0 dBm) 138 that occur on transhorizon paths in association with elevated atmospheric (refractivity) layers as potential interference fields .
3-34 Contours of R (0 .1%) , the t = 1 min rainfall rates in mm/hr 139 1 predicted for 0.1 percent of an average year in the U.S.A.
3-35 Contours of s (0.l%) , the standard deviation in mm/hr of the 140 R1 year-to-year variation in the t = 1 min rainfall rate , R (0.l%) , for 0.1 percent of all hour s of a year . 1 3-36 Illustration of the possible effects of the operation of the SPS 141 on the ionosphere and telecommunications systems .
3-37 Gain versus angle from boresight . On-axis gain is about 87 .65 dB . 143
3-38 SPS single satellite power density distribution , mw/cm2 . 143 2 3-39 Field intensity distribution , mw/cm , 5 receiver sites. 144
3-40 Field intensity distribution for 10 SPS receiving sites . 145 2 3-41 Field intensity distr ibution , mw/cm , 10 receiver sites . 146
3-42 SPS results - electromagnetic compatibility effect of �1PTS beam 147 on M-W communications links.
3-43 SPS results - electromagnetic compatibility effect of HPTS beam 147 on security systems (hi-resolution TV & IR sensors) .
viii .FIGURE TITLE PAGE
3-44 SPS results - electromagnetic compatib ility effect of HPTS beam 148 on microprocessor accuracy .
3-45 Potential victim satellites . 150
3-46 The SPS amplitude thresho lds for GEO satellites. 150
3-47 SPS microwave beam geometry at Navstar orbit amplitude 151
3-48 SPS functional impact modes. 151
---LIST OF TABLES
TABLE
1-1 Total Area and Population Covered by at Least Grade B TV 10 Service and with Obj ectionable Cochannel Interference
1-2 Operational Range in Present 40 Channels for Three Cases 26 Described in Text
1-3 Summary of Measurement Results and Extracted Data for Horne TV 49 Receiving Antenna System Components
2-1 Blocking Estimates for Green Thumb Test 68
2-2 Characteristics of Mature Final EMSS Candidate 72
3-1 Transmitter Antenna Configurations 129
3-2 Proposed 9 kHz Frequency Allocation Plan 131
ix INTRODUCTION applicable basic knowledge of EM propagation. During FY 1979, a significant change in the organization of ITS was effected. Division 4 Advanced Communication This was the formation of a fourth Networks Division, Advanced Communications Networks, under the leadership of Conducts the technical p(ogram in Dr. McManamon. Because the reorganiza support of NTIA's responsibilities tion occurred late in the year, the body for telecommunication protection; of this progress report is prepared investigates technology alternatives around the work of the three original for development of competitive, Divisions. Thus the work of the new lower cost, communication networks Division is reported in Chapter 2. The providing improved services and roles of the four ITS Divisions, reflect better resource utilization; and ing this change, are outlined below. conducts research and analysis of advanced networks incorporating Division Functional Descriptions technical, economic, market, regula tory, and policy factors in an inte Division 1 Spectrum Utilization grated fashion.
Develops knowledge to more inten The work of all the Divisions is comple sively use the capacity of the mentary and interactive, supporting NTIA electromagnetic spectrum to meet User, Industry, and Resource activities, rapidly growing communications as well as solving problems for other demands by Government, industry, and Federal agencies. the public. The Division conducts a selective program·of research direc Significant accomplishments in the last ted toward obtaining more efficient year include: use of available spectrum resources, Integration of engineering and demo which is primarily related to inter graphic techniques for assessing the actions between radio systems and coverage of broadcasting facilities. the electromagnetic environment. The work involves measurement and Analysis of spread-spectrum tech evaluation of spectrum consuming niques for land-mobile radio showing properties of receivers, transmit that the new technique was less ters, antennas; spectrum occupancy; efficient in spectrum use than and development of spectrum planning conventional modulation methods. techniques and relates to NTIA roles in spectrum management. Measurements of the patterns of UHF and VHF TV receiving antennas to Division 2 Systems Technology and form part of a data base. Standards Acceptance of the ITS data commun Performs engineering studies which ications criteria as an interim result in user-oriented telecommuni Federal Standard (FS 1033) . cation performance criteria, and develops and applies measurement Use of the entropy concept for methods required for Federally or distinguishing between data commun publically operated systems. This ications and data processing. involves activities such as opera tions research, system architecture Continued support to u.s. Postal definitions, and system design and Service in the area of electronic evaluation. message systems.
Division 3 Applied Electromagnetic Studies on satellite communications, Science especially small earth terminal thin route systems. Obtains, develops, and evaluates atmospheric propagation character Support to u.s. Army in evaluation istics and develops models of these of Access Area Digital Switching characteristics applicable to com Systems. munication networks, system per formance predictions ahd .analysis, Contributions of the technical and for optimization of spectrum aspects of NTIA's role in tele use; maintains a library of ade communications protection. quately documented propagation models and disseminates and applies Completion and delivery to the u.s. these models to specific problems as Army at Ft. Huachuca of the first required. Work is both experimental two Transportable Automatic Electro and theoretical and relates to the magnetic Measurement Systems NTIA role of providing broadly (TAEMS). Reactivation of the Platteville high power HF transmitter for ionospheric scattering studies.
Support to Department of Energy's Satellite Power System studies in the areas of possible ionospheric modification and electromagnetic compatibility.
Responses to FCC Notices of Inquiry on AM stereo, TV drop-in methodol ogy, quadraphonic FM services, and improvements to TV service.
Significant technical contributions to NTIA's requests for rule making on FM services, and 9 kHz channel spacing in the MF broadcasting band.
These accomplishments show that, in addition to meeting our many commitments to other Federal agency sponsors in support of their national missions, we are becoming more fully integrated into NTIA by providing a technical basis for policy analysis and development. We look forward to growth in each of these areas.
2 time, and space is possible. They also CHAPTER 1. EFFICIENT USE OF address problems in optimum choice of THE SPECTRUM fr equencies and rational trade-offs ., between li mits on broad classes of equip_::.., ment (limits on factors such as antenna, The radio, or electromagnetic, spectrum height or power), the ab ility of a sy stem has seen dramatic growth in demand and to provide a required serv ice, and the use since the beginning of World War II. ef ficiency with which available spectrum Since that time, a great range of new is used. Techniques of this ki nd are spectrum-dependent services has evolved. ex tremely varied and must ad dr ess a wide American industry, government, and pri range of problems from the very specific vate citizens have put the spectrum to (for the designer of a specific system at work in such profusion that now satura a partic ular location) to the very tion appears imminent and, in some cases, general (for the policy maker and has already occurred. To provide for new regulator who must consider national or and expanded use, two major alternatives regional cons equences in a single exist. One is to exploit new regions of ac tion). the spectrum at progressively higher frequencies. The second is to provide Traditionally, spectrum engineering physical principles upon which spectrum techniques have been developed to use depends and, complementing this evaluate a specific situation, usually understanding, provide for more effec with a se ries of "safe" or "conservative" tive means of managing spectrum use. assumptions. Conservatism allowed for some simplicity in these techniques, but Spectrum use by the u.s. Government alone even so they were arcane enou gh so that is growing nine percent annually in those relatively few people used them, and even frequency regions where equipment is fewer unders tood them. readily available. Embryonic efforts are being made to use the even higher Our goals in this pa rt of the program are frequencies above 10 GHz where equipment to de velop a family of such techniques still remains to be developed for many that is based on a so und knowledge of the applications. physical ch aracteristics of the pr oblem, the technic al properties of equipment The National Telecommunications and involved, the practic al way in which that Information Administration, Institute for equipment is used, and the inf luence that Telecommunication Sciences (NTIA/ITS), Mother Nature brings to bear. If we are conducts a program of research and devel successful in developing such techniques, opment which addresses both of these they are,necessarily complex and, in alternatives. Much of the work being their initial form, di fficult to use and done to extend the use of the spectrum to understand. We are aggressively working higher frequencies is discussed in the to overcome these ba rriers to ef fective Electromagnetic Wave Tr ansmission chapter use by careful do cumentation and by of this rep ort . That chapter also pro de veloping computer methods that are vides brief mention of some of the work easily used and provide results in the being done to improve our understanding user's context. of propagation problems in those regions of the radio spectrum that are already Conservatism in many cases equates to extensively used. wasted spectrum. We address this problem by building techniques which incorporate In this chapter, .some highlights of the a comprehensive statistic al analysis of NTIA/ITS program directly concerned with the many variab le s (and their complex spectrum engineering are reviewed. Many interactions ) which affect the results. of these spectrum engineering projects By so doing, we allow the user to be as draw heavily on experience from other liberal or conservative as he ch ooses. programs in ITS, including antenna design and measurement, channel characterization For ov er a decade, government, academic, and system performance, and the many and industrial gr oups have ad vo cated propagation related efforts. de velopment of methods fo r improving the ov erall ef fectiveness of the use of the spectrum (as opposed to the op timization SECTION 1.1. SPECTRUM ENGINEERING of the performance of individual TECHNIQUES systems). This concern paralleled and even predated similar realizations that ideal common use of environmental We are concerned here with those techni resources such as air and water may not ques which can be used by policy makers, coincide with ec onomic maximization of an frequency managers, system designers and individual user's profits. planners, and others concerned with the use of spectrum dependent systems in the The developments reported here are in creasingly congested real world. These discussed with current ap plications in are techniques that define the extent to mind. But their tr ue value lies in their which realistic sharing of frequencies, general character. In most cases, these
3 methods can be adapted to meet many new broadcast station could be introd uced to requirements involving a broad range of the Bakersfield area which would not telecommunications needs and services . cause obj ectionable interference to the The presentation of summary results in Los Ang eles station . graphic form (partic ularly as maps and map overlays ), the development of demo TV Spectrum Planning Techniques is one of graphic results, the design of a series of pr oj ects cond ucted ov er the interactive computer programs that make last se veral years with the obj ective of it easy to ask "what if?" questions are pr oviding a range of planning tools that symptomatic of our-continuing effort to were both comprehensive and more valid bridge the gap between technology and the than has been available in the pa st . planners and policy makers . Much of the impetus for such work has come fr om an increasing concern in the The Re -Evaluation of Broadcast Freq uency FCC, NTIA, and other age ncies concerned Assi nment Criteria proJect goal has been wi th broadcasting matters for expanded to Iy establish the basis for more service, partic ularly of television . spe ctrum-efficient and service-oriented These concerns arise in nu merous contexts broad cast spectrum assignment criteria including the provision of initial considering antenna pa tterns, topography , service to rural areas, addi tiona! demography, and receiver characteristics, service in urban areas, comparability of and 2) develop and document user oriented UHF with VHF TV, and the expansion of computer programs for the application of educational TV. The most direct barrier su ch methodology, to such expans ion is the la ck of sui table frequency space . The following is an example of the pro ject's output . Current FCC reg u lations Our obj e ct�ves for this effort are proh ibit broadcast tr ansmitters being any several, and we il lustrate here our closer together than a spe cified distance approach and current progress to ward in ord er to limit interference . However, each, First,:planning techniques must the specified distance does not depend on al low comprehensive asse sments of TV the transmitters' power or he1ght charac service potential . Figure 1-6 is an teristics, their antenna patterns, or the example of service predictions for tele characteristics of the intervening ter vision stations currently operating in rain, all factors which could have a the u.s. as well as those under significant inf luence on red ucing separ constr uct ion . ations, thereby allowing additional servic e. In this example, an existing A se cond obj ective is to present results broad cast tr ansmitter in Los Angeles ·of complex analyses in terms easil y operates with an effe ctive radiated power interpretab le by a wide range of (ERP ) of 158 kilowatts and a height above interested parties including many without average terrain (HAAT ) of 3055 feet . engineering ba ckgrounds . The use of Suppose a second transmitter were to computer graphics. techniques to prod uce operate on the same channel at map displays of this kind is one appr oach Bakersfield, a situation not permitted to this obj ective which has pr ov en very under existing ru les. The se cond station successful . would operate with less than maximum facilities (e .g ., ERP of 5 kilowatts and Third ly, we are concerned about pr oviding HAAT of 300 feet), Figure 1-1 shows analysis to ols that are meaningful to and signal coverage contours for the two usable by experts in those other disci stations . Using the current FCC method plines which contrib ute to telecommuni for computing signal coverage, Figure 1-2 cations planning and policy making . One shows the same signal contours . However, approach to this objective is the devel the effects of terrain on the contours opment of population estimates to go with has now been included . Using the FCC 's maps of this kind . A wide range of criteria for co-channel interference, population statistic s are developed for Figure 1-3 shows the rural grade signal service estimates of the kind shown here . service-contours (s olid lines ) and the Pop ulation patterns can be anal yzed in co-channel interference contours (dashed urban and rural conte xts, populatio n lines ) for the two stations . The areas receiving varying degrees of se rvice, which are cross -hatched receive obj ec etc . These resu lts are prepared using tionable interference from the co-channel ITS developed methodology that pr ovides a transmitter . Figure 1-4 shows the rural unique integration of engineering esti grade and interference contours when the mates (of field strength, for example ) effects of terrain on the signal propa and population distributions . gation are included . Finally, a directional antenna is ad ded to the A further obj ective is to rational ly Bakersfield facility to give better characteriz e the real world, partic ularly coverage to the Bakersfield area . The the wide variability in rad io coverage res ults are shown in Figure 1-5 . experienced in practice . To this end, Table 1-1 summariz es the area-and popu statistic al me thods have been developed latlon-coverage results . The wh ich al low consideratio n of these calculations indicate a same ch annel variations .
4 Figure 1-1 . Coverage contours using FCC method.
5 Figure 1-2 . Coverage contours using terrain correction .
6 Figure 1-3 . Coverage contours (solid lines) and co-channel interference contours (dashed lines) using FCC criteria.
7 .� ( '\
,...--·)--- /
Figure 1-4 . Coverage contours (soliq lines) and co-channel interference contours (dashed lines) using terrain correction.
8 Figure 1-5 . Coverage contours (solid lines) and co-channel interference contours (dashed lines) using terrain correction and a directional antenna for the Bakersfield facility .
9 Table l-1. Total Area and Population Covered by at Least Grade B TV Service and with Objectionable Cochannel Interference
Los Angeles Bakersfield
Grade B Cochannel Interference Grade B Cochannel Interference
Figure Area Population Area Population Area Population Area Population
------
( sq krn) (thousand) ( sq krn) (thousand) (sq krn) (thousand) ( sq krn) (thousand)
- - 3 I (FCC method 45856 9778 2448 11 2512 180 2240 147
I-' no terrain) C>
--4
(terrain 23216 9138 -0- -0- 1408 131 352 35
effects)
- -5
(terrain 23216 9138 -0- -0- 2064 161 560 24
effects and
directional
antenna) I I-' I-'
UHITE • NO SERVIC£ GREY AREAS INDICATE SERVICE FR� 1 OR IIJRE OR lllRE. AND OR lllRE , 3 5 STATIONS AS SHADING BECOI'fS DARKfR.
G.A. HUFFORD� HTJA/ITS PREPARED BY
(CP)_ TV' :s·tation�·. ;!;rom licensed and pl,annea; Figure 1-6 . Grade l3 coverage Objective number five is to provide ones , it is written in conformity with te chniques that al low policy makers , the ANSI Standard Fortran, and 1 hence , designers , and planners to evaluate a should be completel y portable between wide range of alternatives. The coverage machines . It is this implementation map technique (which we refer to as which we are now disseminating to the COMAP) al lows users to de fine such pu bli c on reque st . This standard fonn is alternatives . Some examples include now being incorporated in a nu mber of our evaluation of service for : television coverage arrl interf erence anal ys is te chniques . 1) educational stations only, A series of studies have been conducted 2) single networks , to examine the potential for more ef ficient use of spectrum for la nd mobile 3) proposed new stations , and rad io applications . In evaluating the potential role of new technolog y, ITS has 4) new technical regulations (such evaluated.Spread Spectrum Applications to as revised constraints �n Land-Mobi le Radio . The possibility of maximum antenna heights . overl aying a spread-spe ctrum system into frequency bands containing conventional A si xth objective is the development of FM land-mobi le radio systems was estimates for improved technical examined . Overlaying here means the accurac y. In this conte xt , we have unrestricted operation of spread-spectrum asse mbled "long term" radio data into a and FM mo biles throughout a give n servic e computer-readable form . This present ar ea and on the same freq uencies . The collection contains time variability systems thus must rel y on the di f ferences statistics for about 1000 fixed paths . in modulation and spe.ctrum characteristic It is , however , stil l in a somewhat to minimiz.e interference . The pr oj ect primitive form , and we ca nnot , for examines interf erence between sy stems for example , use it in any very satisfa ctory fre 12 IIi I( " I( 2 I( X I( I( 'I( .. I( X - I( X I( I I. J Ill c I( I( � I( .. I I( I � I( I( . II XI .. II u I( I •• • I( � •• lt. • I( I( X • I .. Ill x• .. � I I ..� II I I( X • I I( • I ' I I( I I( I� Ijx l( lrll I • I l I( . , • I( I i • r • I I( "l I I ( I( I' • II I • I 20 50 100 200 500 2 5 10 Frequency In MHz and GHz Figure 1-7 . United States paths . A scatter plot showing measured values of g versus frequency for all over land paths 10 with d greater than 80 km . (_10) is obtained from e Y0 the CCIR curves for a continental temperate climate . 13 2 l 5 10 Frequency in MHz and GHz Figure 1-8 . United States paths . Running medians of g versus 10 frequency . Each median uses 3� points from Figure 1, and the bars show an approximately 10% to 90% confidence interval . 14 SS Base Interference to FM Base - Propagation Dependent []� Base Interference to FM Base - Highly Probable � SS Base (Mobile) Interference to FM Mobile (Base)- Propagation Dependent [Sj SS SS Base (Mobile) Interference to FM Mobile (Base) - Highly Probable E .><: c 0 +- 0..... 0 Cl. 10 Q) en en en (f) (f) "'0 10 100 dFM, FM Path Length ( km) Separation distance d versus d that is required Figure 1-9. 88 FM to prevent interference to an FM, land mobile system from a 10 MH z SS system at 150 MHz . 15 Wideband Signals," Purdue Un iversity either sing le-sideband or double-s ide band Report TR-EE 77-12p "Spe ctral Ef ficiency transmissions . Interleaved ch annel s were in Cellular Land-Mobile Commun ic ations : not put ad jacent to Channel s 9 or 19, or A Spread-Spectrum Approach ," Purdue Un i be tween ch annel s assigned to the ve rs ity Report TR-EE 78-44) is basical ly Citizen's Band and ch annel s ass igned to a freque ncy-hopped , time-encoded system . other se rvices. This resulted in 31 Individual use rs are distingui shed by a interleaved ch annel s--an increase of 7 5% . part icular time-freque ncy code , and al l However , cal cu lations show that the users have ins tant ac cess to the ch annel number of use rs ac hieving a specified at al l time s . Di sabling interference gr ade of se rv ice would onl y be increased from a mobile close to the ba se station by 20% to 30%. is avo ided by controlling the power of each mobi le so that al l signals arr iving The increase in users is not proportional at the ba se station have the same power. to the increase in ch annel s becau se of Coope r and Nettleton (1978) calculate adjacent channel interference . The cri that such a spread-spectrum sys tem would tical parameter is neither the ad jacent be about twice as efficient (that is , channel rejection of the receive rs nor allow about twice as many users pe r unit the ou t-of-channel radiation of the bandwid th per unit area ) as channel ized tr ansmitters . Ra ther , ft is the rel a FM small cell sys tems such as proposed by tively loose frequency tolerance of the Bell Telephone . They had earlier cla imed center freq uency of the emissions . This larger improvement in efficiency (Cooper to lerance is large enou gh that some of and Nettle ton, 1977 ), but they now the in-channel power of the transmitter be lieve those claims were based on ov er is within the pa ssband of the receive r in simplified calcula tions . enough cases to cause tr ouble some interf erence . Even these cla ims are se nsitive to the chosen propagation model . For A knowledge of se rv ice and interference attenuation rates observed on pa ths ranges associated.with ex isting and greater than 30 km long , the spe ctrum future air naviga tion aids is an efficiency of the two sys tems reve rses , impo rtant pa rt of the FAA' s spectrum with some doubt about the ad vantage of planning effort . Coverage , interference , spread spectrum on pa ths 10-30 km long . and propagation prediction capabili ties Thus , the cla imed advantage ·for the developed by NTIA as part of the Air spread spectrum sys tem is for very smal l Navi�ation Aids pr oj ect are util ized to ce lls, i.e., very high usage . prov 1de much of this informa tion . Cooper and Nettle ton compute that the ir Du ring 1971-1973 , an air/ground propa system (in one conf iguration ) al lows ga tion model ap plicable to irregular about 160 users per cell (Table 7.2 of terrain was developed by ITS fo r the FAA Cooper and Nettleton , 19 78 ). This has and was documented in de tail . This IF-73 significant implications for the dynamic (ITS-FAA-1973 ) propagation mode l has range required for the power control evolved into the IF-77 model , wh ic h is attenuator . Assume that there are n applicable to air/ground , air/air , users spread randomly over a circular ground/satellite , and air/satel li te coverage area . (The coverage areas are paths . It can al so be used for ground/ said to be he xagons , but a circle is an ground paths that are line-of-sight, ad equate approx imation .) If the smooth earth , or have a commo n ho rizon . attenuator is to have adequa te dynamic Techniques developed in this proj ect range for 99% of the time , then the al low a wide range of cove rage and required dynamic range is between 60 and interference situations to be evalua ted 80 dB , and should be accurate with 1 dB . for aeronautical services . Air/ground commun ic ations aeronautical naviga tion , This may be only a lower bound to the and surve il lance se rv ices are al l treated req ui red dynamic range of the attenua tor , by this capability. Representative be cause it is based on med ian result s are shown in Figures 1-10 through transmission loss, and does not ac count 1-13, although the existing capab ility for location variability. Since the near al lows the product ion of a broad range of transmitter is more likely to have a free se rv ice estima tes . space pa th than the far transmitter , the location variability could add 10 to As pa rt of a continuing effort to be tter 20 dB to the requi red dynamic range of unde rs taoo and impr ove the rel iability of the power control . spe ctrum planning techn ique s of this ki nd , ITS has reported on research wh ic h In the other study in th is project, the prov id es ex tens ive comparisons of increase in number of users resulting me asured propaga tion da ta with pr ed ic from interleaving ch annel s was computed . tions made by the IF-77 and othe r The specific example was a proposal propagation models . Al though IF-77 was be fore the Federal Commun ic ations developed for aeronautical applications , Commission to insert a single-sideband as me ntioned above , it can be used for ch annel between the present Citizen's some point-to-point propaga tion pa ths, Band channels, wh ich can be used for and the measured da ta se lected for 16 Rwft Ctdt 77/07/19. 11.1!.21. ll.S LOCALIZER ...... F""' .,.,, ElRP d8W F"''�"'"' y 110. ,.I 24.0 '""'') 51. H 5.5 ft(l.68m)fss S.eeth .. rth 1 lalddltl 501. ft (1905.:n}ms1 Peleriutltft HtriUIIttl H2 �50. n ••• ,, !51. Distance in km 20 40 0 80 1o o 120 140 160 180 � 1 ·50 I & -•o t\ cr M ...... 31 -70 .... I �� ·m "0 � ...... ·· ···· ·80 · ····· ·•·· ····· c: · · ····· ·•···· '=·� ··· · ······-· ······ ...... ··•······•· � - � ····•·· 90 ··· - � ····· M � c: -100 � ., "U &.. -110 �� t:"--- ., a 0 � looo..1--- n.. ·120 �...... � R -150 �-- ·140 -150 . 0 10 20 10 •o 5o •o 10 80 90 100 Olstal\ce II\ 1\ Mi Figure 1-10. Power density , ILS. This graph predicts power density on the ILS localizer front course . In other directions , the predictions should be adjusted according to the localizer' s horizontal antenna pattern. 17 mi (176.km) Stat ion separat ion 95 . n Ruft Codt 77/0•/t3. t5. 32. t&. Vft dts i red fac i I i ty Des ired f ac iIity �. oo:: 'J!'J ift_dB ARRAY ...... 8-LOOP .. -3• Olld 8 MHz S0111e as des ired foe iIity EIRP 24. 0 dB\TJ 110. ------20 CHid 12 ft (l. 68m) fss HI 5.5 _, CHid 20 Polarizatioft Ho riZofttal I II II I II 0 CHid 23 De sired path distance in km 20 40 60 80 100 120 140 160 180 1 0 ...1. I ...1. - I I 3.0 - I I I - 9 � ! 0 I :I I I I I 2.5 I I I I I : I I I I I I � � I ! I 2.0 � I I I •r-1 I I I- I I ! I f m � ! "0 I i ::s I : I .jJ I I •r-1 I I , 1.5 .jJ I I .-1 I too lil I I . I ; . I I .jJ I 11-4 i : : lil I I H I : I I 1.0 u I l I H 3 � . •r-1 - I \ : , · / I . .•· ..X: - ' I .·· a ' •· L j · 2 "I \ . � , V I . ·· 0.5 \ , .·. L- \�\ . 1- , I / 1 I 1 I I , f I v I II - I� , / 1/ II 0 0 10 20 30 40 so &o .,, o eo 90 100 Desired path �ista�ce i� � Mi Figure l--11 , Signal ratio contours 1 ILS . 18 Code 77/07/22. 13. 41 . 44. D/U 23 dB for 95% Ru11 Ou i red focility V11 du i red foci]ity ...... 8-LOOP . o.d•3:1•f2o. ARRAY 30. H 1 5. 5 (1. 68m) fss i red ----- 150. •• OS du focility Gild f t So 180. H2 4500. ft (1372.m)msl GO. Gild liltIll I 90. Facility separation in km 2 0 40 60 80 100 120 140 160 180 200 220 240 1 • I • I • II' 3GO ., ,, ., � • r 330 I i' � v I ) en ; ' ., I I I � "U 300 /:I I I lr � .:: I I / I v ,,.. 270 i I I I ., ; ' (;_ I I ·. I · .. en 240 \ ' .:: �\ , ·. I 0 •. · . .. \ .· ' 21 0 , ., I ·. I · .:: 1\ I � � I '\ ·,_ 180 \ I \ ·.. ·. I 0 r.' ., . \ II' 150 I !' � I : ; ' ) :.7 I I / 0 120 I u I I I. /,.t" I I 7 1.' "U 90 7/i ,: ., I I I· � I . ' ;· . I I ·. I · . II' GO ., \ '\, I "U \ ' ·. .:: 30 ,�. :> '\. I I � 1\ I \\ ·. I :. ' I 10 20 30 40 50 &0�\ . 70 80 \90 1 0 0 110 120 130 140 Facility seporot iol\ il\ 1\ Mi Figure 1-12 . Orientation, ILS . Facility separation needed to obtain a D/U of 23 dB for a time availability of 95 percent is provided as a function of undesired (ordinate) and desired (line code ) course line angles . 19 Ra tio: 2. 7910&/07. 17.26. 02. 95. 00 1. DIU d8W R�a11 Code �� �red fac lllt!l \Jadtt I red facI 11 t!l -s-t otloa...... ltPor otloa Ia a •I 10 •d 50 ILS LOCAL20.IZER0 110. tt-lz ----- 20 dBW S.. 01 dts lred lac illt!l •d &o EIRPG I t 70 Ht 7. 0 50 •d Po lorobo�t zot s�arlloft actHorlz o11 tot 80 I c ecce cu 40 •d 20 c .... c ', .... I • ( I ( .... 18 ic ( : 0 ( I • . c I c ( , 1\ • • I ic '0 t S c I t: . 0 I •• I , 14 I \ I ::J : ' ( ( . 0 ' 1\ i -lT .J: • .... ' • 12 • : ! t: ' I - "' 1 I '• I ., tO \ ' t I '0 • ' . 1\ : I ir ::J ' ' I .... 8 ( r ' .... ' . I - ; :• 0 s \ t : .... I ': T .... I � . I 0 4 ·. I I &. � I j ' u ·, &. I � ; ' 2 I I c(' : , c : • � I ' ,i : • ' ) D o � to 15 20 25 n AD 45 �J �5 -;o Des i red poth dlstoftce 1ft ft al Figure 1-13 . Interference limi ted coverage estimates for instrument landing systems (ILS) , 20 comparison include s both type s of pa ths. Examples of the se comparisons are shown SECTION 1.2. SPECTRUM ENG INEERING in Figu res 1-14, 1-15, and 1-16. FOR EF FICIENT SPECTRUM USE Figu re 1-16 is for a ground- to-air path , and Figure 1-16 involves a compa rison of de sired-to-undesired (D/U ) signal ratios In ad di tion to the development of new at an aircraft for ground-based de sired analytical and me asurement techn iques, and undesired facilities . Approx imately ITS ap elies the results of such work to 870,000 hours of data are associated with specif1c problems of concern to various the 242 paths used . Predictions made agencies . One important factor in with IF-77 were always best or second planning for new de velopments is our be st of the mode ls tested , and were sub ex perience with such proj ects whe re the stantially be tter than those made with - practical needs of operational age ncies me rely free space assumpt ions . The IF-77 mus t be recognized . model has a wide range of application and provides pred ictions compa tible with the CB Magaz ine recently petitioned the more speciali zed mode ls tested . Federal Commun ications Commission (FCC ) to expand the Citizen's Band Rad io The work currently underway on the Se rvice (CB) by adding 40 sing le-sideband project is in three directions : (SSB) ch annel s to the present 40 channel s wh ich can be used by SSB or dou ble 1. Production of computer sideband (DSB ) tr ansce ive rs . If the CB ge nerated propagation or is so expa nded , some ch annel s wil l be interference predictions for separated by 455 kHz or more and second the FAA is on an as-requested order intermodula tion interference will ba s is . Pa rt of th is work is be a possibility. In the pr oj ect CB being used by the FAA to Intermodula tion In terfe rence , ITS - develop new stand ards and to ca lculated the probability of such inter publish new handbooks . fe rence , wh ich is mo re impo rtant than the possibility. 2. The compa rison of predictions with expe rimental da ta and with A comput er model for calculating the othe r models is cons tantly probability distribut ion of signal -to go ing on . interfe rence ratio for quite general situa tions has been deve loped ov er the 3. New approaches to predictions last se veral years as a pa rt of the are be ing developed that spectrum engineering technique s deve lop invo lve ac tual geog raphic me nt effort . It ac cepts as input the station locations and the spatial di stribution of stations (random automatic use of a terrain data or de terministic ), the time and freq ue ncy file to obtain pa th prof ile di stributions of transmissions , and the information for various statistical di stributions of equipment aircraft pos itions . characteristics, propaga tion loss, and radio noi se . A proj ect to des ign and deve lop an interactive computer prog ram to ca lculate CB rad ios are made by many di fferent jammer-to-s ignal ratios for user-defined manu facturers , and have different suscep scenarios is be ing sponsored by the u.s. tibility to intermod ula tion interfe rence . Army Signal s Warfare Laborato ry . When The Probability distribut ion of implemented , the JAMME R program will. susceptibility was determined using al low the user to 1nvestigate the ef fects me asurements made by the FCC that chang ing va rious propagation and laboratories . sys tem pa rameters have on the jamme r- to signal ratios computed at se lected loca Model ing assumpt ions (described in more tions . JAMMER uses the ITS standard area de tail in NT IA Te ch nical Memo randum 79- prediction propagation mode l de ve l opep by 15) we re : Long ley and Rice (1968 ) and revised for stand ard applications th is year . The a) CB radios of inte res t are software design plan has been completed . distributed randomly ins ide a circle of 20 kM . Th is program can form the ba sis of a more generally applicable mobile commun ication b) Users distribute themse lves system de sign program. JAMMER' s fe atures un iforml y ove r the channel s. of prog ram portability, ease of inter active use , and ve rsatility of output , as c) Co-channel interferers have the shown in Figure 1-17 , cou ld allow a same ch aracteristics as the mo bi le sys tem deSigner to eas ily make wanted transmitter , but users trade-off studies of his sys tem of the new SSB ch annel s have parameters . ten time as much power on the ave rage . 21 Direction of Flight - .., 100,��Al titude�� Flown - ��-· 10,000 ft. Type of Aircraft - DC-3 Type of Facility - VOR A/C Loss between Antenna & Rec ---- Observed I F-77 Prediction 2 --- 5% • • • • • • • • • • 5 0 o/o --- 9 5% --- Increase in variability due to terrain refle ction . Increase in median level due to -·-++-+-·H-+ counterpoise re flection . 55 50 45 4o 35 30 25 ao 15 10 5 0 5 10 15 DISTANCE TO STATION IN NAUTICAL MILES Figure 1-14 . Comparison of measured and predicted received signal level , ground-to-air path . 22 HORNISGRINDE W GE R - DARMSTADT W GER PATHS 2363 TO 2366, 2440 TO 2443 "' Cit "' ... � -z z 0 --- ... � > "' ...J 80 "' GO PATHS 2363 2441 D = 142 6 km F-- 516 0 MHz 80 --- Obstrvtd 90 Prtd cttd: i ...... --- TN 1 0 1 "' 1 00 Ill ...... 0 ...... 1 970 ...J ...... 110 z � ...... - � 0 - . .. . - . Ill 120 - Ill • • - :a: - t- - - Ill F .S. 130 · - z �1 - � ... - Cit... � � ...... -· � _ 140 :-:-···· � � - u �::· - iii · • • · • � 150 ·· r--...... ·· . . . Ill · . . . � ····· . .. 1 · . 60 ·· . ··· . 1 70 1 1 99 99. 9 99. " . 0 1 • 0 so 90 - - 80 PATHS 2364 2442 D- 142 6 km F 547 0 MHz --- Obstrvtd 90 Prtd i c ttd : --- TN 1 0 1 Ill 1 00 Ill f-- ...... 0 ...... 1970 ...J ..... 110 z "' ...... 0 ...... Ill ...... 1 20 . Ill · - . ;: - Ill t-_ z 130 - F .S. � . . .. 2 . . . . . Cit . ... f.:.:.:: j . ... r- ...... - (, . 140 ��· ...... �···· - u- 1-- � ...... Ill � . • .. � 150 · r--._ • • .... ···· ...... Ill - . · . � . � ··· . ·· . 1 60 �p:...... ,_ . . 1 70 1 1 . 0 • 1 0 so 90 99 99. 9 99. " PERCENT T1 P1E Figure 1-15 . Comparison of measured and predicted basic tr ansmission loss, point-to-point path . 23 10 r tt IJ_ �1 ttjf f IT·I . - r . l � l L t I . 1 , . .j::! ..j 0 i . . + ' t!= � + it ' ' . ,J ! • • r + t ' IlI.l i -t , · Observed · - n + b l � -�-� � IF-77 Prediction i . - . ttuti: . • - l i1 r ++ . - . ... �f.!· .H �f.. t. rH' 5% -10 . . •••••••••• ! • ;.f.t f:tW Itt +ill L H 50% . J;-:r .• , }1J• 't f� e � +:+l:';· o c:> · , 9 50/1 ori tlhl s_p q 4[t lli t ,I'll n-tm m • ' · f1 c-e 4 . . ·nm 'fj + �rrtt . . 1m _. ':'Tt . - �f ���t+•+++•m.- • -20 :: rm 1. !ttl ori . ·, m�-n Ill i 1r rrm rmt1trm1111+++H+;.Im·' nHI !;j.t i � It-++ + . .ff. -8 , . : �:tt1H�. t;!!-it t-l=ttt ·f 0 . � • . t . � tt - . ·H. · ft ::'!i . ;t . :.!'\ p; ·r... ,·l trlt.:.r ; . E N iH tit _ f�r �� ' .p� . · . l1J1-!tw £ln ·I • . "'" . 11-±1 ' :,- .:..i.f .- ·t! . �- - .: 1: -l.H t r -30 0 . 'It "rfi -� i.' IT.. II!ih1n 'Fiori fitt� F•.� '!H ·m �_ ;.;·· • ... Ji � l ; �t��...l. !Il.:ti t!-!�t�tti. ::;t m.tr.�1 :: �r� nUJH't: t . ,. . �lr .· Jr l; �i . t -� ' ti t L ; . · # - r fWU�l tifl tttJ iri t-r j !J1� - ' 1 �f!fl} t rmw ·� � - � J.( HE!f . n rtf " T . l-: t-\i- ' --: -40 m1mtr r • iffi + f! ' 1 . li .. _ n t w �q ··. . ., tt ' T·t '! � ' 1 Jn• H t • " . . tl!! , - r ·tt ll . ··f l . t If- . ltftttlllHJrf!h r . fr r+�.. 1 � �- • 1 - · j: ht· - . l rtr ·r �- l�H: r fr �� ' ' . ,t£ : : 'l·.. 1 _ �'jgtt. - _.. , m Hf!. .. " t Ht �:�u + r � l!+ .. . r' t!!Tl : --r+ ...... H1l l t t�F H:t tt . tr: ·! t � · i ;pHr + .+ • -50 Desired Facility 11 � � . iF - VOR + fttl. itt -�H -1 · . Undesired Facility - LOC j" -t + �tn:rt;.: it ; :ttH;�.;: m,.� t tt u tt i �1 . ti . .... rtt ff; ffil �r?;�.!�. Altitude Flown ft . • • ttH ;ffi - 3,000 :j• t ·· .. : : rl IH+-H-1 t:f•l t H mm' .nTIOUIACi!: Figure 1-16 . Comparison of measured and predicted D/U ratios at an aircraft for ground-based facilities. Jammer Jammer Antenna Height Power (Meters) (dBW) 1 3 5 7 Jammer-to- Receiver Distance (Kilometers) 0.01 - 63 - 63 - 63 - 63 0. 0 5 - 5 6 - 57 - 5 8 - 58 0.1 - 4 9 - 5 1 - 52 - 5 3 0. 5 - 4 1 -44 - 4 6 -4 8 1.0 - 3 5 - 37 - 4 0 -4 2 5.0 - 26 - 30 - 33 - 36 10.0 - 17 - 22 - 26 -29 Figure l-17. Output format . 25 d) The channel plan proposed by CB most uncertain factor, rece ive r susc epti Magaz ine was used . This plan- bility to intermod ulation inte rference . has 24 pairs of channels In Case 3, the susceptibility of separated by 460 kHz, but none receivers to intermod ulation inte rfere nc e separated by 455 kHz. was increased by 13 dB, to its value for ch annel s sepa rated by 455 KHz. For th is e) Operation is in typical urban implausible case , the median ope rational radio noise . range is decreased by 25% , and the 90% ope rational range by 14%. f) Al l 24 pairs of channel s are contr ibut ing simultaneously to Bec ause Case 2 represents an uppe r bound intermod ulation interference . on the degrada tion from intermod ulation interference , we conclude that 40 g) SSB transmissions cause as much addi tional SSB-only channel s ad ded to the in te rmod ulation interference as CB band will result in le ss than 10% DS B tr ansmissions . de crease in med ian ope rational rang e eve n if the nu mber of use rs is doubled . Assumpt ions c), f), and g) are very con se rvative , making the calculated inter Propagation prediction capabilities ference an uppe r bound of that wh ich developed as a pa rt of the Air Nav igation would actually exist. Aids pr oj ect are fr equentl y ut il ized to provide predictions fo r ot her proj ects . Re sults are presented in terms of the One such pr oj ect is the Ground/A ir ope rational range , 0R (l7), wh ich is the Propaga tion Prediction proj ect in wh ich f range at which the signal -to-interference se rv ice coverage pr ed1ctions for a mis ratio is 17 dB or greater on 100% of the sile command/destruct tr ansmi tter were attempted ca lls . The ope rational range developed for the Pac ific Missile Te st for three cases is shown in Ta ble 1-2 . Cente r (PMTC ). These pred ictions we re Case 1 is the ba seline ca se wh1ch -- made with a program IOCldi fied to (1) inc lude s only the present 40 channel s approx imate the circularly po larized with no intermodulation interference . It transmitter antenna pa ttern and (2) is assumed that two CB rad ios are trans include missile receiving antenna gain mitting in the metropolitan area on each statistics fo r a random orienta tion in channel . One is the wanted transmitter the ca lculation of signal le ve l va ri and the other is an interferer . Many ability. Figure 1-18 is a sample of the channels in urban areas wil l have more predictions prov ided . It is ap plicable co-channel interferers than th is. The to the co-channel interference problem three columns are the range at which the associated with the simultaneou s ope r signal -to- interference ra tio is 17 dB for ation of tw o command/destruct tr ansmit 50% , 75%, and 90% of the attempted calls . ters and prov ides the de sired -to undesired (D/U ) signal radio ava ilable at Table 1-2 . Ope ra tional range in the mi�sile as a funct ion of unde sired present 40 channel s for three facility-to-missile distance . cases de scribed in tex t. The Spe ctrum Anal ys is Suppo rt proj ect prov 1des special anal yses, computations , Ope rational range , km and me asureme nts in the direct suppo rt of NTIA 's SMS pr ogram . Recentl y, the 0.5 o. 7 5 0. 90 Ju stic e and 'l'r easury Departme nts pur chased a large nu mb er of digi tal ly Case 1 5. 06 2.85 l. 59 encoded vo ice trans ceive rs fo r the ir la nd Case 2 4.74 2. 74 l. 55 mo bi le radio ap plications . The tr ans Case 3 3.84 2. 34 l. 37 ce ive rs prov ide se cure comm un ications links fo r the ir users , but, becau se of the mod ulation me thods used by the tr ans ce ive rs , they may cause interfe rence or Case 2 include s the 40 SSB-only channel s. be suscep tible to interference from othe r There are now twice as many users , with trans ce ivers in the land mo bi le ba nd . ha lf of them un i forml y di stributed in the Tests were conducted at ITS to de termine new channels. The ope rational range the digital trans ceivers ' pe rformance in shewn is th at for a DSB link in one of interference environments . Figure 1-19 the present 40 channels . Intermodula tion shows an example of the pe rformance--- interference has decreased the med ian measurement results with ar ticulation ope rational range by onl y 6%, and the 90% score vers us the input signal-to operational range by about 3%. Th is is a inte rference ratio . smal l price to pay for doubling the number of users , and will probably be The CATV Radiation Measurements pr oject , unnot iceable . unde r the sponsorship of the FCC, de ve loped a se ns itive meas ureme nt system Case 3 was an attempt to find the thr esh to measure levels of leakage fr om CATV old of a sign ificant ef fect , and to te st sys tems in the airspace ov er selected the se ns itivity of the res ults to the ci ties . The proj ect al so supported 26 Dtt l rtd dlttonct 1200. N MI Run Code 79/02120 . 1S. 15. 55. Ott lrtd foclllt Uadtt l rtd foc l llt y y ...... F'rtt ''ect PT ltJGU SAN DIEGO [ ,trl • 11. H1 1590. 0 ft obovt •• 1 H1 555.0 obovt •• l yp It [ahldltl 501. 500. n al obovt at l H2 500. n al obovt •• l H2 [ Jewtrl99. 91. F'rtttutncy l1S. f'tfz 50 - � lO J I 50 m v I "'0 ,/'\/ I I! 20 � I 7 0 __..� � 10 ) 0 ...... 1 . . ����-··· · ···- � ...... 0 /. �---} 0 I! Cf\ -10 / _,J , - :. ) -20 ' Cl -5 0 1-- -- -lO --- -,____ - 11 0 12 0 15 0 1' 0 �e c 15 0 tS 0 1700 18 0 1� 0 200 0 Samp le co-channel interference prediction for Figure 1-18. command/destruct transmitters . 27 .ao -'10.00 -30.00 -zoo SIGNAL.-TO...INTERFEAENCE ARTie (08) Figure 1-19 . Plot or articulation score versus signal-to-interference ratio with FM transmitter interfering with a digital receiver tuned 20 kHz below the digital transmitter . The points represent measured data , and the solid line represents a least squares fit to the data . consult ing and advisory services to the ope ration of cable systems in any of the FCC in the design of the measurements and freq uency bands . the analys is of the data . One facet of the ope ration of the Un i ted CATV systems tend to le ak some rf energy States Coast Guard is the Automated wh ich may then radiate , caus ing interfer Mutual-assistance Vessel Res cue (AMVER) ence to users of the rad io spectrum. The system. In this sy stem , ships of many FCC initiated an advisory committee di fferent flags vo luntarily se nd regular composed of members from the CATV rad io reports of the ir pos ition , course , commun ity, the manu facturers of cable speed , and search and rescue rel a ted equipment , seve ral Federal agencies capabilities (e.g., if they have a doctor including NTIA and the FAA , as well as aboard ). The se data, rece ived at the othe r interes ted parties . Th is ad visory various commun ic ation stations , are committee met several times providing stored on a comput er at the AM VE R center input to the FCC in a measureme nt effort on Gove rnor 's Island , New Yo rk . Then , in to de termine what levels of radiation the ev ent of an eme rgency at se a, such as might exist at seve ral al titudes above a a disab led or sink ing ship, an il l variety of CATV systems . The CATV crewman or passenger , or a plane down , systems to be measured were ch osen so these da ta can be rapidly retrieved in that both newly ins tal led sys tems and order to de termine wh ich ships are in the older, poorly mainta ined systems wou ld be vicinity that can give aid to the tes ted . stricken vessel or aircraft. Mos t of the se AM VER reports are hand led on the The ITS measurement system cons isted of a high-frequency (HF ) maritime bands us ing narrow band receive r with a -148 dBm Morse Code (cw) or in some ca se s sing le tangential sens itivity at the 118 MHz sideband (SSB) voice . test frequency; a computer controlled digitizer and real time analyzer; and a The purpose of the San Juan/Kodiak AMVER buffe red digital data recorde r. A stable Cove rage Al ternatives-s tu dy was to exa= cw oscillator source was connec ted into mine the commun lC atlon coverage regarding the cable system be ing tested , and the the AMVER reporting in tw o ocean reg ions level ad jus ted to that of the closest - one in the Atlantic and the other in operating video carrier . The measurement the Pacific . More specifical ly, this system was ins talled in a FAA aircraft study assessed the impact of dropping the and flown over the test cities in a grid AMVER guard at San Juan , Pu erto Rico , in pattern at up to three altitudes. These the Atlantic area and the guard at data were then recorded and returned to Kod iak, Alaska , in the Pacific area . ITS where the data were reduced into Further, a de te rmination was made of distribution plots of ampli tudes. wh ich ad di tional frequency bands must be guarded at other, existing commun ic ation An interes t ing compa rison of some of the stations to make up the coverage loss, if output plots is shown in Figure 1-20. any , due to droppi ng the above guards . Th is figure shows the levels me asured at one of the cities with the cw oscillator Analys is fo r th is pr oblem wa s based on a both on and of f. Th is city is a rel a se ries. of 469 assumed ship pos itions in tive ly small one away fr om any ma jor the Atlantic and Pacific oceans as shown me tropolitan areas . The signal received in Figures 1-22 and 1-23. Predictions of with the cw source off is due to ambient communic ation rel iab1l1ty fr om each of noise in the area . Th is was me asured to the shore stations to each of the ship have a mean level of -132 dBm. When the locations was made cons ide ring both sig cw source was tu rned on , the mean leve l nal le ve l ·and noi se statistics. Char increased to -112 dBm, indicating that acteristics of the tr ansmitters , their the CATV system caused a 20 dB increase antennas , and the ionos pheric trans in interference in the airspace . mission med ium we re al so cons. ide red using Figu re 1-21 shows a se cond city that is the ITS developed skywave prediction part of a major metropolitan area . In model known as HFMUFE S. th is city, an ambient level of -117 dBm level was me asured , and when the cw Re sults of th is anal ys is prov ide maps and source was energized, the increase in estimates of the pe rcent of ocean area mean level was less than 0,4 dB . We can cove red with at least a rel iability of draw the conclus ions that the city of 85% . The se data led to the fo l lowing Figure 1-20 has 15 dB le ss backgr ound conclusions : r adia tion-or noise in th is band wid th than the city of Figure 1-21, and the CATV Atlantic Area system of Figure 1-2T:ls a much be tter system from the stand point of leakage . • San Juan contr ib utes sign ificantl y to the coverage These da ta and others were analyzed and of the Atlantic area . Th is will be a pa rt of the final report of the contr ibution is especially ad visory commi ttee . These data will then important during time s of low be used by the FCC to de termine if any solar ac tivi ty and/or dur ing restrictions need to be placed on the the winter . 29 -. a: ...... • ...... 0. 0 •• ••• (1500 FT) (/,1 9 ...... j . . .;o . .. � ...... (/,1 . . • •• •••• 0 •• 0 ••••• )-1 .e ...... • • # 1 • 118 • MHz �� / / . 9 27 78 . . u . . DIPOLES (.") .7 ...... WITH SIGNRL/NO l'rl� a:w o o o o o o 0 o o o I I o •: o 0 o o o o I o o o o o o o o � o o o o o o o o o o 0 I o I o o o o o o 0 o o o o o 0 •:- o o o o o o I 0 o o o o o o o o o o 0 o o o o I o o o o 0 I o o o 0 0 0 o o o o o •> o o o o o o o I o o o 6 . ' . . . . � . . . . >-W ...... ; ...... : ...... : ...... :...... : ...... 1- w . 6 . . . . . t-l l:.,j . . . ;...... "'" ···············...... ············· ············ ...... 1 : ; ...... > 4 . . 0 • . _! X . . )-tw ...... ···········••\••·· ······· ...... , ...... o o o o I o o o o o o o • • o o o o o o o o o o o I o o o o o o o o o o o o o o o o 0 0 o o o o o o o o o o o 3 . . . . : � � . . . . o . !XI ...... 0:(.1) ...... 0 Oo ••••••0 0 0. · 0.0 0. 00.0 0 0.'· 0 ••00 ••• 0.... 0 0 ••• 0. 0 00 0 ••'· ··.oo 0 0. 000 ••·· •• 0 0 ••••• 0. 00••••• 0 0 ••••• · · •••••••••••··· 00•• \' •••••••• · 0 •••••••• 0 ••• • � : : � : : : �)-I 2 0 • 0 • 0 • • . . . . . • • • 0 .• • • 0 ...... · · · · · • · ·. · · · · · · •,,·, • · · · · • · · ·•·· · · • • · · · · · • I • · · ·. ·,,,.,,.· · .•• , •• ,,.•••• · , •••••••••, • • • • •••.•, , ••••• ••,,, •• ,,••• , · .,,,••• , ,, • , , • · · o o ,,••• o ••••• 11� 1 � } : � ·� � � 1 . · ...... 0...... 3 - -713 -6 -5 -1 () -1213 -1113 -1130 -913 813 13 0 -4 0 RECEI VED SIGN�L LEVEL CdBm l a: . . oooooooo•·············· ···········••o• ····· •• ••· ...... '' •••••• ·••••o·•····· : l : t (15 00 FTl . \ (,o) .9 (,o) ...... ••• •• 0 ••••••• 0 ... )-1 . � . ... � . . . .. # 1 118 MHz• �� .B ...... 9 /27 . 78 . 0 ...... : ...... _. � _ u ...... NO S I GNRL . . (/) . . . .7 ...... ! . : ...... L. . . _ ...... l'X't � . . 0 0 . '' ''0'''00'''. '0"'00'''''0'-••00•••••••ooo ··················••·•ooo ••o•··········· ·············· crw ·····o········: ·······•o••··· 1 : : : � . 6 . >-W ...... ooo 1-W. 6 t-1 u. 4 oooo•••OOoo•o•: O••o••oooooooo ...... J ...... o•··:·oo••••ooo•··· ···············: ·············· , 0 0 ...J ::'.: • . 0 t-tW . , 3 ...... o o o o o o o , o o o o o � o o , o o 0 o o o o , o o o o:. o o o o o 0 o o o o o o o o o :' 0 o o 0 0 o o o o I o o o o o o I o o o 0 0 o o o o o I � ...... CI: 0 . . o o o o o o o o o o o o o o o o o o o o o , , o o 0 o o o o I o o o o 0 o o 0 o o o o o o o o o o o o o o o o o o o o o • ; ; � . . . o o o o f.'l t-1 2 . . . • • 0 . . 0 ...... 00000000000000 ·······••••o••••o••·········· •••O••••o••·•· ·············· . .. 0 •••••• � · ••••••• '. 1 : :O l � ' 1 (.l...... - -6 - -1313 -1213 -1113 -11313 -913 ee -713 13 513 -413 RECEI VED SIGNRL LEVEL CdBm l Figure 1-20 . Measurements for city D. 30 cr • '.'•••••• ' ••• •••0 ' ••••••••• 1 ••••' ••••••• ' . <· ... ' ...' ...... ' ••••• .•. • ·i ...... •••..•.. -:·:( .....210•...... 0· .:· .. .•..•.....MSL) '.· : · ...... •• (.1) • 9 ...... (.1) . t-1 . e ...... �- ...... /. �.< ' . .�..1. . ..1. �.� . M .tl...... )?. ?..�...... :. _:. . l. !.._ ...... u • • 0 • • • • • ' ' • ' ' •••• ' ••.: .•••••••••••••• ••••••••••••• 0 : •• 0 ••••••••••••: ••••••••••••••• •••••••••••••• •••••••0 •••••• (I') • . � . .� �. ? . . . (.X.j . . . , . err-. . • • • . • . . • .•.•, •..•••.. 1 · •..••••.•..•.· :· •••.....••... � ...••.....•.•• � ...•, ••...... 6 ...... w ...... ;-,� ...... • • • 0 . . 5 . . . W ...... 1- ...... t-tW . 4 ··············i ··············l ···•·•oOO••o•·<•ooo••••·······:···············\ ·······o······ ...... J U . . 1-t : ) : . . . . . • 0 •••••••••••0 � •••••••••0 •••• ! . ... . 0 ••• ·:· ••••••• 0 ••• !XI w .3 ...... a: . . •••••0 •••••••• •••••••0. 0 •••• ; ••••• 0 •••• 0. I'YI (I') . 2 � Ot-t oooo••oo••O••<·······o•••oo•••: Oo······"'''' i� • . 1 . 0... RECEIVED SIGNRL LEVEL (dBm ) a: ...... ••••••••••••· · • • • • • • • ; ; � 0 • • • • 0 • • •�. • • • • • ; • • • ' ••• 0 • • • • ...... (15 00 FT ) .:,.·) .9 . (-":! ...... · ...... · · ...... ) t-1 • : � ...... 8 . . 118 MH ...... z ...... u . . 0 ••••••••0 ••• • • 0 . ... . • •••• •••••••• •• ••• • • • • • • 0 0.. •••••••••••••· - ••••••••• 0 •••• •••••••••••••• •••••••••••••• (.-') • 7 �-...... -�...... : : � : : : : . . . l'rl l=l ...... ••..., •···· ·········· ·· ····••••oooo ············· ...... a: Jo : \ ' ...... ' •.•..•... w .6 . . . . <· ...... : ...... :::1 i ...... '\' ...... ::- w .. • .. • .. : . 0 . . ········•o•oo••········••oooooo•··········· s ...... � ...... 1- W . ...... 1-t (j ;. · ···· ···· · ··· · :· ······· ······· ...... : ...... ! ):: .4 . . . �-tW ...... ······························ ·············· . . . : : ...... 3 . . l'l:! . . a: (.·') . • • • • • • • • • • • • • • • ••••••••' •••••: •••••••••••••••; •••••••• •••••• ••••••••• 0 ••• . �' 1Y1 ,...... 2 ...... 0 . . ··············· • > ··············:················: ·············· fl� 1 ...... 0...... 30 - 1 - Hl0 -90 -e0 -70 -60 -se -40 RECEIVED SIG NRL LEVEL CdBm) Figure 1-21. Measurements for city K. 31 \ ... \ ' .. . 'I .,.,.•• I • • \.I --- ·' • • • \. r ' \ • 1 ' " ' • . ' __ ' - ,. ' �,. ' ' - -·- r _ ... - � - . ' ' I ' • ·-' I ,. __ .. .. - -r I I I I I I ··,.·-·-1. I I . . I .' " . . . ' �... . . " ' I \ ..I . .' --- ' ...... '' . . . , .. \. . . " . \ '. . ' . . \ ' ' \ ------··------'�-'==--·----''------1------L------...... ;....----1 Figure 1-22. Simulated ship positions and shore stations for the Atlantic area , Figure 1-23 , Simulated ship positions and shore stations for the Pacific area . 32 • The mos t important frequencies Av iation Adm inistration initiated this at San Juan are 16 MH z dur ing study at the Institute to he lp answe r, at the day and 8 MH z at night; least, the fo llowing question : Do the 12 MH z contr ibutes ve ry little . powe r line ca rrier sys tems radiate suf ficient energy to prod uce sign ificant rad io compa ss errors ? • One alternative , if San Juan is dropped , is the addition of Early results of the ITS study estab 22 MH z during the day and 6 MH z lished that powe r li ne carrier radiation at night at Portsmouth . Th is is not eas ily pr edictable and , as a al te rnative is as good or cons equence , a measurement ef fort was be tter than San Juan except instituted . The PLC radiation measure during times of low solar me nts will be made using an FAA flight ac tivity in the day . inspection aircraft . The aircraf t will be eq uipped with a spectrum analyzer/data • Anothe r alternative to Sa n Juan record ing sys tem to make the requi red is to utilize Miami . The signal level me asurements . The aircraft highe r frequencies , 12 and and da ta sy stem are be ing supplied by th� 16 MHz , are be st during the day Na tional Av iation Facilities Ex perimental and the lower frequencies , 6 Center of the FAA. The measurements will and 8 MHz , are best at night , be made ov er power li nes of the Te nnessee It may be sufficient to use Valley Authority (TVA) . Seve ral li nes onl y 16 MH z in the day and 6 have be en chosen, representing a variety MH z at night . Th is cove rage of line lengths , subs tation canplex ity, may be inadequa te dur ing time s PLC coupling me thods , etc. These PLC of high sola r ac itivi ty , in radiation measureme nts are be ing flown as which case two frequencies of th is wr iting . The measureme nt pr ogram could be used . inc lude s cal ibration of the airborne receiving sys tem using carefully se lected Pa cific Area non-d irec t io nal be ac ons in Te xas and Oklahoma . Susceptibility me asurements of • Kod iak is a very ins ign ificant ADF receivers will al so be made at the contr ibutor to the coverage of FAA Ae ronautical Center in Oklahoma City. the Pac ific area . The fre Typical results of the me asurements are quencies currently in use at shown in Figure 1-24. Further work is San Francisco and Honolulu do planned to assess the ov eral l ef fe cts of an excellent job of cove ring powe r line ca rrier sys tems on ADF re the Pac ific area . ce ive rs based on the results ac qui red so far . The Power Line Carrier Interference project seeks to de term1ne the ex tent to Spectrum engineering is al so ac complished wh ich radio signal s intent ionally trans through a se ries of pr oj ects wh ich pro mitted along high-voltage power li nes can vide consulting services to othe r interfere with the prope r ope ration of age ncies of gove rnment . The u.s. Coast automatic direction find er (ADF ) rad io Guard Consulting proj ect provides "qu1 ck compa sses used for aeronautical naviga reaction" propagation predictions and tion . Carrier current systems are wide ly short-term studies as needed by the Coast used by power compa nies for commun ica Guard in the ope ration of the ir la rge tions us ing signal structures varying network of MF and HF commun ic ation from single pu lses for fau lt detection to systems . In ad di tion , four-times-a-year FSK mod ulation for remo te me tering and propaga tion predictions are supplied to control . SSB vo ice is often used for suppo rt · the AM VER (Automated Mu tual commun ications . The re is a tr end for assistance VEssel Re scue ) sy stem . These some ut il ities to use higher powe rs fo r pe riod ic predictions are distributed to the ir powe r line ca rrier sys tems so tha t the many AMVER pa rt ic ipa nts to aid them highe r freq uencies can be used ov er in ch oos ing the be st fr equency and Coast greater di stances . ADF radio compa sses Guard commun ic ation station with wh ic h to ope rate in the same frequency band . log the ir AMVER reports . The effects of PL C radiation on the ADF Mos t of the "qui ck reaction" propaga tion rad io compa ss sys tems are not wel l known . predictions are requested by and provided In fact, the degree to wh ich PLC sign al s to the communication stations directly. radiate is not wel l known . Some of the As one ex ample , this last year predic observed ADF errors have been correc tly tions for ci rcuits between San Francisco attr ibuted to PLC radiation; there have and Borneo were supplied to the San been some notable examples in Europe . Francisco commun ication station , Then , too , some of the observed ADF errors that have be en attr ibuted to PLC FAA/Technical Support in Propagation and radiation may , in fact , have been caused Spectral Eng ineering prov1des cons ult ing by re-radiation of the be acon signal by ac t1v1ty 1n support of the Spe ctrum the nearby power lines , Due to the above Management staf f of the Fede ral Av iation factors and unknowns , the Federal Ad ministration . The pr imary objective is 33 1,uv ) Undesired Signal Leve l ( dB/m 20 (f) (1) ,_(1) 0'1 (1) � ,_ f>,_ w w .1:> 0'1 c ,_ 0 (1) CD 16 Undesired to Desired Ratio (dB) Figure 1-24. The indicated bearing error for ADF receiver A a(:>· a function of th.e. unde:;; .j..red-to-desired ratio . The desired signal leve l is 500 �V/� at 200 kHz . The parameter on the graph is the frequency separation of the two signals and the difference in the direction of arrival is 90° . is to prov ide techn ical support on a Th is year marks the end of the first six quick-response bas is to questions that ye ars of operation of the RSMS , a sys tem may be relevant to the FAA in the World fully ded ica ted to ga thering me asurements Adm inistrative Radio Confe rence (WARC ) of the radio environme nt fo r frequency proceed ings. ma nageme nt purposes. The Canal Zone RF I Survey project In that time , the RSMS ha s continued to required an on-site visit to the Canal survey ge neral frequency usage in many Zone for the Panama Canal Company for the pa rts of the Un i ted States , as well as to select ion of a weathe r radar site from 15 participate in measurements aimed at possible cand ida tes . so lving a pa rt icular problem . Complete usage surveys have be en comple ted in A letter report was prepared and submit seven large me tropoli tan areas . These ted for a compromise site that was the surveys include me asureme nts in ab out a mo st logical and prac tical choice . dozen government mobi le and radar ba nds Recommendations were al so made for be tween 30 MH z and 12 GH z. ad ditional filtering in the radar trans mitter and the reu se of microwave radio In a typical operation , the RSM S will frequencies from the Atlantic side of the park at a se lected me asurement site communication/control link. (usually a hil l ov erlooking mo st of the metropolitan area ) making me asurements of Consultative serv ices were provided to one band at a time . When al l of the the National Wea the r Service of NOAA on band s have be en sufficiently me asured , problems related to Weathe r -----Radar the RSMS will le ave the site and move to Interference Surveys . another measurement location . In some ca ses, the earlier measureme nt will have An on-site visit was made to the AFOS ide ntif ied some tr ansmitters wh ich will computer sys tem at the Minne apolis, be measured in more de tail by moving the Minnesota , weathe r service of fice to RSMS close by and conduct ing coordinated inves tiga te and solve problems of the me asurements with the controlling age ncy . computer system. By the time that measureme nts in a ty p ical area are finished , a to tal of ab ou t Technical assistance was prov ided to 100 million me asureme nts have be en made KXMC-TV Channel 13, Minot , North Dakota , and processed into report ready graphs for an interference problem caused by and lis tings . S-band radar . The magn i tude of the job de scribed above SECTION 1.3. ADVANCED INSTRUMENTATION AND would clearly not be pr actical with SPECTRUM MEASUREME NTS manually-ope rated me asureme nt equipment . The RSMS was designed from the start as a computer-controlled me asur eme nt system . Ne ed s for more realistic est imates of how Prog rams written in BASI C control a the spectrum is really used ge nerate general -purpose spe ctrum anal yzer sys tem requirements for instrumentation that is (Figure 1-26 ). Frequencies between more accurate , faster , and more economi 100 kHz and 18 GH z can be tuned with syn cal. In some ca ses , the requirement is thesizer ac curacy. Measureme nt band for new types of me asurement and , to an widths between 10 Hz and 3 MH z can be increasing degree , large quantities of employed , along with peak de tection or data are required to allow rational sta video integrating , to tailor the sy s tem tistical analys is of characteristics that to the pa rticular measurement requi re vary widely. In such cases , there is an me nts . In ce rtain mobi le radio band s, a urgent need for da ta recorded in digital spe cial-purpose commun ication measureme nt form so that computer anal ys is is receiver (CMR ) prov ides ve ry wide dynamic pos sible . In th is section , we de scribe range and rectangula r ba ndpass character several kind s of instrumentation that istics wh ich are more sui ted to the share computer control and digital me as urement of channel ized commun ic ation record ing as common fe atures . The first ba nds . Specialized eq ui pment is al so group of instruments prov ide powerful , ava ilable fo r radar measurements , computer-controlled capabilities mounted including automa tic di rect ion-finding and in ve hicles for a variety of special pulse so rting techn iques . These uses . techniques permit more id eal me asureme nt of a single radar by isolating it fr om The second approach to instrumentation other radars sharing the same spectrum. provides a small package that is ve ry The whole system is des igned to calibrate portable , ope rates with a wide range of itself and to automa tical ly add existing equipment , and is relatively low appropriate cal ibration factors to the cost. me asureme nts as the measureme nt are be ing made . Interactive grap hics displays Pe rhaps the spectrum ins trumentation al low the ope rator to more eas ily fo llow development with the longest history at the course of the me asurement , and ITS is the Radio Spectrum Measurement numerous controls al low the ope rator Sys tem (RSMS ) (Figure 1-25 ), 35 Figure 1-25. Radio Spectrum Measurement System (RSMS) . 36 15 Antennas and Noise Diodes RF /VIDEO BLOCK DIAGRAM 0.03·12 GHz of RSMS VAN * Not Under Computer Control = ..... :z:: ..... = == ...... - = :z: :z:: == !:U":! COMMUNICATION * - -= CIQ ·= TEST RECEIVER <'.1- >- COMMUNICATION MEASUREMENT RECEIVER 0.5·12 GHz DETECTOR LOG VIDEO RF TUNER AMPLIFIER 10 MHz 0-18 GHz VIDEO BANDWIDTH * OSCILLOSCOPE * PRF FILTER WIDE BAND IF UNIT 0.01 ·300 kHz 3MHz SSB, AM, FM PULSE TRAIN LOG AMP 1 and 3M Hz BANDWIDTH IF DETECTORS SEPARATOR BANDWIDTHS in 1,3,10 STEPS LOG AMP TRANSIENT DIGITIZER 8 BITS, 10 nS 2000 BYTE MEMORY Gating Control L Digital Data to Computer Digital Data ..,____ to Computer &...;..;.....;.;.;..;;..:....:...;..t;;;.;..;...J Figure 1-26. Block diagram of RSMS van . 37 the threat radars do not include rece iv ation . Data is output to the aircraft 's ers which could be used to measure and home ba se fo r aircrew training proficien evaluate the airborne EC M responses . cy ratings and identification of mal func Instead , the AN/MSR-T l is ut ilized to tioning airborne ECM eq uipment . de termine the operational capability of the ECM sys tems and prov ide maintenance Air Force ac ceptance testing was com personnel with reliable and sufficient pleted in February 19 79 and was fo llowed data to identify mal functioning equip by extens ive user (SAC and TA C) Ope ra ment . tional Te st and Ev alua tion (OT&E) wh ich is sched uled for comple tion in Sep tembe r The prog ram was started in Feb ruary 1976. 1979. De sign ch anges and de ficiencies The multiple receiver de s ign was comple will be identified so that product ion ted in May 1977 after extens ive tes t ing specifications can be pr epared to ac qui re of new technologies for receivers (wide similar units fo r EW range deployment in band 0.5-18 GH z tuners with 500 MH z IF early 1980 . bandwidths ) and signal processors (500 MHz ba ndwidth Bragg cell op tical A second de riva t ive of the RSM S de velop techniques with 1 MH z freque ncy resolu me nt , the Air Force (TAC) Signal An al ys is tion ) wh ich were cons idered essential Sys tem , is being deve loped for the req ui rements for the firs t preproduction Tactical Air Comma nd , Tactical Fighter AN/MSR-Tl. Procureme nt was initiated and Weapons Center Ra nge Group (TFWC RG) , de live ry of al l hardware was comple ted in Nellis AFB, Nevada . The sy stem is to July 1978. Integration was comple ted in provide an interim electronic warfare Augus t 1978, and extens ive tes ting is now (EW) Signal Anal ys is Sys tem (SAS) capa unde rway at the USAF/SAC Strateg ic Train bility un til product ion un its of the ing Range (STR ) in La Junta , Colorado . AN /MSR-Tl become ava ilab le in the 1982 time fr ame . The interim SAS de sign is The ope rational frequency range . of the based upon port ions of the AN/MS R-T l. AN /MSR-Tl is .5-18 GH z. The system con sists of four 0.5-18 GH z rf tu ners (one Although the TA C/ SAS de sign is similar to with a 500 MHz IF ba ndwidth and three the AN /MSR-Tl, it will be deployed for with a 20 MHz IF ba ndwidth ), a spectrum diffe rent applications in el ectronic analyzer · re ceiver (3 MHz band-width ), warfare test and exerci se evaluation . appropriate demod ulations , signal proces Its pr imary application is the evalua tion sing units (Instantaneous Fourier Trans of Electronic Countermeasures (ECM ) em is form optical processor , microprocessors , sions from airborne fighter platforms computers , special function hardwired when stimula ted by widely spaced (several un its ), and data/display/s torage units . kilome ters ) ground-based acqui sition and All hardware is conf i gured in a se lf tracking radars . propelled ve hicle with non-d irectional and directional antennas mo un ted on the The sys tem is fully automa ted and is vehicle roof . The az imuth and elevation designed to cover the freque ncy range position of the directional antennas are 500 kHz to 18 GH z, and consists of anten computer controlled us ing slaved tracking nas , receive rs , computers, signal proces command s from a local threat IFF target sors , da ta display Is to rage un its, and trac king system. suppo rt eq uipment . It is ho used in a se lf-contained , sel f-propelled ve hicle The sys tem is fully automated and con with internal powe r sources fo r remo te tains extens ive so ftware fo r command and ope ration . The antenna sy stem include s control of al l units and me asurement/ an el ectro-optical television tr acke r anal ys is routines . ECM eq uipped air system to provide automa tic tracking of a craft, upon entry into the range de s ig targe t aircraf t at a range of 20-25 nau nated airspace , are subj ected to va rious tical miles . The rece ive r subsys tem con real istic threats wh ich are to be coun tains tw o receive r se ts . One is a tered by specific signals that are wideba nd tuner cove ring the range 500 MHz generated to jam or de ceive the threat 's to 18 GH z with a 500 MH z IF bandwidth and receiver and ope rator . Since the threats the se cond is a spe ctrum anal yzer receiv do not have receivers the AN/MSR-Tl is er covering the range 50 kHz to 18 GH z. employed to rece ive and analyze the The wideband tuner works with an IFT airborne response . The EC M signal s are op tical processor that has a 500 MHz evaluated by precise measurements of the instantaneous bandwidth and freque ncy time of response , frequency of response , resolut ion of 1 MH z. Its purpose is to and all signal characteristics . The scan or mon itor al l freque ncy bands of threat emissions and the ir effective interest to de tect onset time s of tr ans countermeasure signals are classified , missions which are to be measured . A but involve pulsed waveform pa tterns read-out is obtained indicating activity which produce range gate pu ll-off and and frequency fo r hand-off to the spe c ve locity ga te pu ll-off targe t deception trum anal yzer rece iver for de tail ed techn ique s as well as ba rrage and spot sign al processing of the de tected noi se jamm ing mo des . Airborne EC M emissions . sys tems are either manu al or automatic , depend ing on the aircraft's conf igur- 38 to vary the measurements ac cord ing to a point, be yond which a majority of the real-time measurement results . locations did not propagate enough signal to be received by the RSMS . The results As an example of the util ity of computer of this analysis were plot ted on a map of controlled systems to measure spectrum the Wash ing ton , DC , area (Figure 1-27 ). usage , cons i�er the measurement of mo bile Several contours were drawn : 1) dotted rad io channel usage . The RSMS (a) tu nes li nes show the area within which a precisely to a given channel center fre typ ical ba se station would be measured by quency; (b) makes a burs t of 40 me asure the RSMS during at leas t 90%. of the time me nts and processe s them to el iminate any it ac tual ly trans mi t ted , 2) ·solid lines impulsive noise ; (c) uses various show wh ere a ty pical base station calibration factors to conve rt the wou ld be seen at least 50% of the time , digital da ta to absolute power units of and 3) heavy dashed lines show where a typ dBm ; (d) compa res the final single value ical mobile transmitter would be received to a measureme nt threshold to de te rmine at least half of the time . We have also whethe r the signal is sys tem noise or a plot ted the pos itions of base station real signal ; (e) upda tes statistics for transmi tters assigned to this band on the tha t channel , showing the pe rcent of time map , wh ic h shows that mos t of the trans the channel is in use , the ave rage signal mi t ters are wi thin the areas of best level , and the max imum signal level ; and coverage . This me ans that the ty pical (f) de termines and tunes to the nex t ba se sta tion coverage is even be tter than channel to repeat the process . At the the geographic coverage . Cove rage to same time , another part of the sys tem is mobi le un its is less certain , but one testing for any ve ry large signal s in the would need much mo re da ta than is likely band wh ich could cau se intermod ula tion ; to be ava ilable to answer questions of the data just measured will be sui tably this ki nd . ignored if it could be contaminated . The aforement ioned measurement cycle requires The results of this analysis were used to only about 8 millise conds , allowing about conf irm that coverage of the Wash ington , 125 channels to be measured in a se cond . DC , area could be effectively achieved At the end of an ho ur , the accumulated from a sing le wel l-chosen measurement statistics will be written to magnetic site . Previous measurements had be en tape and the process will cont inue . This made from three sites to assure rel iable allows as many as 10 million measurements coverage of the area . This anal ys is is to be made on the channels in a band in now be ing performed on al l ge neral one day , wh ich makes it feasible to me asurement sites , allowing selection the measure channel usage in a statis tical ly mos t ef ficient measureme nt location . sign ificant manner. Several la rge-scale , comput er-controlled In the pa st year , the RSMS was used to receiving system de velopments have evol make measurements in De troi t, MI ; ved from the RSMS expe rience . The Air Buffalo, NY ; Mal one , NY ; and Bos to n , MA. Force Mu ltiple Re ceiver Sys tem (AN/MSR The me asureme nts mad e in the firs t three Tl ) is one such sy stem , developed for the cities were made pa rtly to le arn how the Air Force Sys tems Comma nd . The pr oj ect Canad ian al loca tion policies (different involves the de velopment, acquisition , from those of the U.S. ) affect band usage integration , and test ing of a firs t in the border areas . The Bos ton measure article preproduction multiple receive r ments included measurements on a number system , de signated the AN /MS R-Tl. The of the interesting radars in the Bos to n sys tem is being acqui red to meet the area . el ectronic warfare (EW) tr aining and testing requi rements of the Air Force . The report on usage in the Washington , The purpose of the AN/MS R-Tl is to DC , area was finished in FY 79, although prov ide measurements fo r evalua t ing the the measurements were finished near the op erational performance of ground-ba sed end of FY 78. In an ef fort to make it threat radar sys tems and the respons e of easier to in terpret the sign ificance of au tomatic and ma nual airborne el ectronic the measurements as wel l as to di scover countermeasure (ECM ) sy stems . more efficient me asurement strategies , add itional analys is was performed to help EW tra ining exercise s are conducted at define the area of coverage from the RSMS Air Fo rce ranges eq uipped with mult iple measurement site . Freque ncy listings for threat sy stems wh ich are directed at air transmitters within 50 miles of the craf t wh ich come within op erating range . Washington , DC , site were processed to The radar threats em it simultaneou s give the med ian transmitter power antenna signals at different frequencies in the gain , and antenna height for fixed sta range of 0.5 to 18 GH z. The aircraft tions and for mobile un its in each eq uipped wi th multiple ECM em itters , freque ncy band . Propaga tion to the RSMS responds to each threat emi ssion with a measurement site was cal culated using an signal contain ing noise or complex ITS developed terrain-depe ndent propaga mod ula tion waveforms des ig ned to tion mode l along 12 radial s. In some inh ibit/degrade/deceive the target ac qui cases , it was necessary to 11 smooth 11 the sition/tracking capability of the threat results along a radial to ge t a sing le radar receiver . Due to cos t limitations , 39 ------,- - , - ,.,, ,, , ...., ,, ...... • . ' • •• • • • I I • i/ • • • I I • • i • � • • ,IJa . !t:I I i I \ I \ i I j \ i I j • I \\ i \. ! ' I! \\ ', ! ' ' • ,, j ' ', • , l • • -383000 \\ _,_,..,�� • 1------. LEGEND - _.;;.____ ..,�--.:• U. S. CAPITOL BUILDING • RSMS MEASUREMENT SITE /'/ X .. GOVERNMENT TRANSMITTER SITES ...... 0 / MILE RADIUS CIRCLE -381500 --- 25 MOBILE STATIONS, COVERAGE -- 50% ...... BASE STATIONS, COVERAGE 90% BASE STAT IONS, COVERAGE - 50% 10 20 MILES Figure 1-27 . Coverage from RSHS site in Wa shington , D.C. , 162-174 MH Z band . 40 The sys tem has been completed and satellite earth termi nal s is measured and extens ive testing is underway at the anal yzed to de termine if interfering sig Nellis AFB EW range complex near Tonopha , nals to the satel li te communication ex ist. NV . Tests are to be completed in Bas ical ly, this is ac complished by September 1979 when the sys tem wi ll be me asur ing the area near the satel lite tu rned over to range ope ra·tions for termi nal location at high se ns itivity mo nitoring EW train ing activi ties . levels . The area measured is the area from wh ich signal s may be rece ived on the A third large scale , computer�controlled ma in beam of the earth terminal antenna . ins trumentation sys tem has been under Also , the area fr om wh ic h signal s may be development for the u.s. Army Commun ic a rece ived on a side-lobe of the earth tions Electronics Eng ineering terminal antenna is measured at a lowe r Ins tallation Ag ency. The Transportable sens itivity . This is permissible be cause Automated Electromagne tic Measurement of the rejection the antenna pr ov ides to Sys tem (TAEMS ) program has been supported side lobe recep tion . Both of the se pro by a number of ITS projects in FY 79. grams record al l signal s me asured wh ich The Applica tions So f tware project are strong enough to be potential inter provides software to operate the TA EMS . ferers . Ag ain , a se t of analysis pro Programs developed can be divided into grams is ava ilable . The culmination of four ca tegories : the anal ys is occurs when the various me asured signals are processed through a 1. a general scanning program , mode l of the earth terminal receiver. This mode l de termines whethe r the signal s 2. hazards scenario prog rams , will actual ly cause interference . If interference does occur , a guard ba nd 3. satellite scenario programs , around the interference fr eq ue ncy is and calculated . 4. utility programs and The fourth category of application so ft subrout ines . ware - utilities - provides a se t of pr ograms and subroutines an ope rator may The general scanning program allows the find useful on di fferent type s of mis operators to set the eq uipment , ba sical ly sions . The prog rams prov ide stand -alone a ,l kHz to 40 GHz spectrum anal yzer, to funct ions wh ic h the ope rator may run (for the de sired me asurement pa rameters . They example , a signal di rection- finding may then make a variety of me asureme nts program) . The subroutines prov ide useful using also a variety of scan op tions . funct ions when the op erator mus t write The measured da ta are plotted on the new prog rams to cover new applications . graphics CRT . A certain amount of anal y This al lows the op erator to hand le is, such as smoothing , ba ndwidth measure unforeseen applications v1 ith a minimum ment, and center frequency me asurement, effort . is available . Th is program is des igned to be applicable to many situations and A second TAEMS proj ect requi red the by itself can give an operator a very development of a Pe rformance Ve rification complete idea of what is happening in the Test Se t. The test se t is to be used to entire radio spectrum. val 1date key performance pa rame ters and to periodically calibrate the au toma tic However, for specific applications , spe receiver sys tem . The pe rtinent key cial prog rams mus t be used . One of these pa rame ters to be verified are : 1) tu ning is the hazard s scenario . The obj ective accuracy, 2) se lectivity, 3) se ns itivity , of this scenario is to measure , record , 4) tu ning time , 5) fr eque ncy response , 6) and analyze the electromagnetic rel ative ampli tude ac curacy, and 5) environment in the vicinity of ordnance isolation of input po rts . and artillery sites . Ve ry strong signals which are potential ly hazardous to the Based on previously established ve rifi site are of prime interest. The entire cation limits, a rout ine is conf ig ured to spectrum from 10 kHz to 18 GH z is scanned indicate to the op erator of the receive r repeatedly with the results recorded on sys tem wh en any of these key parame ters magnetic tape . Spe cial programs me asure are out of specification and that some both on-s ite radars and on-site commun i so rt of corrective ma intenance needs to cations radios , as these are likely to be in itiated . present high Rf levels because of the ir prox imi ty . A se t of anal ys is programs The verification te st se t wil l be semi de termines if the environment measured au tom a ted such that some of the test does or does not cons titute a potential ins trumentation will be unde r li mi ted hazard . Va rious othe r utility and da ta computer control . Sof tw are is to be presentation programs are al so provided developed to control va rious tests and to as pa rt of the scenario prog rams . update previously stored calibration correction tables. Anothe r specific ap plication is handled by the satellite scenario prog rams •.The The TA EMS , as original ly conf igured , had environme nt around actual or potential tun ing freque ncy tracking pre- selectors 41 and a low pass filter wh ich ef fectively ity is used , the noise figure (N .F. ) of eliminated image and multiple response the system below 2 GHz will be degraded reception within the frequency rang e significantl y. Above 2 GH z, howeve r, the capability of the ARS-400 subsystem N.F. is determined by the down conve rt (500 MHz-2 GHz) . In addi tion , spurious ers , and the ad ded cable length has no responses are virtually eliminated in the impact . frequency range above 2 GHz in the down conve rter design . Howeve r, be low The 2.05 to 4.1 GH z reference signal is 500 MHz , only band pass filters were eq ualized for ca ble los ses and then ava ilable , wh ich were not adequa te to ampl ified ba ck to the need ed level in keep spurious responses generated with AI I. The 100-feet cable le ngth was the ARS-400 from becom ing trouble some . chosen because of the specifications of These spurious respons es are produced the eq ualizer and amplifier al ready used wh en excessive signal vo ltages are input in the AI ! down conve rter. A sign i ficant to the first mixer and drive it into departure from this cable length (+ 20%) nonl inear operation . Some measureme nt will jeopardize the phase lock ability of applications of the TA EMS , be low 500 MH z, the down conve rters . unavoidably will require recep tion of undesired signal s of large magn i tude The 100 MH z reference signal is ampli fied which would generate harmonics and inter in each AI ! to compe ns ate fo r cable mod ulation prod ucts within the ARS-400. losses . The ATTN. Pad is used to al low a stand ard gain amplifier to be used . ITS was tasked by the Army to de sign and integrate a Vo ltage Tuned Tracking Filter In conj unct ion with the tr ans fe rable mea to cover the frequency range from 20 MH z surement sys tem , the Applications to 500 MHz, which would largely eliminate Enhancement proj ect provided for a these spurious responses in the ARS-4 00 100-foot extendable IEEE buss interface throughout th is frequency band . Th is was wh ich was developed and is be ing used as accomplished by using six (6) varac tor the link to pe ripheral eq uipment in the tuned filters . Each filter covers ap TA EMS measureme nt sys tem . Software was prox imately 0.8 octave . The filter fre also de veloped to couple the control of quency ba nd s are as follows : this pe ripheral eq uipment to the measurement systems computer. Ve rifica l. 20 MH z to 36 MH Z tion and gr aphics so ftware was developed 2. 34 MH z to 61 MH Z to ve rify and di splay characteristics of 3. 58 MHz to 104 MH z the me asureme nt sy stem as wel l as the 4. 98 MHZ to 176 MH Z eq uipment on the IE EE buss ex tender . 5. 16 8 MH z to 302 MH Z 6. 283 MH z to 509 MH z. The TA EM S Tr aining provides Army person nel with tr ain ing on various aspects of The tune voltage for each band is a nomi the TA EMS Sys tem . This tr ain ing cons is nal +1 to +9V and is derived from the ted of three courses. The first of these ARS-400. Since the ARS-400 tune voltage was eight weeks covering computer op er is a linear 0 to +lOV for a 2.05 GH z fre ation and programming of the sys tem and quency span , analog normal izing ci rcuitry va n deployment. The se cond course , on was designed to obtain the filter tune maintenance of the down converters (a voltages . pa rt of the rece iver sys tem de s igned by ITS) , las ted two weeks . The th ird course Each filter has a 6 dB band width of less was al so two weeks and covered the than five percent of f and a 50 dB sy s tems so ftware used on the TA EMS . Al l 0 bandwidth of less than forty pe rcent . of the courses were given at Fort Filter tuning nonl inearity is within the Huachuca , Arizona , dur ing the first hal f 6 dB bandwidth . of 1979. The TA EMS system include s a to wer system In ad dition to la rg e scale ins tr umenta wh ich supports a pedestal al lowing anten tion sys tems , ITS has been ac tive ly na movement in both az imuth and elevator . pursui ng the development of smalle r, A rad io freq uency equipme nt pa ckage is lower-cos t sys tems wh ich still provide also located on the tower . The Re mo te greatly improved fiel d performance and Extens ion Proj ect prov ided eq uipme nt produce digital records of valuable necessary to al low the use of this to wer measurements that can then be subjected at locations up to 300 feet from the to a wide range of anal ys is. Such equip TAEMS vehicle . Typical de sign of the me nt finds wide ap plication in the el ectronics required is shown in the measureme nt of coverage , interference , block diagram in Figure 1-28 . propaga tion , sys tem pe rformance , and spectrum- cons uming prope rt ies of eq uip The rf /IF signal is pa ssed through AI ! me nt . One such developme nt is the with no modification since the range of Automated Field Intensity Measureme nt signals on this line is so great - 20 Hz Sys tem . The sy stem wi ll be used to make to 2 GH z. Any attempt to eq ual ize and/or ord inance and pe rs onnel hazards me asure ampl ify would involve a great deal of me nts . 'The field intensity receive rs hardware . If the full extens ion capabil- 42 R�IF RF/IF < �------� 1J7 < ___;_ _--<- TA5 J4 2-4 GH:r: ISOLATOR EQUALIZER AMPLIFIER ISOLATOR CALIF MICRO - > TA5 J ,. ACRONETICS W.J. CALIF MICRO ... B1 J6 W105 CT41 CM372 MOD 5807-7 5004-280 CT41 CM372 • • 100 MH:r: dB AT TN AMPLIFIER 100 MH:r: )o ... j3 ! � TA 5J6 .. MIDWEST W.J. ... B J5 'w tos I MICRO I CA 59 1 >W106E +28 +15V REG +15V V.,j 5 ...1 1a1 r POWER POWER JUNCTIONI BOARD � : TA5J2> : __ _ w -----.�.,."> POWER SUPPLY > B1J2 _,._ >o:;.... Wl02 , W102 E JUNCTION BOARD CONTROL TA5J3 DOWN CONVERTER :> :> B1 J3 :.,._ > '--- CONTROL W101 E ---- AZ/EL_ AZ/EL JUNCTION BOARD --- TA5J 1 _ .,,. > > AZ/EL CONTRO B1J4 : W 4 � > ,.,._> �---- I � I W4E Figure l-28. ]3lock. diagram , tower extens�'On cal;l.le d,river All . used by the system are au tomatically The system can be used for ot her ty pe s of calibrated . The operator then specifies me asurements . For ex ample , average radar frequency scan width , receiver ba ndwidth , power flux could be calcula ted from a detector , etc., to the system controller . measureme nt of the APD of a radar signal , The controller se ts the specified para el iminating some of the hand calculations meters , collects the measured da ta , used now. In ad dition to APDs , the DM-4 stores it on magnetic tape , and computes can be used to measure average crossing statistics of the collected da ta . The rates (ACRs) . The APD shows how much of system has been designed to ope rate the time a signal was ab ove a pa rticular unattended for long time pe riods level . This could be used to measure (24 hours , one week , etc.), depe nd ing pulse he ight distributions , for ex ample , upon how often data are to be collected . wh ich would be useful in ex amining EW The major contribution from this pr oj ect environments or interference in crowded is the development of applcation software radar ba nds. wh ich could be utilized by other agencies having similar ord inance hazards me asure A block diagram of the DM-4 is shown in ment req ui rements . Figure 1-30. The ba sic quantization into 31 leversTs performed by 31 high-speed The DM-4 was designed and built for the comparators . A bu ffer amplifier ap pl ies Army (CEEIA) at Ft. Huachuca to make mea the input video signal to the inverting surements of electromagnetic noise and inputs of al l 31 compa rators in parallel . other signals which can be unders tood The voltage on the non-inverting input of be st in a statistical sense . Th is each compa rator is developed from a instrument (Figure 1-29 ) will ope rate as reference divider ch ain, wh ich determines part of a larger sys tem, processing an the exact voltage po int at wh ich each analog signal and sending the statistical comparator senses the level of the video measurements to a data-processing sub signal . Since the voltage at the end sys tem for further analys is or record ing . points of the reference divider ch ain is To facili tate integration into the res t se t by two digital-to-anal og converters of the system, the DM- 4 has been built (DAC's), the DM- 4 will sense signal with a full IEEE-488 bus interface , and le ve ls spaced evenly between the DA C the input signal can be anywhere within output voltages . Whenever the video the 0 to 1 volt or 0 to -lv range . The signal exceed s the reference level of a DM- 4 measures the amplitude probability given comparator, sampling clock pulses distribution (APD ) of the signal at 31 are gated into a counter associated with levels , with sampling rates up to 20 each comparator . At the end of a million samples pe r second . Al though the sampling period , the number of counts at 31 levels must be equally spaced in a given level are compa red to the to tal voltage , the highest and lowest levels nu mber of sampling clock pulses to ge t can be se t anywhe re within 0 to 999 mv . the pe rcentage of time that the input Since the sys tems with wh ich the DM- 4 signal ex ceeded each of the 31 levels . will be used supply a logarithmical ly weighted signal (the output from a Seve ral auxilli ary fun ct ions have be en typical spectrum analyzer or field incorpoi::'ated into the DM-4 to make it intens ity me ter ), the eq ually spaced eas ier for the op erator to assure that vo ltage increments of the DM-4 will data is being me asured prope rly. A actually refer to eq ual dB spacings at counter and DAC provide a 1000-step ramp the measurement system input . Th is means funct ion (0-999 mV ), wh ich is used to that the DM-4 can be set for the maximum au tomatically calibrate each of the 31 dynamic range wh ich the res t of the compa rator le vels . A small speaker sys tem can handle , or it can be se t to al lows the op erator to au ral ly monitor measure over a smaller dynamic range with the measured signal and a meter reading finer resolution . shows the number of comparator le vels currently being exceed ed (on a peak or The DM-4 is currently be ing integrated ave rage ba sis). A high-speed blanking into the TA EMS system and into a portable input and an ex ternal clock input (to measureme nt sys tem using a desktop al low sampling at time s determined by an calculator . The immed iate use of the ex ternal event) are al so available . DM-4 will be to allow these systems to make electromagnetic noise measurements Since the DM- 4 uses a log video inp ut , from thunders torms , various type s of ava ilable from all of the more common mach inery, etc . Associated computer modern field intensity me ters and spec prog rams will use the measured APDs to trum anal yzers , and interfaces to an calculate some of the more tr ad itional analys is/control sys tem vi a the IE EE-4 88 noise pa rame ters like F (ave rage noise buss, it is antic ipa ted that this ins tru a power ), V ( ratio be tw een rms and ave rage me nt will find uses in many type s of d voltage ), and L ( ratio be tween rms and me asurement sys tems where statistical average logaritgm) . Software will also da ta is necessary to ad equa tely describe be supplied to di rectly calculate the pre the measured da ta . dieted sys tem pe rformance (for some of the simple r ty pe s of sys tems ) ba sed on Two proj ects fo r the u.s. Army Combat the measured APD and an assumed signal De velopme nt and Ev aluation Command , 44 • 0 CALIBRATION PAUSE ""' 0 COUNT REACHED l.11 • I TALl< LISTEN • !! SRQ 0 i • I LLO DM-4 AMPLITUDE PROBABILITY DISTRIBUTIONS N.T.IA/I.T.S.- BOULDEB.COLO. Fig�re l-29. Front p�nel of PM-4 . EXTERNAL CLOCK ,- ---SAMPLING RATE BLANKING I �-- - MAXIMUM CO(;NT r-"L-...... -..1. --PAUSE SAMP LING MAXIMUM MAX DAC VOLTAGE 0-999 mV ·- CONT INUE 12-DECADE COUNTER l9 z 12-DECADE CALIBRATION H COUNTER � E-< t BUFFER'l 0 to 1v � • I ril � 0 TOTAL OF 31 IDENTICAL INPUT H _re COMPARATORS , GATING , SIGNAL� ... � COUNTERS , ETC . 0 to 1v 12-DECADE COUNTER INS TRUMENT DATA AND AUD IO & �1 ETER CONTROL MINIMUM MIN DAC (CARD 12 ------CONNECTIONS VOLTAGE 0-999 mV IEEE SBC 80/20 t ZT-80 488 INTERFACE BUS CONTROLL Figure 1-30. Block diagram of DM-4 . 46 Spectrum Mon itoring Unit and Freque ncy Spectrum consumpt ion is somewhat of a Extens 1on of Spectrum-MOnitoring misnomer since spe ctrum de pe nd ent tele C apability-, -are designed around two commun ications is a non-deple ting use of spectrum analyzers that operate from the resource . Even so , the pr ocess of 100 Hz to 18 GH z. The spectrum analyzers us ing the spe ctrum eithe r as a se nd er or are comp leme nted with se lections of fil a receiver (and from the broad perspec ters and pre amplifiers to increase se ns i tive, bot h must be cons ide red together ) tivity and selectivity, and with antennas "cons umes " spectrum by denying its use to to prov ide direction finding as wel l as others fo r the duration of ope rations . omnidirectional receiving capabilities from 30 MHz to 18 GH z. The rf sw itching In this se ct ion we discuss a se ries of be tween antennas , filters , preamplifiers , pr oj ects whose pr incipal object ives are and appropriate spectrum analyzers , now to be tter de fine the se spe ctrum manual, will allow easy conve rs ion to cons uming properties . au tomatic control . The antenna complement includes a loop , cavity -backed We have been particularly interested in spirals, a fixed-freq ue ncy micros tr ip the spe ctrum-cons uming ch aracteristics of antenna for direction-finding appli television receiving sys tems wh ich have cations , and a wh ip and conical monopole been ad dressed in three projects : antennas for omn id irectional signal monitoring applications . Al l receiving Spectrum-Cons uming Properties of TV equipments are housed in an 8 foot x Antennas , Measureme nt and Anal ys is of 12 foot mobile enclosure which also has a Indoor TV Antennas , and TV Antenna Sys tem he ater/air cond itioner for temperatu re Performance . The gain and pattern as a control and mo tor generators to prov ide funct1on of fr equency were measured for primary power . Location of the many 19 di fferent home television receiving antennas on the roof of such a small antennas wh ich varied in cos t from $1 .00 shelter has presented several challeng ing to $78.00. These antennas included 13 problems . Capabilities for commun ication antennas designed for · ou tdoor erection with outside locations al so are prov ided and 6 indoor antennas . Four of the ou t through two tr ansceivers , one of wh ich door antennas were designed onl y fo r VHF operates in the 30 - 76 MHz band and a reception , five were designed only fo r second wh ich operates at 141 MH z. UHF reception , and four were designed for both VHF and UHF reception . One of the The Mic roproce ssor Sys tem Upgrade proj ect indoor antennas was designed onl y fo r VHF has improved the Army 's Automatic Digital reception , four were desig ned onl y fo r Re cord ing of Electromagnetic Spe ctrum UHF reception , and one was designed to (ADRES) sy stems to permit the use of rece ive both VHF and UHF signals. industry-compa tible digital record ers , IEEE-488 standard ins trumentation inter In ad di tion to the antenna performaJtce face , faster processors , and commercial ch aracteristics wh ic h were measured , los s interfacing to the analog sys tems . In ve rsus freq ue ncy characteristics al so ad dition , the sys tems have be en designed were measured for a se lection of baluns to withstand rough hand ling and vibration (trans formers ) designed to match 75-ohm in transport . The programming lang uage unbalanced transmission li nes to 300-ohm of BASIC was added to the system to al low balanced transmission li nes and signal some field mod ifications of so ftware for splitters (devices used when both VHF and those applications that may require th is UHF signals are coupled from the antenna feature . Figure l-31 shows a field unit to the 'l.V rece iver using a common tr ans attached to a spectrum analyzer for mission line). Attenuation versus fr e record ing of spectrum data . The top unit quency characteristics fo r commonly used is a 9-track 800 bpi digital tape record transmission lines al so were ex trac ted er in a rugged case . The lower unit from manufacturer' s data . ho uses the microprocessor system with al l of the control and interface cards . A summary of our measurements is pr e sented in Table 1-3 . Cons idering the ch arac teristics of these seve ral discrete SECTION 1.4. DETERMINATION OF SPECTRUM components of an antenna sy stem , we have CONSUMING PROPERTIES hypothesized performance fo r home TV receiving antenna sy stems . Figure 1-3 2 shows expected received power , normal 1zed A major ba rrier to ef fective planning for to power received by a half-wave dipole ef ficient spectrum use is a lack of know antenna , for four ty pical type s of home ledge of the extent to wh ich the elec antenna �ystems, wh en the powe r de ns ity tronic eq uipment consumes spe ctrum beyond is 1 W/ m at the antenna . De tails fo r that needed to di rectly pe rform its ap plying this informa tion to real-world intended funct ion . Wh ile the most situations are pr esented in the pr oj ect obvious categories of spectrum-consuming final report ("Television Re ce iving equipment are antennas , transmitters , and Antenna Sys tern Compo nent Measurements, " rece ivers , a wide range of othe r el ec by R.G. FitzGerrell, R.D. Je nnings, and tronic eq uipme nt exhibits some spe ctrum J.R. Ju ros hek, NTIA Report 79-2 2, Ju ne consum ing properties . 1979). 47 ._ ""' .... . CXl :a=--= AMC 660 . .c =-:;J. Figure 1-31. Photo9raph. of one o;f; the upgrad,ed, ;f;ield, �y�tem� �itb. SJ?e.ctru:m anal�zex. Table 1-3 � Summary of Mea,surement Res_u!ts. a,nd xtra,cE. te.d Da,ta, for H.o me TV Receiving Antenna System Components- Nurrber Nurrber of Minimum Maximum Component/Paramete r 'Iested Frequencies Absolute Av erage Absolute Av erage VHF Indoor Antenna. Gain, dB 2 4 - 6. 0 - 5. 8 - 2.3 - 2.4 VHF Outdoor Antenna Gain, dB 8 4 - 6. 3 - 3.1 10.4 8. 1 UHF Indoor Antenna Gain, dB 5 10 -10 .6 - 5. 2 8.5 3.9 lliF Outdoor Antenna Gain, dB 9 3 for 8 - Ants. - 3.2 - 3.5 10.4 8. 3 10 for 1 Ant . ""' \,!) VHF Balun Loss, dB 13 4 0.1 0. 2 3.0 1.5 UHF Balun loss 13 3 0.4 1.0 7. 3 3.6 VHF Signal Spli tter Loss, dB 5 4 o. o 1.6 5. 6 3.8 lliF Signal Splitter Loss, dB 5 3 0. 2 0.6 4. 2 4. 0 Transmission Line At tenuatton Bounds vs . Frequency, dB. 100 MHZ 500 M:Iz 90 0 M:Iz 30D-ohm "Twin-Lead" 1.0, 3.6 3. 0, 8.4 4. 3, 11.5 75-ohm RG-6 Type Coax 2.0, 2.8 5. o, 7 0 3 6. 7, 10.5 75-ohm RG-5 9 Type Coax 2.5, 3. 7 6. 1, 9.7 8. 4, 13.9 1000 ,------,------.------r---.-----.------.....-----.------, D High UHF c Mid UHF Low UHF Antenna Constant { HighVHF N I � >- (..) c Q) ::J 0" � { LL Low VHF Indoor VHF or UHF Outdoor VHF or UHF Outdoor VHF- UHF Outdoor VHF-UHF Antenna Antenna Antenna Antenna A B. c. D 10 5 -45 -40 -30 -20 -10 0 10 20 2 Prec (dBW) for Power Flow of 1 W/ m2 at Antenna 'Figure 1-32 . Expected received power , normalized to power received by a half-wave length dipole antenna , for four typical types of home TV rece1v1ng antenna systems when the power flow is 1 W/m at the antenna . 50 Actual measurements will be made late in the respons e on the IF AGC with the FY 79 at 50 homes generally located in a rf AGC and AFT disabled . corridor from Chicago to Peoria . Figure 1-33 shows a map of the area with In Figure 1-36, photographs of the arcs drawn: to define sectors along the signals inp ut to the TV receiver and at corridor . We hope to obtain measurements the output of the se cond de tector are at seven or eight homes in the east shown . In the top photograph , a little sector . These measurements will over two lines of the ba seband signal are demons trate actual performance of typical shown . The top tr ace is the signal home TV receiving antenna systems and be fore the receiver, and the bot tom trace prov ide some compa rison of VHF and UHF is the signal at the output of the se cond service . de tector . The interference can be se en as amplitude mod ulation on top of the As part of a program to make more effi desired modulation . The middle pho to cient use of the broadcast spectrum so graph shows the signals going into the that additional UHF TV channels can be receiver in the freq ue ncy domain . The assigned , the Evaluation of UH F TV large amplitude signal on the left is the Receivers project has developed a 50 kHz modulated interferer at the lowe r statistical model of the TV receiver ad jacent ch a nnel frequency. Final ly, the ba sed on measured da ta . In ad di tion, bottom pho tograph shows the picture as measureme nts of TV pe rformance were made seen on the receive r itself wh ere the in an attempt to develop a more quanti interference is visible as ho rizontal tative measure of pe rformance and be gin a lines ac ros s the picture . data base of pe rformance for current receiver models. Satellite earth te rminal s highlight the spect rum-cons uming properties of antennas Currently, the assignment of a TV channel because of the ir need to coord inate to an area is based upon a fixeo ch a nnel spectrum use with point-to-point mic ro spacing de te rmined some years ago by the wave systems wh ich ope rate in the same FCC . These assignments have a number of frequency bands, bot h in the U.s. and res tr ictions on the ir use due to poten abroad . Such coordination requires a tial interference to existing channels. knowledge of antenna performance at al l The determination of what cons tituted ang les of radiation in the uppe r hemi interference and the result ing minimum sphere . A se ries of me asurements of distance spacing to prec l ude that these ch aracteristics has been made fo r interfere nce resulted in a table of the u.s. Army using a newly developed minimum distance spa cings for specified automa ted antenna pe rformance meas ureme nt channel combinations that has been ca lled system . In the La rg e Earth Te rm inal - the UHF taboos . Antenna Measuremenrs proJ ect th 1s sy s tem has been upgraded and will be used to The receiver model functional blocks are measure the spectrum-cons uming shown in Figure 1-34. The model de ter ch arac teristics (thr ee-dimens ional mines if a pair of desired and undesired antenna pa tte rns ) of three large earth ch annels is one of the taboo combination te rm inal antennas being de veloped by the If it is , the model then determines the u.s. Army Satelli te Commun ic ations Agency expected percentage of TV receivers that for use with the Defense Satel li te will be affected by any specified input Commun ic ations Sys tem . These antennas signal-to-noise ratio . If none of the are (1) the Medium Te rminal An tenna, a taboos ap ply, then the model de termines 38-foot (11.6m)-diameter , parabolic the expected level of pe rformance ba sed antenna with G/ T-3 4; and (2) a44-foot on TA SO grading . (13.4m)-diame ter , parabolic antenna with G/T-7 8. No measureme nts have be en done The measurements have concentrated on the because the antennas have not been rf portions of the receive r and on ava ilable , and it was necessary to ex tend me thods that can be easily implemented so our capability fo r making these ty pe s of that a large number of receivers could be me asureme nts due to the much greater efficiently me asured . Nume rous ranges required be tween the so urce of difficulties in making these type s of test site illumination and the test me asurements were encountered , such as antenna when testing these very high gain lack of easily accessible test po ints on antennas . (Our measureme nt techn ique and the receiver ch assis , and different ba sic capability are described in the impedances and test connectors on 1977 Annual Report .) A significant different receiver models . Some of these capability extens ion has been real ized problems and recommended solutions have throu gh the purchase of an au toma tic , been filed in respons e to FCC Notices of op tical tracking sys tem , shown in Inquiries . Figure 1-37. This sy stem will al low us to track small aircraf t at a range of The measurement of selectivity on one of five miles (8 km ). Measurements on the the test receivers is shown in G/T-3 4 Medium Terminal An tenna are Figure �· The measurements were made expe cted to be gin in January 19 80 . by stepping a cw signal through the passband of the receiver and me asuring 51 40 Ul tv 80 100 Figure 1-33. Hap of the Chicago-Peoria area where th.e nome 'J,'V receiving antenna, sy-stem measurements w�ll be made. INPUT DATA I TABOOS YES WHICH INVOLVED? TABOO? II 1 + ' CALCULATEI CALCULATE CALCULATE CALCULATE• CALCULATE CALCULATE ADJACENT PICTURE SOUND INTERMOD- CROSS- I.F. BEAT CHANNEL S/I IMAGE S/I IMAGE S/ I ULATION S/I !MODULATION S/ S/I PERFORMANCE PERFORMANCE PERFORMANCE PERFORMANCE [PERFORMANCE PERFORMANCE U1 w NO CALCULATE S/I PERFORMANCE RETURN TO CALLING PROGRAM Figure 1-34 . Conceptual dia�ram of �V performance model . CENTER FREQUENCY tMHZl 533.00 .ao -lOJlD � ��_.--���--4-��--4-��_.--��_.--�� -uo � -&00 -:a.oo1.00 - .ao Figure 1-35. Selectivity of a TV receiver as measured at the second detector output . 54 Baseband Time Re ce iver Domain Output Frequency Domain Receiver Picture f.i_g_ure 1-36 . Photographs of TV performance measurements. 55 Figure 1-37 . The automatic, optical tracking system . The elevation axis over azimuth axis, continuous rotation pedestal with zoom lens optical subsystem is on the top . The rack of control and display equipment is on the bottom. 56 The ability of receivers to perform in end di stortion by the receiver the presence of interference is a funda stage ; mental characteristic affecting cons ump tion of the rad io spectrum. In the 3. explicit, manageable , ge neral Interference Effects of LMR Re ceivers results fo r the ins tantaneous project , the performance of an FM land envelope (e) arrl frequency (8 ) mobile receiver was examined in a multi of the receive r output are ple , land-mobile interference environ obtained wh ich permit direct me nt . Measurements were made showing the calculations of both effects of mult iple interfering FM ins tantaneous arrl (time ) signal s as a funct ion of mo dulation average value.s. index , signal-to-interference ratio , signal-to-noise ratio , and frequency This anal ys is has pr ovided , for example , offse t between the victim and interferer . anal yt ic al techniques to describe the The conclusions of the study are that, ef fect of inte rference fr om a number of above threshold, the performance with FM transmitters on a single , like multiple interferers is nearly identical receiver. to the performance with a single interferer . However, significant Computations are currently underway to differences do exist in the "below de termine the effects of one arrl multiple threshold" performance . co-channel interferers , and va rious cases of ad jacent channel interferers on the Examples of the results of the study are desired received ba seband ou tput signal . shown in Figures 1-38 and 1-39. The first of these figures shows the measure ment of receiver SINAD in a single FM interference environment , wh ile the second figure shows measurement results in an interference environment composed of 3 equal ampli tude FM interfere rs . The quantity S/I in these figures is the I N ratio of signal power to to tal inter ference power at the input to the receiver, wh ile 8 denotes the pe ak frequency deviation of al l FM signals. The results of this study are described in a report entitled "Meas ureme nt of an FM Receiver in FM Interference" (to be published ) • The Theoretical FM Pe rformance in Interference pro]ect has prov1ded trac t able general results pe rtaining to the interference problem in a general , for non- ideal , FM receiver . In handling such non-l inear problems, it is found that a fully general approach is, surprisingly, much easier and analyt ical ly simpler than attempt ing to analyze "simple special cases (e.g., the standard harmonic analys is techniques)." Subsequent reduction to special cases of interest is made at once , without potential loss of key model structure or use of implicit assumptions . It is al so rather surpris ing to see how far the analys is can be carried in tractable form before approx imations , and possibly simulation of some of the analytic forms, must be resorted to . The results are new in the fol lowing respects: 1. non-ideal discriminators are included ; 2. general interference is specifical l y structured , including comb ined AM and ang le-mod ulation , with front- 57 .,...... o / g.. / / / / 0 1kHz / 0�8 = I /0 I / - / ...... --- - 5 kHz I �r I _...... _r-1 -- 3 kHz SI I 1 N , dB Figure 1-38. Measured performance of an FM receiver with a single FM interferer. 58 30 --x- - - x- - -x- - - x- --x--- - -:::o----·�---n x /.. o- ,...... 0 ,..... / / ...... :: a::J "'0 / ..._._8 = 1 kHz / 0 20 / 0 / 1 ,..A-- 5kHz I S / I1 N , dB Figure 1-39. Measured performance of an FM receiver with three equal amplitude interferers. 59 I I I CHAPTER 2. SYSTEMS ENGINEERING of the growth of distributed computing , AND EVALUAT ION and a rapid proliferation of new sources of supply for these services, as a result The obj ective of this program subelement of the FCC 's various pro-competitive is to provide telecommunication system regulatory decisions . In 1970 , the total oriented studies that include system market for data communication services and requirements, definition, cost trade-offs, equipment was $600 million . Today 's design and evaluation, or acceptance market is over ten time s as large - $8.7 criteria. These studies are user oriented billion - and market growth in excess of where the user is a Federal mission agency 20% per year is expected through the mid- or a public service user . Consulting 1980 's. services to meet these user requirements take the form of analyses, measurements , These industry changes have substantially and performance evaluations with the increased the complexity--and the impor results generally published in NTIA re tance--of the commun ications management ports or, when applicable , in technical function . The communications manager journals. The resultant performance essentially operates as a broker, or criteria and measurement methods are used middle-man , between a user requiring by Federal agencies in planning , designing , communication service and supplier who specifying , procuring , leasing , and oper provides such services. Typically, the ating telecommunication systems . user knows his application we l l, but has little technical knowledge of communica In July of this fiscal year , a new Divi tions ; conversely, the supplier knows sion was formed as described in the pref communications well , but knows relatively ace to the report. Those projects which little about particular user applications. were transferred to Division 4 during the The commun ications manager 's task is to last quarter of the year are grouped bridge the gap between these two parties, together as indicated in Section 2.1 below to optimally match offered systems and and include Section 2.2 on Satellite services with end user heeds. Communications . These projects will be reported under a new program heading next An obvious requirement for effective fiscal year . communications management is a "common language " for relating the performance Section 2.1 addresses those projects which needs of a particular user with the relate to communication systems and com performance provided by a particular munication services engineering ; Section system or service . NTIA 's Data Communi 2.2 presents those projects oriented cations project has been undertaken to toward satellite communications , Section meet that need through the development of 2.3 summarizes the terrestrial radio user-oriented , system-independent perform system performance and monitoring studies; ance parameters and measurement methods . Section 2.4 deals with radio channel Specific project obj ectives are to develop simulation and radio system performance three 2elated Federal Telecommunication standards; and Section 2.5 presents re Standards: lated work in fiber optic communications . 1. Federal Standard 1033 -- defines SECTION 2.1. COMMUNICATION SYSTEMS standard , un iversally applicable, AND SERVICES ENGINEERING user-oriented parameters for speci fying data communication system Some of the systems technology projects performance . relate to established or planned communi cation services. The services are either 2. Federal Standard "10 33A" -- will offered or leased by mission agencies , and define standard measurement methods the engineering described here relates to to be used in conjunction with the the evaluation , performance criteria, or standard parameters in assessing new technology required for efficient , delivered performance . cost-effective procurement, offering , or establishing these services . The projects 3. Federal Standard "10338" -- will described are : Data Commun ications , Non define standard performance classes Speech Telecommunication Services, Project and requirements for interconnection Green Thumb , Technical Concept Papers , of dissimilar networks . U.S. Forest Service Study , Aircraft Obstruction of Short Microwave Links , The Data Communications project is being Rural Telecommunications , EMS Communi conducted under the auspices of the cations , International Data Communica Federal Telecommun ication Standards tions , and MARAD Assistance . Committee (FTSC) . This committee is responsible , under the guidance of the Data Communications . The past decade has General Services Administration (GSA) , the produced two fundamental changes in the Office of Science and Technology Policy data communications industry : an enormous (OSTP) , and the National Communications increase in the demand for high-quality System (NCS) , for the development , coorQi data communication services, as a result nation , and approval of Federal Telecom mun ication Standards. Proposed standards 61 approved by the committee are promulgated 1. Access Time - Average value of by GSA , and ultimately become mandatory elapsed time between the start of an for use by all Federal agencies in the access attempt and successful access . procurement of telecommun ication systems Elapsed time values are calculated and services. only in access attempts that result in successful access. Figu re 2-1 summarizes the overall approach used in developing performance parameters 2. Incorrect Access Probability - Ratio for Federal Standard 1033 . The parameter of total access attempts that result development process consisted of four in Incorrect Access (i.e. , connection ma jor steps : to an unintended destination) to total access attempts counted during 1. Model Developme nt . Existing and a parameter measurement . proposed data communication services were surveyed and certain universal 3. Access Denial Probability - Ratio of performance characteristics shared by total access attempts that result in all were identified . The se character access denial (i. e. , system blocking ) istics were consolidated in a simple , to total access attempts counted user-oriented model which provided a during a parameter measurement . system-independent basis for the performance parameter definitions . A key aspect of the FED STD 1033 parameter definitions is their expression in mathe 2. Function Definition . Five primary matical form. This approach eliminates communication functions were selected the ambiguity associated with traditional and defined in terms of model refer narrative definitions and ensures that the ence events. These functions (access, parameters will be applied in a consistent bit transfer, block transfer , message way in all situations . transfer , and disengagement) provided a specific focus for the parameter The same general approach used in the development effort . access case was followed in selecting and defining performance parameters for the 3. Failure Analysis. Each primary user information transfer and disengagement function was analyzed to determine functions. A separate probability param the possible outcomes an individual eter was defined to express the likelihood "trial performance" might encounter . of each possible failure outcome , and the Possible outcomes were grouped into successful performance outcomes were three general outcome categories : expressed in terms of waiting times and successful performance , incorrect (in the case of bit and block transfer) performance , and nonperformance. time rates . Bit and block transfer rate These categories correspond to the efficiencies were also defined , to express three general performance concerns system performance from the standpoint of (or "criteria" ) most frequently resource utilization . expressed by end users : efficiency , accuracy , and reliability . A major milestone in the Data Communica tions project was achieved in FY 79 with 4. Parameter Selection . Each primary the FTSC 's decision to approve publication function was considered relative to of FS 1033 as an interim Federal Standard . each performance criterion in matrix It is anticipated that the standard will fashion , and one or more specific be available from GSA in the final pub parameters were selected to represent lished form early in FY 80. performance relative to each function/ criterion pair . Parameters were Initial promulgation of FS 1033 on an selected on the basis of expressed interim (optional) basis is intended to user interest and consisted of proba accomplish two objectives: bilities, waiting times, time rates , and rate efficiencies . The matrix 1. Allow Federal agencies maximum approach ensured that no significant flexibility in selecting initial aspect of communication performance applications . would be overlooked in the parameter selection process . 2. Improve the Standard by means of feedback from such trial applica Figure 2-2 illustrates the standard tions . parameters ultimately selected to repre sent access performance . Three specific ITS recently began work on a project which parameters were chosen , one associated will apply FS 1033 in the specification of with each of the three general performance performance requirements for a major criteria noted earlier : efficiency , Federal network , the future digital accuracy, and reliability . The selected Defense Communications System (DCS II) . parameters are : This pilot project, which is being con ducted for the Defense Commun ications Engineering Center (DCEC ) , is described elsewhere in this report . 62 DATA END USER END USER COMMUNICATION (Source) (Destination) MODELf INTERFACE SYSTEM INTERFACE DEVELOPMENT SIGNALS SIGNALS I (Reference Events) \ START TYPICAL FUNCTION END FUNCTION DEFINITION PERFORMANCE TRIAL POSSIBLE DISCRETE OUTCOMES FAILURE ,------=---, .------=----, ANALYSIS SUCCESSFUL INCORRECT NON PERFORMANCE/ PERFORMANCE �PERFORMANCE (Efficiency) {Accuracy) (Reliability) PERFORMANCE1 CRITERION FUNCTION ACCESS PARAMETER SELECTION BIT TRANSFER BLOCK TRANSFER MESSAGE TRANSFER DISENGAGEMENT Figure 2-l. Federal Standard 1033 parameter development approach . 63 ACCESS TIME W(aJ SUCCESSFUL ACCESS (aJ ACCESS FAILURE USER BLOCKING (a1) INCORRECT ACCESS (aml (EXCLUDED FROM SYSTEM INCORRECT ACCESS PERFORMANCE MEASUREMENT) PROBABILITY P(a�) ACCESS DENIAL (a 1) ACCESS DENIAL PROBABILITY P(a,) ACCESS PARAMETERS DEFINITIONS A = Total number of Successful Access outcomes counted during an access 1. Access Time = W(a5) = w(Bs) parameter measurement. s as=1 � I = To tal number of Incorrect Access 2. Incorrect Access Probability = P(a m) = Am/ A' outcomes counted during an access parameter measurement. 3. Access Denial Probability = P(a1) = A1/A' = Total number of Access Denials counted during an access para meter measurement. A' = To tal number of access attempts counted during an access parameter measurement: As+ AnftA; . w(as) = Value of access time measured on a particular successful access attempt. Figure 2-2 . Selected access parameters . 64 Another FY 79 happening of significance to systems , however , are being designed for the Data Communications project was the business terminal display and will provide decision of the American National Stan increased information bandwidth compatible dards Institute (ANSI Task Group X3S35) to with medium and high resolution CRTs. develop an industry performance standard None of the presently offered services based on FS 1033. This ANSI project will make use of audio to augment the v.ideo improve the standard by bringing addi presentations ; hence , the term "non-speech tional industry expertise to bear on the telecommunications ." This does not, performance specification problem , and however , preclude the valuable addition of will promote industry understanding and voice transmission at a later stage in the acceptance of the user-oriented approach. implementation of such services. It is anticipated that the resulting standard will ultimately be adopted by the Based on an extensive survey of available FTSC as a mandatory Federal Standard . literature , an NTIA report is being pre pared to describe , in summary , various Current ITS efforts on the Data Communica proposed and operational systems in the tions project are being focused in two United Kingdom, We stern Europe , Japan , areas : Canada , and the United States . Compari sons are offered in terms of system per 1. Support of the ANSI review/develop formance and capabilities, formats, ment effort . costs , applications , and user-oriented criteria . Also discussed in the report 2. Development of standard data reduc are possible barriers to broad · implemen tion software for FS "1033A" . tation, as the r·esult of the lack of . standards and protocols, and various It is anticipated that a final output of issues concerning policy , economics, and the Task Group S3S35 effort will be ready privacy . for formal ANSI coordination by �bout the middle of FY 80, and that an initial draft The report also addresses the potential of FS "1033A" will be completed by the end impact of interactive VIDEOTEX traffic of FY 80. upon local loop telephone service . Of particular concern are the effects of The real importance of the Data Communica widespread use of these interactive tions program lies in its substantial cost systems (that make use of home telephones savings potential. It is estimated that and local switching areas). The summary the Federal Government will be spending of a preliminary analysis of this problem about $2 billion annually on data communi appears later in this discussion , using cations by 1980. An independent National Project Green Thumb as a pilot case . Re search Council committee formed to advise the Institute for Telecommunication Several types of VIDEOTEX services have Sciences on program priorities has esti attracted widespread attention and discus mated that a 20% reduction in total Fed sion . Considerable recent domestic news eral data communications costs could be coverage has been devoted to explicit realized through the promulgation of an systems in terms of their potential use in efficient method of selecting the right the U.S. These include Project Green system or service for a given user need--a Thumb , GTE INSAC , Viewdata , KSL-TV's potential savings in excess of $400 Teletext , and a host of others . An early million per year by the mid-1980's. The interest has been expressed throughout Federal Standards being developed under Japan and We stern Europe , where some this project provide the essence of such a systems are now operational. Currently method . operational services provide visual display of information on the home TV Non-s eech Telecommunication Services. reciever . The British have pioneered in NTIA ITS has become involved in evaluation two of the most widely known of these of a group of new telecommun ication services: Teletext and Viewdata . Tele services known generically as broadcast text is a broadcast VIDEOTEX system that VIDEOTEX (simplex systems) and interactive makes use of TV broadcast or CATV to VIDEOTEX (duplex systems) . (It is to be de l iver information to the home from the noted that, during early evolution of central data bank . Information is carried several such services, various generic on the vertical retrace or blanking inter descriptors have appeared in the literature ; val of the video subcarrier . The receiver the CCITT has tentatively adopted the term has a conversion unit to strip this infor VIDEOTEX .) Some of these services are mation for display on the TV screen . The presently offered in other countries, and service transmits news , weather , public one or more may soon be offered to the interest items , stock market reports , and u.s. public . dozens of other topics in alphanumeric and graphic form for display on the home TV VIDEOTEX systems typically make use of the receiver . In Britain , Teletext currently home TV receiver as a display terminal for may be received by any of 20 million home information transmitted as alphanumeric/ receivers provided that they are equipped test or graphic/pictorial material. Some with a decoder box and have been modified 65 to receive , capture , and display the The U.S. Department of Agriculture Exten information transmitted as a portion of sion , with the support and assistance of the television subcarrier . To date only a the National Weather Service (DoC/NOAA) , small handful of such TV sets are so has drawn up plans for a prototype experi equipped . ment to test the feasibility of having state extension personnel operate a com Another VIDEOTEX system which is quite puterized network for farm and weather similar in appearance to that of the information dissemination directly into Teletext system is the British viewdata the farmer 's horne from a computer data system trademarked under the tradenarne bank . Two counties in the State of Ken Prestel . The system connects the horne TV tucky were selected as test sites for receiver to a computer bank through the equipment location and demonstration . user 's telephone and the common carrier Each county is to select 100 farmers to switched network . This type system per participate in the test. The farmers will mits the user to reque st a particular file receive an electrical box with a numeric or set of information "pages" by punching keypad and the necessary cables for plug a few keys on the decoder box at the horne ging into the telephone and TV receiver . receiver. The interactive capability The electrical box is a microprocessor allows user access to a much larger data controlled encoder-decoder plus telephone base than can be handed by the one-way modern that permits the farmer to select type of general information service . several items from a "menu" of current Customer/store transactions , real estate information stored in a computer data previews , banking , legal , and broker base . After selection of the information transactions , med ical information access, and placement of a local telephone call, travel reservations , and ho sts of other the data is automatically transmitted to interactions become practical with such memory in this electrical box and the interactive data services. telephone connection broken . The infor mation , which may be alphanumerics , full An NTIA report will include an in-depth graphic , or a mixture , may be viewed one discussion of Project Green Thumb , an frame at a time on a TV set, either in interactive VIDEOTEX service planned for color or black and white . The architecture near term implementation in the u.s. for this information system includes a medium sized state-operated computer which Project Green Thumb . NTIA/ITS has been handles all the inputs and updates local asked by the Department of Agriculture to county computers as often . as four time s work with them on an Agriculture Advisory per hour . An added potential dimension Service known as Project Green Thumb . The for the test includes the po ssibility that role of NTIA/ITS is to be strictly that of several of the farmers may input user technical advisor or consultant . Partici observed data into the data bank via their pation has been based on technical exper encoder-decoder box . tise in interactive computer and telecom mun ication local loop capabilities . It In summary , the government is interested was agreed that such participation was not in : to be construed as endorsement by the National Telecommun ications and Infor 1. testing the feasibility of ma tion Administration of any particular operating a computerized system project or system . An NTIA report will for dissemination of weather, provide a technical description of the market, and other agricultural program and an assessment of such systems production and management infor with respect to capacity , performance , and mation on a day-to-day basis; potential usefulness . 2. development of a prototype soft The Green Thumb systems , when widely ware support system for the implemented , are expected to be justified test; and on the basis of helping to reduce the more than one billion dollar annual losses of 3. providing test parameter data to food and fiber , which are directly or evaluate the usefulness and indirectly attributable to adverse weather acceptability of the information conditions , crop diseases , insect invasions , and the information dissemi harvesting too early or too late , and nation system . other problems facing the U.S. farmer in his decision making processes involving A chapter of the NTIA report on Non-speech his agricultural business . Telecommunication Services , en titled "The Impact of Information Systems on Public There follows a descripton of the various Switched Networks ," presents results of an participants in Project Green Thumb , ITS analysis of potential future telephone together with goals expected to be reached traffic problems resultant from widespread sometime in 1980-81 as the Green Thumb use of interactive VIDEOTEX systems . system is implemented . Project Green Thumb parameters are used in the analysis, which addresses the possible effects of such systems usage on rural 66 local loops and local switching centers . that is suffered at each conversion . The In addition , the report shows that the paper addresses these technical concepts . number of trunks to the information data bank markedly affects the service provided . The second paper concentrates on the variety of communication gateway inter In rural areas , where lines may be no isy , faces that are encountered in the . current this traffic analysis showed that, for the military plan . In some cases , there Project Green Thumb in Kentucky , blocked appears to be only ill-defined require calls could be out of the acceptable range ments for the interfaces , and there is a when as few as 100 VIDEOTEX subscribers distinct possibility that the impact of are participants in the system . the needs of the interface are not under stood . This paper discusse s a mapping of The traffic analysis was based on the the interfaces encountered in the m.ilitary hypothetical example of 100 farmer instal communications heirarchy with a view to lations , each originating one call per assisting military planners in more fully hour , presumably at morning and evening understanding future needs and trends . hours not conflicting with field work . Holding time (elapsed time from telephone U.S. Forest Service ADP Commun ications connect to disconnect) was 2.4 minutes per Study. ITS has reviewed U.S. Forest call for a 4 kilobyte memory (8 "pages") Service Region I telecommunication require and 4.8 minutes per call for an 8 kilobyte ments for upgrading the ADP services and memory. For no isy channels, holding time enhancing the communication services at was doubled in order to permit completion the Forest Service Northern Region . The of transmission of page information . project consists of defining the operational support requirements , developing cand idate Re sults we re obtained for 7-, 14- , and 21- data system configurations , making per trunk groups connecting the local switch formance-cost trade-off analyses , recom ing center to the information data bank . mending a data-communications . system Calculat ions made using telephone traffic configuration design , ahd preparing imple engineering tables indicated the percent mentation plans reflecting time-phasing of age of blocked calls based on the numbers the procurements. of trunks terminating at the computer. Results are reproduced in Table 2-1 . Functional diagrams have been prepared from which the ADP and communications Technical Concept Papers . The u.s. Army requirements may be developed . The Commun ications Command has responsibility objective of the project is to develop and for a wide range of communication systems , document the methodology of specifying and including strategic , tactical , and non procuring such telecommunication system tactical . Many operational problems improvements. The results should be result from a mismatch in communication applicable to other agencies of the Federal requirements, formats , o� cryptography . Government . This program is addressed to a general understanding of the se problems . The Aircraft Obstruction of Short Microwave intent is to write two technical concept Links . This project was a continuation of papers which will give an overview of two an experimental program initiated in the distinct communication problem areas. It previous fiscal year . It was supported by is hoped that they will assist management the u.s. Army , CEEIA, at Fort Huachuca , in better understanding the options avail AZ . The objective was to determine the able to them . effects of aircraft penetration of a microwave transmission beam over rela The two technical concept papers will tively short links , with emphasis toward concentrate on the following : digital communication systems . The two important parameters in the measurements 1. secure voice communications , we re the power fade depths caused by the 2. communications mapping for the aircraft and the multipath that might be gateway interfaces. caused by reflections . The first of these examine s the current The experimental data were obtained from plan for military secure voice communi existing microwave links operated by the cations and the associated interface Federal Aviation Administration at the problems . There exists a variety of Atlanta/Hartsfield Airport in Atlanta , GA , interface needs due to a variety of and at O'Hare International Airport at military secure vo ice terminals and Chicago , IL . The results were summarized signal formats. This leads to a rathe r in the Annual Technical Progress Report complex interface problem which portends 1978 issued by NTIA/ITS . An NTIA Report- a high financial and temporal cost . The 79-14 entitled "Aircraft Obstruction of interfaces must handle a variety of Microwave Links " was published in January cryptographic keys and a variety of 1979 , and is available from ITS , Boulder , signal formats . Signal format conversions co . (at interfaces) are particularly trouble some in view of the voice quality degrada tion and speaker recognition impairment 67 Table 2-1. Blocking Estimates For Green Thumb Test 4 k Mem 8 k Mem Quiet Noisy Quiet Noisy Call attemp ts/hour 1 1 1 1 Holding Time 0.04h 0.08h 0.08h O.l6h Offered Load per subscriber (Erlangs) 0.04E 0.08E 0.08E 0.16E Blocking % 7 Trunks Los t Model 6% 35% 35% 65% Held Model 11% 68% 68% 98% 14 Trunks Lost <0.1% 3% 3% 25% Held <0. 1% 3.5% 3.5% 70% 21 Trunks Lost 0 0 0 5% Held 0 0 0 16% This assumes 100 subscribers make 1 call attempt per hour with ho lding time of 2.4 min/call for 4k memory (Quiet) or 4. 8 min/call for 8k memory (Quiet) and holding time doubles for noisy channel. 68 Rural Telecommunications . This project is o What time delays are incurred before a technical supporting activity for the the appropriate medical resources broader NTIA Rural Communications Program. commence advanced life support or ITS hosted a planning workshop in March some other level of emergency care? 1979. Three rural communities have been selected by NTIA for evaluation and special The obj ectives of the study were designed emphasis in determining specific rural to assist telecommun ication managers and telecommunicati6n needs . These are Haywood planners by providing analytical , simu Country , NC , Rio Arriba County, NM , and l�tion , and measurement techniques for : San Joaquin Valley, CA . Representatives o from these communities presented reports understanding the individual EMS delay components and their impact on on surveys conducted by them to determine local needs . Industry representatives the delivery system , from eight sectors ranging from telephone o adaptation of a simulation modeling services to slow- scan video and satellite technique for evaluating existing or services presented highlights from their planned EMS telecommunication systems industry which may be useful in meeting or subsystems , rural telecommunications needs . Three o working groups represent ing mobile communi collecting and evaluating time delay cations , broadband and video commun ica data on existing EMS telecommun ication tions , and telephone and data communi systems , and cations were formed with ITS representa o providing a cross reference between tives participating in these groups . specific EMS delay components and previous applicable research (lit A specific need for mobile communications erature) . to support medical services in the Rio Arriba County, NM , site was identified for For the purpose of this study , the EMS fol low-up by ITS . Field site vi�its were system was considered to be composed of made and agreements for use of the New three subsystems or processes ; namely : Mexico State EMS system were developed . Citizen Access, Dispatch and Resource , and Further developments have pursued a radio Medical . This is shown diagrammatically coverage problem in one portion of the in Figure 2-3. Detailed descriptions of country . This specific problem has led to these processes and the time events are the need for defining waiver criteria for contained in the resultant Master of the use of dedicated EMS frequencies in Science Thesis submitted to the Department rural areas . Efforts are continuing to of Electrical Engineering , University of define , in a generic way , recommendations Colorado entitled , "Simulation Modeling of for telecommunications infrastructure for Emergency Medical Services (EMS ) Telecom rural communities . The addition of tele munication Systems ,,; by H. David Hunt . commun ications into the economic develop ment plans for these communities seems to The demonstration model in this study ' be a reasonable approach to stimulating employs a dynamic , stochastic simulation appropriate developments in response to technique that accurately accounts for the the Presidential initiative in this area . passage of time during the process depicted in Figure 2_- 4. The model is capable of Emergency Medical Services (EMS ) Communi closely representing the stochastic nature cations . During FY 1978 , ITS prepared an of the EMS environment . The model was Emergency Medical Services Communications validated against analytical equations System Technical Planning Guide . After wh ich are known to represent certain extensive review by concerned Federal empirically derived results . The model agencies, the guide was published as NTIA was validated using data on Emergency SP 79-3 . It was introduced at a confer Telephone Circuit Analyses, Emergency ence , "Rural EMS Under Construction," in Operator and Dispatcher Staffing Analyses , Oklahoma City in May . Radio Dispatch and Emergency Medical Channel Analyses, and Medical Unit Traffic The primary effort during this fiscal year Analyses . The difference between prob has been directed toward a study of EMS ability measures calculated using the telecommunication subsystems to develop analytical models and the results of the techniques and examples which will aid simulation model was generally 1% or less. system managers and planners to better understand the telecommunications processes A cross-reference matrix between the model and to evaluate the performance of existing flow-chart decision points/subprocesses or planned systems . The study resulted in delay blocks and relevant bibliographic an EMS simulation model which can be references (a total of 96 different refer employed in evaluating the following ences) provides the reader a source for subproblems : the reference values used in the model. 0 What time delays are incurred in gaining access to emergency medical MARAD Assistance . Since 1973, ITS has resources? provided a range of technical services to the U.S. Maritime Administration (MARAD) , 0 What time delays are incurred in the including test facilities and assistance , dispatch of appropriate medical technical representation at national resources to the emergency scene? (RTCM) and international (CCIR) committees, 69 DISPATCH and RESOURCE SUBSYSTEM CITIZEN ACCESS MEDICAL SUBSYSTEM SUBSYSTEM EMERGENCY SCENE Figure 2-3 . EHS telecommunications subsystems OCCURANCE ARRIVAL ARRIVAL OF EMERGENCY AT SCENE AT HOSPITAL TRANSIT TIME TRANSIT _j DETECTION .. REPORTING ANSWER _,•+• - D ISPATCH -_,•�,._, _ -.. _ ___, •..., .,__..._ _ <-- TO SCENE _ •..., . AT SCENE --..• •-To HOSPITAL� 1- I I I I - _,I ,__ - I I I I I I I I I I I I I CITIZEN ACCESS __ DISPATCH and RESOURCE ______MEDICAL ___ PROCESS ---'-t----- ....,.+ PROCESS ...... ,.,.,�� 11--•--- PROCESS I I I I I I I I I I TOTAL EMS SYSTEM PROCESS TIME Figure 2-4 . Emergency system processes . 70 and advanced commun ications studies . Some NOTE : The following projects (through of the specific efforts in FY 79 are Section 2.2.) were under the new Division described in the following paragraphs . 4 for the last quarter of the fiscal year . 1) ITS provides ma jor technical input USPS Electronic Message Service System . towards the development of an Automated This project now constitutes Phase VII of VHF/UHF Mari time Mobile Telephone System the NTIA/ITS support of the Electronic through participation in RTCM Sub-Committee Me ssage Service System (EMSS) program for 71 and CCIR Interim Working Party 8/5 . the u.s. Postal Service . Again, the ITS ITS analyzed the traffic handling capacity provides technical support , analysis, and of dedicated calling channels for such a documentation in support of the EMSS system under various operational conditions program . The current agreement requires and submitted a report to the IWP . The ITS participation in the development of an system concepts evolving in the u.s. and integrated EMSS program plan , providing in Europe are somewhat different , largely assistance to the USPS in preparation of due to different geographical and political the statement of work (SOW ) for the incep aspects . In the u.s. , "trunking ",that is, tion of an EMSS , developing software time-sharing of radio channels by several analysis and computer modeling of the coast stations , is generally thought to be EMSS , and developing a dynamic me ssage essential for development of a spectrum flow simulation model of the initial EMSS . efficient system . In Europe , trunking is Other tasks require ITS to determine not generally considered acceptable due a) me ssage security requirements and complete to the great number of political bound development of trunk network planning aries , b) in certain cases the many coast factors . stations needed to cover a relat ively small area due to geographical (terrain ) The previous work of ITS has aided in the features, and , c) the requirement for development of 52 EMSS concepts which then simu ltaneous calling by these coast sta led to the selection of three and then a tions to minimize call set-up time . ITS single candidate by the USPS . EMSS services has been instrumental in the development would be phased in over a number of years of unified signaling procedures over the depending on customer demand and implemen radio channel so that compatible shipboard tation strategy to be employed , which is signaling equipment will be possible at a subject to market factors such as customer minimal cost increment . acceptance. Various computer modeling alternatives and growth strategies were 2) ITS is conducting a systems study to emp loyed by a private contractor for the evaluate the feasibility and capability of three final candidates in cooperation with an overlay spread-spectrum communication the ITS . These economic analyses aided in system in the VHF (156 to 162 MHz) band . the selection of the final candidate by A major impetus for this study is the fact varying growth strategy with services and that in the u.s. only a relatively small market ,response as variables . The services number of the channels in this band are at various phases would offer magnetic available for maritime use , in part due to tape , optical character recognition , grandfathering clauses (e. g. , use by the facsimile , and public terminals for input railroads of certain channels) . A spread applications . Output services could spectrum system could use the full band include black and wh ite printing or color . available and provide additional communi The market response strategy was based on cations capability, provided it does not 1) a slower than expected market , 2) a cause interference to the existing services market that develops as predicted , and 3) and that the interference by other users a faster than expected market . The model to the spread-spectrum system does not ing used alternatives that takes the EMSS exceed acceptable levels. more than 20 years to develop to maturity or to have the EMSS terminated when market 3) A new CCIR Interim Working Party 8/8 demand is low in as short a period as 8 was formed in May 1979 to determine the years. This would permit capital invest operational procedures and any other ment to be recovered if the EMSS fails to matters necessary for the early intro gain customer acceptance . duction of Digital Selective Calling (SELCALL ) in the Maritime Mobile ter The candidate chosen by the USPS has the restial service . ITS has for many years characteristics shown in Table 2-2 for a been a major contributor to the develop mature system which could take 20 years to ment of SELCALL and to the international implement . adoption of this system (CCIR Recommen dation 439-1, adopted at the 1978 CCIR The EMSS has the potential of operation as Plenary) . T. de Haas has been named as a envisioned in the accompanying diagram U.S. member to the new IWP 8/8 and partici (Figure 2-5) . The principle of the EMSS pates in the work of RTCM Sub-Committee 74 is as follows : the USPS would accept where mo st of the preparatory effort is physical media such as paper copy me ssages taking place . and magnetic tapes through conventional mail carrier pickup or customer delivery at designated facilities such as associate 71 Table 2-2 . Characteristics of Mature Final EMSS Candidate Annual Average Number Size Number Volume Letter of of EMSS of Public (Billions ) Size (Bits) Stations Staff Terminals 25 .0 67, 000 87 4,387 67,052 Annual Productivity Cost/1000 Total Operating Million Me ssages Investment Costs Messages ($) ($ millions ) ($ millions) pe r Person Year 19.5 1791.3 309.3 5.7 Figure 2-5. EUSS message routing . 72 post offices (APOs) or sectional center An operating format is established which facilities (SCFs) . The messages would be identifies use of message forms , labeling converted at EMSS stations for transmission of media container for magnetic tape , via leased common carrier services such as method of billing , method of media delivery satellite links to EMSS destination sta or pickup by the message originator , and tions . On message receipt at the EMSS other operating procedures . station , the messages woutd be stored in computer memory , sorted in memory , and Service implementation planning considers then printed and enveloped for carrier factors which influence station design delivery . The messages would be distrib requirements . These are the .number of uted to the customer by truck or mail me ssages , bits per message , the number of carrier as in current practice . media conversion devices to be required , and the service features. This implementa Other message entry might be by the cus tion planning helps serve as the basis of tomer at a public terminal or from company modification of software which was used offices , the former via leased lines and for the growth and economic analyses the latter via leased or customer-owned described earlier , but is now being under lines to the EMSS station . No electronic taken by ITS in more detail . Another message distribution by the USPS would section is used to develop algorithms that take place . will be used to examine relative frequency of message arrival at an EMSS station and During the past year the ITS has prepared estimated message volume for each applica an EMSS System Engineering document which tion at each station so that station and provides a planning guide to promote system requirements can be analyzed. development of the EMSS in an orderly manner . The document contains a system The service planning summary section of description, requirements , and development the document lists 22 applications with planning factors for the EMSS . . Two areas over 20 possible services considered for are covered in the document : service each of the applications . planning and system planning . The second area of the document , system The first area, service planning , involves planning , develops guidelines for the EMSS development of applications-oriented physical system, its functions , and service groups and definitions rather than operations . Planning guidelines have been technology-oriented services. There are considered for EMSS stations , trunk five applications-oriented service groups . networks , and local telecommunications . They are : Transact-mail which includes Interface planning has been considered billings , invoices, purchase orders, and within EMSS stations , among EMSS stations , payments such as money orders ; Ad-mail trunk networks , local telecommunications which includes various forms of advertis networks , public terminals, and user ing ; Express letter which would be a (customer located ) terminals . general message service among businesses, government , and household; Tele-mail Another area of support has been in includes priority forms of transactions , computer programming and data base adapta advertising , and general messages ; Custom tion . The ITS has succeeded in modifying mail which might permit unusual features a contractor-developed parametric analysis such as special ink and paper . model of the EMSS and a network costing program for operation on the Boulder The planning for these applications is Laboratories CDC 6600 computer . Signifi defined in terms of input mode , method of cant changes were made in the software to collection , output mode , method of delivery , enable successful operation . This work is and service features such as method of continuing for the current contract. payment , level of message security , and whether colored paper and ink other than Currently , completion of an integrated black is to be used . For example , a bill program plan for the EMSS is underway . to a customer may start at a company as This task requires a review of EMSS pro part of a large number of magnetically gram plans , identification of program encoded bills on a reel of tape (input areas requiring planning support , areas mode ) , collected by the USPS (collection critical to EMSS inception , and develop mode ) , black ink printed on white paper at ment of a total program plan for EMSS to the destination station using a standard maturity. level of security (service features ), and delivered by the USPS to the addressee The development of a draft document con (delivery mode) . tractor SOW of hardware/software require ments for EMSS inception is also in Service requirements for applications are progress. Service and system planning are developed in the document which serve as part of the document which requires guidelines for customer, USPS , and EMSS contractor generation of functional facility interfaces . These interfaces specifications for the initial EMSS . establish procedures to be followed at EMSS stations , public , and user terminals. 73 There are three areas of effort in soft and AUTOSEVOCOM systems during the 1980's, ware development . One is in the identi has been motivated by two fundamental fication of software by functional analysis changes in the military commun ications at and between EMSS stations that will environment : control message input/output processing , message sorting , control functions, and 1. A substantial increase in the demand bookkeeping . A second is writing software for high quality data and secure that will permit estimates of message voice commun ication services , in arrivals at stations and for the entire recognition of the pow erful "force initial EMSS . This work is then related multiplier" effect of communications . to the earlier programs which were used to determine EMSS and station costs . The 2. Dramatic improvements in the tech third is the development of a dynamic nologies of digital transmission and me ssage flow simulation model handling network resource sharing, typified by input/output flow of me ssage traffic at the development of the Digital European EMSS stat ions and through the trunk net Backbone (DEB) and the ARPANET . works whether satellite , terrestrial , or hybrid . This software will be capable of Recent Defense Department planning docu handling var iable message flow rather than ments indicate that the second-generation peak loads , and will be used to establish DCS will diff er from the current system in adequacy of equipment specified in the three major respects : EMSS . 1. The analog circuit switches and FDM Another task is underway that will review transmission facilities currently requirements for message protect ion of supporting AUTOVON will be replaced physical media and electronic data. by digital equipment. Protection of the physical media includes protection from fire , theft , and tampering 2. The traditional AUTOD IN store-and with message contents . Me s sage protection forward message switching network during network transmission may be through will be augmented and , to a growing the use of encoding based on the Data extent , replaced by AUTODIN II - a Encryption Standard (DES ) and the applica second-generation packet switching bility of proposed Federal Standards 1026 system based on the ARPANET . and 1027 which define compatibility and security requirements. Costs associated 3. The existing AUTOSEVOCOM system will with both protection areas will become be replaced , under the Secure Voice part of the EMSS data base . Improvement Program , with improved narrowband secure vo ice services Completion of work started during previous provided by the new AUTOVON facilities. agreements is expected in trunk network The number of voice subscribers development factors . Starting with 10 receiving security protection will be cities specified for EMSS inception , the significantly incre ased. trunk network will be expanded to accom modate 18-25 cities and finally a mature The planned DCS II network represents a network of close to 100 cities. This direct application of the new technologies trunk network will be based on leased of digital transmission and resource private line services. Plans are being sharing to the post-1985 needs of military made for a network topology growth which communications users . In comparison with will not hinder hierarchal network develop its predecessor system, DCS II offers the ment . Link capacity assignments will be potential, of substantially improved end made and network flow controls planned . to-end �erformance , broader geographical This trunk networking is interrelated with and organizational coverage , and more the network cost software effort described flexible adaptation to growth and change . earlier . In addition to these operational benefits , Determination of Digital Transmission the planned DCS II network offers the Technical Criteria . This project, spon potential of major cost savings. The sored by the Defense Communications superior reliability and maintainability Engineering Center in Reston , VA , was of the digital DCS will translate into initiated in June of 1979 . reduced training , operation , and mainten ance costs ; and its improved performance As the primary engineering arm of the will encourage military users to employ Defense Commun ications Agency, the Defense the common-user network in preference to Communications Engineering Center (DCEC ) inefficient , costly dedicated services . has the major responsibility for developing and implementing the second-generation While the potential benefits of DCS II are Defense Communications System (DCS II) . substantial , their realization will not This planned system , which will gradually be easy. Its designers face major problems supplant the existing AUTOVON , AUTODIN , in determining user requirements for services; in evaluat ing the performance of candidate facilities ; and , perhaps mo st 74 importantly, in relating these two varia new and complex signaling issues which bles . The success of the DCS II system arise in an integrated (voice/data) will depend to a large extent on how communications network , and (6) an evalu effectively these problems are addressed ation of switch element capacities in during the next two to three years . access area digital switching systems . The ITS will contribute to the solution of Studies 1 through 4 were reported earlier the problems noted above by developing and are described in previous annual precise technical performance criteria to reports. Studies 5 and 6 were completed be used in the specification of DCS II in 1979 and are described here . systems and subsystems . The overall project has been divided into three major NTIA Report 79-13 , "Control Signaling in phases. Each phase requires approximately a Military Switching Environment ," discus one year of effort . Figure 2-6 illustrates ses various factors including network the ultimate objective that ITS hopes to topology , traffic characteristics , switch achieve . User-oriented parameters and ing technology , and transmission media values will be developed in phase A for which affect the choice of control signal one digital and one analog service mode . ing techniques to be used in future mili In phase B technically-oriented parameters tary networks . and values will be determined for various subelement interfaces of the two systems . One of the major issues which arises in These must be related back to the user the design , development , and deployment of oriented values. Finally, in phase C the a telecommunications network is the results obtained in phases A and B will be specification of the network management applied to other service modes and other and control . The design of the control user applications . Thus , ITS ultimately signaling system for DCS access area expects to "fill in the blanks" shown on switche s is a prime example . Because the figure . military networks tend to evolve slowly , perhaps over a decad� or two , resolution This project relies heavily on the data now of the key control signaling issues communication program which is concerned could influence , if not fully determine , with developing user-oriented standards the direction networks will take in the (e .g. , FS 1033) for digital communication 1980 's and 1990 's. services. The spec ification of user oriented parameters for analog services is Emphasis is on those systems using common a crucial step in the technical criteria signaling channels. Digital signaling development process . systems having potential application on both the line and the trunk side of a Figure 2-7 illustrates the basic issues digital switch are also examined . Some of that must be addressed in conducting a the potential signaling interfaces to an systematic analysis of user communication access area digital switch are illustrated performance requirements. End-users are in Fig'u re 2-8 . depicted as processes or functions . The objec tive of the user requirements anal This report provides an introduction to ysis is de f ined as the effectiveness of these concepts and issues involved by this function and the impact the system reviewing the more important advanced has on it. signaling concepts available today . Phase A of this project is expected to be A second report entitled "Switch Elements completed in the spring of 1980. Capacities in Access Area Digital Switch ing Systems" is being reviewed by the Access Area Digital Switching System sponsor for publication as an NTIA report (AADSS). The u.s. Army 's Communications during the summer of 1979 . This report Systems Agency (CSA) at Ft . Monmouth , NJ , defines the parameters wh ich determine the is evaluating concepts and alternatives capacity of modern switching systems in for providing an effic ient interface terms of four major switch elements : the between the future Defense Communication interface , the switching matrix, the System (DCS) network and cont iguous mili control processor, and the signaling tary base environments called access elements. Existing commercial switching areas . systems are used to exemplify the charac teristics of representative switches. · ITS is conducting analyses in support of Numerical parameter values are developed this AADSS program . Previous ITS efforts for a range of switch sizes having appli have included studies on (1) parametric cation in military access areas . Tele cost alternatives for local digital dis traffic engineering concepts wh ich infl� tribution systems , (2) preliminary evalu ence switch capacity are introduced . The ation of hub alternatives , (3) an example study results are applied to a specific of the design for a digital time division military complex whose communications switch with stored program control, (4) profile is known . A digital switch con traditional signaling techniques for cept using local and remote concentration controling the switch , (5) a study of the units is used in the example . Figure 2�9 75 PHASE A PHASE B ---"A A r,---- 'r ...... __ __ ...... , USER ORIENTED TECHNICAL Parameters Values Parameters Values SE C >- >- >- >- >- >- >- ..... >- ..... t- � (.) >- u >- (.) >- ..... (.) >- z u ....J z u ....J z (.) ....J z u ....J - IJJ ....J IJJ ACCESS (.!) IJJ ACCESS o u ....J - Figure 2-6. Criteria development project overview. INPUT INPUT 1 2 USER COMMUNICATION USER t 1 t 2 INCREASED FUNCTION SYSTEM FUNCTION INCREASeD 'VALUE' 'VALUE' T • NATURE • PERFORMANCE • NATURE T • EFFECTIVENESS •COST • EFFECTIVENESS l_ OUTPUT OUTPUT j_ i 1 � 2 A. GENERAL MODEL User Communication = f { Effectiveness } l ( Performance ) Communication Communication = Performance f Cost { } 2 ( ) COST/EFF ECTIVENESS RELATIONSHIPS B. Figure 2-7. User requirements analysis concept . 77 I NOTES: SPC - STORED PROGRAM CONTROL PCM - PULSE CODE MODULATION MUX - MULTIPLEX MOD - MODEM Ana log Transm ission _ Digital Transmission Fa cilities :..__ Faci11t1es 1 Figure 2-8 . Potential signaling interfaces to access area digital switch for transitional network environment . 78 Remoted Components ------1+----- Switching Hub ______.., r--- Space Switch � DSVT TMG AVT DT DVT ,---, ��ook --�------�:1I I : �------�1 c ��� ------����---L------��� L __ J TRU Legend DSVT' Digital Secure Voice Te rminal Remote Concentration Unit AVT ' Anok>g Voice Te rminal Trunk Repeate r Unit DT ' Digital Ter minal Trunk Interface Unit DVT' Digital Voice Ter minal Time Slot lnterct' Figure 2-9 . Local and remoted components of a switching hub . 79 illustrate s the concept employed for the signal center is shown in Figure 2-11 . remote switching hubs serving as private The functional units shown in this figure automatic branch exchanges . These hubs may be spread over an area 3 km to 5 km in home on a central switching hub which diameter . Other topologies such as loop serves as the access to commercial carriers and star-loop combinations are be ing and to the DCS backbone switches; see evaluated for bus-type networks . It Figu re 2-10 . appears that the two measures of effec tiveness--deployment time and surviva One of the primary benefits of the AADSS bility--are often conflicting . The ITS is will be reduced DCS access line costs by attempting to develop methods for quanti eliminating direct homing of each military fying the survivability of potential bus installation to the backbone network . type architectures used at the command Inter-base connectivity enroute to the post level . One promising means for backbone DCS can reduce the overall providing such a quantitative measure of access circuit mileage , increase access survivability is to determine the effect circuit utilization in portions of the of inoperative nodes and links on the access network, and eliminate backbone grade of service . The results of this switch traffic for intra-area calls . On study can then be used to optimize the a current project, ITS expects to analyze topology to enhance survivability and the AAD SS for two specific military simultaneously reduce deployment time . regions and to include all of the multi service access points within each region . A report describing the results obtained The study will include an assessment of is planned for the fall of 1979 . the technical and practical feasibility as we ll as the cost effectiveness of various Telecommunications Protection. The intra-area and AADSS backbone connectivity Telecommunications Protection program was alternatives. started in fiscal year 1979 by NTIA in order to conduct the Presidential Directive Command Post/Signal Center Bus Distribu (PD/NSC-24) Executive Agent responsibili tion Concept Design Program . The semi ties in communication protection assigned tactical nature of transportable Army to the Secretary of Commerce and delegated Command Posts and Signal Centers (CP/SC) to the Administrator , NTIA . The program poses many real operational problems to is directed by the NTIA Special Projects the Army Field Commanders. This appears Office in the Office of Federal Systems particularly true for the internal CP/SC and Spectrum Management . The Special communications distribution systems . Such Projects Office in Wa shington , DC , develops a system must often be installed , modified , policy recommendations and conducts Federal or transported rapidly . The system must agency telecommunication protection sur be survivable , movable, and flexible . Its veys . The technology and technical evalu telecommunications performance must meet ation part of the program is conducted at all military operational requirements ITS in Boulder , CO . faced by transportab le CP/SC scenarios . Presidential Directive PD/NCS-24 provided ITS is taking an in-depth look at new and certain policy guidelines that included : evolving techno logies to ascertain whether and how new system concepts (such as bus 1. Government classified information type distribution) can beneficially replace relating to national defense and the existing facilities . This ITS effort foreign relations shall be trans is sponsored by the u.s. Army 's Communi mitted only by secure means . cation Electronic Equipment Installat ion Agency (CEEIA) at Ft . Huachuca , Arizona . 2. Uncl�ssified information transmitted The prime obj ective is to provide a func by and between government agencies tional design and specification of a bus and contractors that would be useful type transmission system to replace cur to an adversary should be protected . rently used wire pairs and cables used in transportable tactical command posts. 3. Nongovernmental information that During the course of this program, ITS has would be useful to an adversary shall collected a considerable amount of infor be identified and the private sector mation relating to command post signaling informed of the problem and encour centers and bus-type distribution centers. aged to take appropriate protective This has been accomplished by literature measures. search, discussions with cognizant person nel , and by visits to tactical field The organizational structure established exercises at Ft . Huachuca , AZ , and Ft. to address the PD/NCS-24 directive in Hood , TX . This information is being cludes the National Security Agency acting evaluated and will be summarized for in its traditional role relating to clas inclusion in the final report to the sified information and national security . sponsor . A major section of the report NTIA assumed a new role dealing with the deals with overall CP/SC network design . protection of unclassified , non-national The current method used for interconnec security related information . The delega tion of functional units in a typical area tion of these responsiblities is summar ized in Figure 2-12 . 80 '------.,.-- Remote Remole Central Remote Concentration Hub Concentration Hubs SwitchinQ Hubs SwifthinoHub Figure 2-10. Implementation concept for digital concentration , multiplexing , switching , and transmission in the access area . 81 ' LOCJ!.L TELEPHONE LINES ro N Figure 2-11. Interconnection of functional units for a typical area signal center . ORGANIZATIONAL STRUCTURE �,.1 o' c� ,.. .,. �+ � �.., : - - � ��., f t-� �, : $��:<4rrs of co w NATIONAL SECURITY NONNATIONAL SECURITY RELATED INFORMATION RELATED INFORMATION Figure 2-12. Delegation of responsibilities. Most aspects of the program are classified ITS also participates in the writing of including the specifics on ITS ' role and telecommunications standards concerned activities. The report given here , there with encryption. Two standards are in the fore , is by necessity broad and describes final stages of development . They are the program as a whole rather than focus Federal Standard 1026 (draft) and 1027 ing only on ITS ' technical evaluation (draft) dealing with the encryption of role . data for communications and the physical security of the encryption equipment . The The principal threat to telecommunications work is being accomplished in Subcommittee that NTIA is addressing is the vulnera Three (SC3) of the Federal Telecommuni bility of both terrestrial and satellite cations Standards Committee (FTSC) . microwave radio to eavesdropping . The types of information of concern to NTIA in SECTION 2.2. SATELLITE COMMUN ICATIONS their telecommunications protection role include : The main effort in the satellite communi cations program area during FY 1979 has o Financial Information been on a continuing direct-funded pro gram. On this program, the regulatory , o Planned changes in prime in economic, and technological aspects of the terest rates development of small-antenna earth station o Support of the dollar in foreign systems have been studied. The major exchange markets long-term goals of this program are : o Commodity Market Forecasts 1) To foster the use of new and existing telecommunications systems and ser o Supply of Critical Materials vices by public service agencies (including private groups and all o Strategies for International levels of government) to help those Negotiations agencies meet their needs and goals more efficiently and economically. o Selected High-Technology Information . 2) To help develop for public service NTIA has identified long range goals and agencies the technical means to objectives to meet the responsibilities improve the efficiency and cost delegated to NTIA by the Department of effectiveness of their communication Commerce as executive agent . In tele systems . communications protection of government derived unclassified information , the 3) To provide technical bases for the goals are : development of policies for the future evolution of new satellite o Assure adequate protection is avail communication technologies with able, as warranted , against appropri significant public service benefits . ate threats for selected u.s. Govern ment , U.S. Government contractors , During FY 1979, the program was separated and private sector elements . into two projects , one addressing orbit/ spectrum capacity and regulatory aspects o Formulate a national policy on public and the second addressing public service cryptographic research. applications of satellite communications . These projects are discussed below. The second goal deals with the difficult area of balancing the private sector 's Frequ ency/Orbit Resource Study and Support right to pursue research in the area of of u.s. Proposals for 1979 WARC . The cryptography with the issues of national objective of these projects was to en security. Short-term objectives include courage the development of low-cost , small the development of a National Security and antenna earth stations in the fixed Implementation Plan based upon : satellite service through the development of technical and policy options and pro 1. Policy analyses concerning key posed rules relevant to the U.S. proposals issues and national impacts , and to the 1979 General World Administrative legal and regulatory require Radio Conference (GWARC ) and the 1983 ments . Regional Administrative Radio Conference . 2. System analysis to select a During FY 1978, work on the se projects system concept and recommend focused on preparation of the u.s. pro specific technical solutions posals through the IRAC Ad Hoc Committee consistent with available tech 144. The U.S. position document was nology , industry plans , and completed early in FY 1979. Although the effectiveness . formal proposals had been completed , technical analysis to support these pro 3. User-requirements analyses to posals has continued . These studies specify user protection needs, addressed proposed changes in the alloca user priorities, and vulnera tion of the 11 .7 GHz to 12 .7 GHz band . bilities . 84 The three related studies dealt with (1) SECTION 2.3. TERRESTRIAL RAD IO SYSTEM the increased orbit/spectrum capacity that PERFORMANCE would result from the proposed allocation changes, (2) the feasibility for spectrum This activity is directed toward the de sharing between broadcast ing-satellite sign , evaluation , acceptance , operation , services and terrestrial services in the and upgrading of existing or prop_osed sys 12 .2 GHz to 12.7 GHz band , and (3) the tems operated by the Federal Government . economic advantages and disadvantages The projects generally result in recom- " associated with moving the broadcasting mendations for systems design and/or up satellite service to the 12.2 GHz to 12 .7 grading as requested by the other Federal GHz band . Results of these studies were agencies . provided to the u.s. delegates to the 1979 GWARC . EFAS/PEP II Progr am . The EFAS program addresses the technical performance char Technical planning £or the 1983 Regional acteristics of the Digital European Back Administrative Radio Conference was initi bone (DEB) communications system shown in ated during FY 1979 . The purpose of the Figure 2-13. The DEB program is directed 1983 RARC is to develop a plan for the at the conversion of the wideband analog broadcasting-satellite service for Region communications systems to secure digital 2 of the International Telecommunication communications systems. An extensive Union . As a part of this study , a statis alarm , switching , and status remoting tical analysis was made of the orbit-slot system is imbedded in the new system . and frequency channel assignment plan for Regions 1 and 3 which was developed at the Alarm and status reporting and remote 1977 WARC-BS . The initial technical switching is controlled by one of three planning also included a review of computer minicomputers connected to the system that programs developed by others for analyzing are managed by application programs de proposed orbit-slot/frequency c�annel veloped by ITS . The computer system con assignment plans . trols polling of the remote sites and presents system conditions in a form most Public Service Communications . The objec useful to the system manager . The com tives of this project were to perform puters also archive all system changes for public service requirements and cost later analysis. Two of the display formats tradeoff modeling studies and to monitor are shown in Figu re 2-14 . the development of technology applicable to low cost earth stations for rural and The PEP II Program is undertaken to collect other thin-route satellite communications information on other parameters not associ applications . ated with the alarm and switching system . Among these will be rapid sampling of re On this project, ITS staff have partici ceived signal levels at a site that is one pated in the work and meetings of the terminal of a 160 km link . This path is Interagency Committee on Satellite Telecom known to have severe atmospheric layering . munications Applications . The National Also , station power will be monitored for Aeronautics and Space Administration reliability and channel block reliability (NASA) , as a contribution to the work of and availability will be evaluated . the Committee , developed a network costing model. This model was used to assess the EFAS/PEP II Progr am Analysis. The Digital cost of distributing a video signal from European Backbone (DEB) system contains Wa shington, DC , to 14 other major cities several links where propagation causes that have Federal office buildings in the some concern . It also has one site which downtown area . The resultant network has a severely restricted antenna mounting consisted of a satellite uplink terminal area and is one terminal of a 160 km near Washington linked to Federal Govern link which is known to occasionally experi ment departments via microwave relay and ence severe multipath fading . The maximum receive-only earth stations at each of the obtainable antenna spacing may be inade federal office buildings in the 14 cities. quate to realize the diversity reception needed on this link . In addition , the The ITS performed a cost analysis of a effectiveness and accuracy of monitoring terrestrial video distribution network technique s for digital equipment is still using common carrier facilities. The unproven on a system basis . results of these analyses show the cost of the satellite network to be about one This program is to address the aforemen seventh the cost of the terrestrial network. tioned concerns by acquiring propagation In the analysis of both networks, the data on the links that are known to have capital investment and installation costs severe atmospheric fading . Data will be were amortized over 10 years. collected on system availability and quality to assess system performance . Further, data will be collected to assess the effectiveness of the performance monitoring system . 85 GERMA NY AUSTRIA .... -..-_ ...... , , Cima Gallina y' ') •, I ' -----..... ""----...... Avlano ITALY • Adriatic Sea Mt.Cimone M�dit�rranean Sea Figure 2-13. Digital European Backbone System , Phase I. 86 212 () 4: 42: 4 5 t·l o Equi �nent Site An::.I.,J E· r Major Minor Major· Minor ParaMet er \·' f-It·{ n ·•3ETI .:,;-:�- \'o. j hi H::::T Hohen::;.·. ,o_dt. 0 ZUG Zu·':l:;:.�it ze ** C I M CiMa Gallin� ** F' AI� ' l •J * * PO. '':I IJ. I'"I E r·l CA rno' . ** lh Co i none· ** t'lTC t'l t C tt:: A Se· ** tH :· ro. CLO Colto. no ** i·1 t t·iTE \le· :··,do. • u ... c n . '*·* \·' CM • i E zo C E · ** G CE"':I'':Ii 0. A•.) i o. no ** R'·/0 FZM Friolzhe iM ** Ent e Cor••f'IO.nd: ,-. •.. ..- t" .:• I .:•. o e n a HST -H h st. dt Fi 1 o. i'"i'··; Sit e -MINOR- D��rouP HST-2: CL0-2 2 2.··' >::1 4 2 1 -STATUS-Tower Li�ht Disable 2 2 1 ..- ·'04 2 -STATUS-Rect ifier Sharin� Load ..... l 2 04 2 4 . -::: TI:n u ::>--- E:.. :r.:-o . n::. ion . . . .:: i 2 i ;� . 0·:+ .�·, .-, 2 -::: niHI ::: ·- FH::: TE:= t. .:: j �-� ,/ (1 "1 .-, ·:· -STATUS-Generat or NuMber On .:: 2 1 ::::.-·o4 -STATUS-Tower Li�ht On 2 ' 0 4 ·:· 1 ;2 .· -, : STATUS-Fuel PuMP NuMber 2 ..:: · · ,·'0 4 - On j �:: 175, 1 -ZUI�--!·1 I NOF:- o. ndb·/ t·1•.< :•< F•J. u l t 2 2 04 2 t·lD ::: 1. 1 -STATUS-Receiver A Se l ect 2 1 •')'- '0'i- .�::-, -:::TATUS-T c.:· i •.,.1 .;: l .:: .. .. .:: ro.n:= t· · 2 2 . E: D i :;:. (i . b ,.. , 1 04 M0559 .2-VHN-M INOR- TWT Failure .:: 8 :· l 2.··'04 2 -M I NOR- ExPans ion ·'"' 1 2.'04 9 · ·:· -STATUS-Receiver 8 Se l ect 1 2 . .... 0 4 2 2:· -STATUS-T ransceiver A Disable ·'- 1 2 ./(i .:� 2 AU1, HST Figure 2-14 . Sample enhanced fault alarm system displays . 87 The third minicomputer is to be installed to retain and improve their capability in and put in operation on the DEB system . HF digital radio communications . The The system software will then undergo objective of this project is to make a intensive testing . comprehensive survey of HF digital radio communication techniques to determine the Data obtained from the closely spaced best methods that might be used to improve diversity antennas are being analyzed and the performance and reliability of HF a letter report will be prepared for the digital radio systems . sponsor . Contents of this report are not to be made public without the sponsor 's A study was made of the specific design approval. features of HF digital radio systems that affect their performance. A basic HF RADC/Technical Support for the Air Force digital radio system consists of three Killer Kat Communications System . This major parts : the transmitter , the HF project was established to provide techni ionospheric channel , and the receiver . cal support and consultation to the Rome The performances of such systems can be Air Development Center (RADC ) in respect specified in terms of bit-error probability to the development of a special digital and spectral efficiency (information troposcatter communications system. ITS rate/signal bandwidth) . The bit-error personnel have provided review of technical probability performance of a system is test plans and have participated in program determined by the signal processing tech review meetings with the sponsoring agency niques that are used in the transmitter and the equipment contractor . On-site and receiver , and by the types and magni observation and consultation will be tudes of the distortions that are imposed provided later in the fiscal year when the on the signal by the equipment and the HF system is installed in Europe . channel . The spectral efficiency of a system is determined by the signal proces H.F. Ground Wave . The general goal of sing techniques and is independent of this prOJect is to determine optimum channel and equipment distortions . antenna aperture distributions for maxi mizing the ground wave field strength at The transmitter in general contains an distances beyond the optical horizon. The error coder, a modulator , an HF trans primary application is low-angle radar mitter , and an antenna . The character coverage over both land and sea . istics of the transmitter that affect system performance were considered in The feasibility of exciting the Zenneck detail by classifying and describing ; the surface wave was first examined . By types of error codes (block and convo matching either the vertical or horizontal lutional) ; the digital keying methods aperture field to that of the Zenneck wave (ASK , PSK, APSK, FSK , and CPK) ; the multi over a flat earth , it was found possible plexing techniques (frequency multiplexing to launch a Zenneck-like wave in the near and concentric multiplexing) ; the HF field. However , for antennas of realistic transmitter operation (frequency transla size, the Zenneck surface wave character tion, filtering , and amplification); the vanishes in the far field, and the remain size , gain , bandwidth , and steering char ing field has the usual ground wave char acteristics of a large variety of trans acter . Calculations were actually per mitting antennas ; and the additive , multi formed for both flat and curved earth plicative , and nonlinear equipment distor models and for both land and sea paths . tions introduced by the various parts of In all cases, the Zenneck wave excitation the transmitter . was found to be ineffective . The HF channel in general consists of a Surface roughness (land or sea) and sub number of propagation modes or paths over layering (ice or earth crust) can result which the signal travels from the trans in an inductive surface impedance which mitter to the receiver. Because the paths can strongly enhance the ground wave field introduce different propagation delays , strength . The curved-earth attenuation the channel introduces time-scatter multi function was calculated for a large range plicative distortion , and because each in amplitude and phase of the effective path introduces Doppler shift and Rayleigh surface impedance. Such calculations fading on the signal , the channe l intro cover all expected land and sea 'path cases duces frequency-scatter multiplicative of interest . distortions . Noise and interference that are present constitute additive channel Using the previous results for ground wave distortions . A validated HF channel model propagation and excitation, optimum antenna was used to characterize the channel . aperture distributions for both vertical and horizontal antennas will be determined . The receiver in general contains an an tenna , an HF receiver , a demodulator , and Performance Improvement of HF Communica an error decoder . The characteristics of tions . Because of the vulnerability of the receiver that affect system performance satellite radio to destruction under were considered in detail by classifying wartime conditions , the armed forces need and describing : the types of antennas 88 (including adaptive receiver antennas for Department of Energy as operator of the suppressing interference); the HF receiver SECOM system and manager of DOE sensitive operation (frequency translation , filter material transport operations, the Nuclear ing , and amplification) ; the types of Regulatory Commission (NRC) Technology demodulator filters (matched and non Assessment and Test and Evaluation Branches matched nonadaptive filters and quasi of the SAFEGUARDS Division . In addition , static and dynamic adaptive filters); the a transportation service contractor will bit-decision or detection methods (coher participate in the evaluation. Test ent , partially-coherent, differentially direction is the responsibility of the NRC coherent , and noncoherent); the types of Test and Evaluation Branch . error decoding (hard and soft) ; and the additive , multiplicative , and nonlinear ITS has developed the test methodology and equipment distortions introduced by the a detailed test plan . The methodology various parts of the receiver . Also identifies specific communications and classified and described were the types of operations event relationships for selected diversity operation : single-transmission route profiles and provides event temporal polarization and space diversity; multiple and connectivity sensitivities as derived transmission frequencies and time diver from existing operational and functional sity; and performance monitoring and models. Commun ication elements include prediction methods . SECOM and intra-convoy modes. Mission operations include pre-mission system The bit-error-probability performance of entry at departure sites, enroute status a system with respect to the various types reporting and incident events , and clear of channel and equipment distortions are ance reporting at route termination . The affected by nine system design features : detailed test plan specifies mission the fundamental pulse waveform, the keying planning procedures, data recording methods method , the multiplexing method, the type and analysis processes , appropriate system of demodulator filter , the bit-decision diagnostics , and convoy crew and intruder (detection) method , the transmitter power , force training requirements. The test the antennas, diversity, and error coding . plans and test procedures are designed to The spectral efficiency of a system is determine the performance of the HF determined by the first four and last two communications system under three con of the same design features. The effects ditions ; namely : normal transport condi of the system design features on bit tions , unintentional accident , and physical error-probability performance were evalu threat (equivalent to airline hijacking or ated with respect to additive channel and terrorist) . In the latter case, the · equipment distortions , multiplicative scenario of the simulated threat , which is channel and equipment distortions , and considered to be non-military in nature , nonlinear equipment distortions in turn . has been defined and sources of public The. effects of the system design features information available to such counter on spectral efficiency were evaluated in forces as well as the types of military conjunction with the evaluation of the surplus·jamming equipment available to an bit-error-probability performance . The informed adversary have been identified . results of the evaluation were then used to determine the best methods of improving Using these test plans and procedures, an the performance and reliability of military actual simulated communications counter HF digital radio communications. A final measure event will be staged to determine report was prepared that describes the the vulnerability of the communications study and presents specific conclusions system to such intentional jamming . ITS and recommendations [Watterson , C.C. , will participate in a DOE/NRC planning Methods of Improving the Performances of ses sion and serve as a technical advisor HF Digital Radio Systems , NTIA Rept ., 1979 and resource in the planning of this test. (to be published) ]. The tests will actually be performed by DOE contractor personnel with the counter DOE SECOM Technical Support . This project force being suppl ied by u.s. military supports the ERDA Material Transportation personnel who will be given the informa SAFEGUARDS programs with the major thrust tion which ITS has generated and resources concern ing systems engineering support to to develop the communications counter evaluate the capabilities and vulnerabili measure system from commercially available ties of the existing SECOM system to equipment. support communications with commercial trucking systems transporting nuclear Digital Sys tem Performance Verification . material . The program was initiated in The U.S. Army Communications Command FY 76 and concerned the development and (USACC ) at Ft. Huachuca , AZ , found it implementation of an improved HF propaga necessary to convert two 4-5 GHz trans tion model, mobile antenna evaluation , and horizon transmission paths from analog-to the initial design of a system management digital operations . A DCEC Technical model . Report describes the bit-error performance expected of a transhorizon digital system. During this fiscal year, ITS has partici However, the prediction models used are pated in an evaluation program which in based on models contained in NBS Technical volves three Federal agencies : The 89 Note 101, or variations of this model. where the performance improvement they The Technical Note 101 model was developed provide is·.in addition to , and in some from measured data concentrated in the 40- cases much greater than , the usual chip 1000 MHz frequency range . The prediction processing gain. The improvement in associated with using frequencies outside receiver performance that an adaptive the actual operating range is discussed in filter can provide depends on the ratio of Vo lume II of NBS Technical Note 101. the bandwidth of the modulation on the interference to the bandwidth of the A method for reducing the performance spread-spectrum signal . With CW interfer prediction uncertainty by decreasing the ence , the bandwidth ratio is zero , and the width of the confidence interval is improvement is ideally infinite . For available and it makes use of measured other types of interference , the improve data . The measured data are particularly ment decreases and the bandwidth ratio valuable if the data are obtained on the increases, with relatively little or no actual transhorizon path . improvement remaining when the bandwidth ratio approaches one . Path-loss data were obtained from a 60-day measurement program on the two transhorizon Prior to FY 79, an experimental adaptive paths . The hourly medians were combined , filter, based on a relatively simple for each path, into a cumulative distri delay-line model, was designed and built. bution of hourly medians , and calculations It was temporarily incorporated in a U.S. were made using these data to decrease the Air Force 616A VLF-LF spread-spectrum width of the confidence limits . The total digital radio system , and channel-simu width of the confidence limits were de lator experiments were performed on the creased roughly 9 dB for each path . mod ified system to determine the perform ance improvements provided by the adaptive The improvement in the confidence of filter . The expected substantial perform performance predictions led to suggesting ance improvements were observed in the that the link performance criteria for experimen·t s, wh ich also confirmed the these paths could be met by replac ing the expectation that dynamic nonlinear opera present waveguide with new types having tion of an adaptive filter can provide half the attenuation and realigning the greater performance improvement than obviously poorly pointed antennas. This quasi-static linear operation . During FY resulted in discarding any thoughts about 79, a classified report was prepared on increasing the power amplifier output the design and characteristics of the power from 1 kW to 10 kW , a significant adaptive filter and the results of the reduction in co st. channel-simulator experiments [Watterson , C.C., An adaptive receiver filter for SECTION 2.4. SIMULAT ION AND STANDARDS interference suppression in digital spread spectrum radio systems (U) , NTIA Technical Radio system simulation and standards Memorandum 79-9C, 142 pp , February 1979 (including handbooks and glossaries) are (Secret) , u.s. Department of Commerce , combined in this program element . Simula Boulder , CO 80303 .] tion provides a realistic and repeatab le method for evaluating and comparing the DCS II Standards Development . This pro performance of different subsystem elements gram was contracted to ITS to provide (e .g. , modems) on an ob jective basis. technical assistance to the Defense Communi cations Engineering Center (DCEC) for MEECN Simulation . The present obj ective identifying areas where standards are of the proj ect is to comp lete the devel required f9r the DCS II program . The FY opment and evaluation of an experimental 79 effort is to evaluate evo lving commun i adaptive filter that can be used in cations technology , review standards, digital spread-spectrum radio receivers to define functional standards are as , and suppress interference (unwanted signals) . define one major function area for investi gation in regard to the functional area Mo st dig ital radio systems use nonadaptive selected . ITS will identify standards (time-invariant) receiver filters , usually requirements, look at cost impact, assess matched filters that optimize the receiver feasibility , and recommend standardization performance with respect to white noise . action . Matched receiver filters generally provide suboptimum performance with respect to FED-STD-1037 , Vocabulary for Telecommun i interference ; however, generally better cations . This comprehensive glossary of performance can be obtained with an adapt telecommun ication terms and definitions is ive filter that automatically adapts or the result of a joint effort by numerous adjusts its response , according to the DoD and non-military Federal agencies . It characteristics of the interference , to will serve as the nuc leus of a commonly maximize its output signal-to-interference agreed upon language for both the MIL-STD- ratio . As described in more detail in ITS 188-100 and the FED-STD-1000 series of Annual Technical Progress Report for 1978, system performance standards . adaptive filters can be particularly effective in spread-spectrum receivers 90 The initial data base for the glossary was mobile services, as detailed in the MARAD MIL-STD-188-120, Military Communic�tion Assistance program description appearing Standard : Terms and Definitions, edited in Section 2.1. by ITS and pu blished in 1975. This portion of the vocabulary has been extensively SECTION 2.5. FIBER OPTIC COMMUNICATIONS reviewed and updated by DoD agencies in order to keep abreast of advancing tech ITS has had an activ e role in the rapidly nology and continuing revisions of the growing field of fiber optics communi MIL-STD-188-100 series . cations. This role has included such activities as publishing a fiber optics Primary additions, consisting of over 700 handbook , organizing and chairing an Ad new terms and definitions, carne from the Hoc Optical Communications Task Force , Federal sector. Many were drawn from providing consulting services in fiber evolving federal performance standards optics to the Department of Defense , such as FED-STD-1033, Telecommunications developing a data base for an optical Digital Communications Performance communications glossary , and sending the Parameters . These new data were added to Chief U.S. Delegate to the International the computer-stored MIL-STD data base to Electrotechnical Commission Subcommittee produce a draft of approximately 2000 on Fiber Optics. These activities are entries. This draft was distributed to 75 discussed in detail below . reviewers within the DoD and Federal commun ities. Reviewer inputs were consid Optical Communications Task Force. Prior ered by a joint DoD/ Federal Resolution to 1970 , optical fiber "light pipes" Subcommittee of the Federal Telecommunica fabri cated from commercial grade optical tions Standards Committee , meeting in two glasses yielded tran smission attenuation 2-week sessions in late FY 78 . ITS was a typically ranging from BOO to a few 1000 participant in both sessions and has been dB/krn , precluding their use for any responsible for incorporating the extensive practical communications applications. In editorial modifications into the draft that year , the first low-loss optical document. ITS is currently engaged in fiber waveguides , fabricated from ultra final corrections to the revised glossary pure fused silica , were successfully and in a comprehensive cross referencing produced by a U.S. manufacturer . Attenu of the integrated document . Publication ation was measured , in the laboratory , at is scheduled for early FY 80. This work approximately 20 dB/krn . It was almost has been funded by the National Commun i another five years before the first such cations System and the u.s. Army Communi low-loss optical waveguide was made cations Command/Communications-Electronics available (on special order , in custom Engineering Installation Agency (USACC/ production) in cable forrn-�by the same CEEIA) , and coordinated via The Standards domestic firm . In 1979, dozens of manu Branch of CEEIA . Figure 2-15 summarizes facturers in the u.s. and abroad offer , as primary tasks involved in creation of this commercial shelf items , a broad variety of Standard , as we ll as current status of optical waveguide cables . Laboratory the various tasks . measurements of uncabled fibers are currently as low as or less than 1.0 ITU Participation . T. de Haas, Chairman dB/krn , and cable attenuation , after of the u.s. CCITT Group for Data Trans systems deployment, runs as low as 3 or 4 mission , led U.S. participation in CCITT dB/krn . The guided wave optical trans Study Groups VII and XVII. Some of the mi ssion line has technically come into its notable outputs from these Study Groups own as not only a practical , but an are a world-wide numbering plan for data extraordinally efficient , commun ications networks which also includes capability medium . The worldwide operational success for interconnection between data- , tele of hundreds of systems attests to the phone-, and telex-networks, a new Recom simultaneous rapid development of optical mendation for 1200 bps duplex moderns for sources, detectors and other systems use on the public switched telephone components . network , and several new and updated Recommendations relating to packet switched Parallel with this technological evolution data services. has been the activity of the Optical Communications Task Force (OCTF) formed by In the CCIR, Mr . de Haas is International ITS in FY 75 . Creation of the Ad Hoc Task Chairman of Study Group 3, dealing with Force was in accordance with the OT radio systems in the Fixed Service oper mission " .•. to assist the Department of ating at frequencies below 30 MHz . He Commerce in fostering , serving , and also participated and was a Topic Coordi promoting the nation 's economic develop nator in the Special Preparatory meeting ment and technological development by of the CCIR which prepared the technical promoting man's comprehension of telecom bases for the 1979 World Administrative munication science and by as suring effec Radio Conference . ITS is also contribu tive use and growth of the nation 's ting to the work of Interim Working telecommunication resources ...." Continu Parties (IWP's) 8/5 and 8/8 in the maritime ation of the Task Force work is in support 91 Initial data base : New Federal community inputs , MIL-STD-188-120, including vocabulary pertinent Military Communication Std. : to FED-STD 1000 series Terms & Definitions (prepared by ITS , 1975) ITS integration and __, computer storage of 200 0-term draft Individual revie! w and comment by 75 FTSC* members Review & resolution! of draft and comments by joint Federa l/DoD FTSC Subcommittee (ITS participant ) -} ITS edi torial preparation of final revised document I ---J ----- I I *Federal Telecommunications Legend : Standards Committee work comp leted work in progress future work Figure 2-15 . Status of FED-STD-1037 , Vocabulary for Telecommunications . 92 of the NTIA mission of serving as a nation providing a forum wherein such interchange al focus for Fed eral policy and decision does take place and where potential making in those areas vital to the Nation 's policy issues , as well as avenues of economy in this new Age of Information. technological development , may be identi fied . The OCTF was developed to provide an informal , interactive forum among govern The two FY '79 Working Group meetings have ment , university, and industry tech nolo covered a broad range of topics including : gists , potential systems users, and policy component development ; experiences in makers in order to explore jointly the various physicaL types of installations of technological and economic potential of optical transmission lines; computer optical communications applications . The interfacing ; integrated optical circuits ; emphasis of the Task Force is now on need for and progress in standards; alter guided wave technology , as the result of nate configurations of optical data buses ; the growth of its varied and successful user needs , in'cluding th ose · of the Federal system applications. Optical transmission government and the DoD ; descriptions of through the atmosphere has also advanced trial and operational systems ; and discus remarkably within the same past few years , sions of economic factors and the impact but applications have been more limited of potential policy and regulatory deci because of both bandwidth and range re sions . strictions imposed by an often hostile environment . Optical Waveguide Communications Glossary. The rapid emergence of optical fiber wave In the coordination of the OCTF , ITS has guide communications from the laboratory assumed a catylytic role with other into commercial systems applications has Government agencies in the evaluation of been accompanied by the growth of a spe this new technology by interagency parti cialized vocabulary. Some terms have been cipation in semiannual workshop sessions , borrowed freely from the disciplines of augmented by ITS preparation and distri optical ph ysics and communications engi bution of Summary Reports of presentations neering; others have been coined indepen given during the meetings of the OCTF dently. Applications and Users Working Group . In this process, inevitably, some ambigu These Working Group meetings have been ity and impreci seness have resulted . More consistently we ll attended by senior significantly , perhaps , some terms have represent ation from industry , leading been used to sp ecify a product--and are universities, and government , including beginning to be accepted by manufacturers the DoD . Task Force participants have and users--but are not precise descriptors benefited from the informality of the beyond rather narrow limits. The absence working Group . This often has resulted in of a precise , common language among re the early and opportune dissemination of searchers , manufacturers , systems design technical information and product avail ers , a nd users is a hindrance to effective ability , and also in the open discussion technology development and utilization . of economic aspects that are infrequently The need for such a common language has introduced in formal communications become pronounced as numerous standards society meetings . One such topic surfa ced working groups in both government and the during the first Workshop meeting in FY private sector , nationally and inter 79. The representative of a u.s. system nationally, have become engaged in prepar manufacturer presented a summary of his ation of performance standards covering firm's product line , emphasizing that "the components and sy stems . technology is ready" for volume production , but that their market analysts were unable In recognition of this need , ITS compiled to predict a near-term market adequate to a preliminary vocabulary data base during justify those costs required to tool up FY 1978 . This effort has been continued for mass production . This presentation throughout FY 79, attracting broad interest was followed by that of a representative and technical support from outside individ of a leading domestic producer of (un uals and organizations . Early in FY 79 , cabled) optical fiber waveguides , who ITS enlarged the initial data base , announced that his firm' s mid-1978 sales writing definitions for numerous terms volume had reached the level previously commonly employed in optical communications predicted for 1980. Workshop participants but not conc isely defined in the litera found these two statements paradoxical , ture . This initial draft was computer asking the fiber manufacturer where his stored to facilitate text editing during market was , in view of the pessimistic the anticipated several generations of outlook for dome stically-produced systems . review and revision . At this time , it was The reply was : "Germany , It.aly, the U.K. , decided that the scope of the glossary- France , and Japan. " Various conclusions and the accuracy of its defi�itions--would may be drawn relative to potential effects be augmented by contributions from physi upon u.s. balance of trade ; the point to cists with backgrounds in measurement be made here is that the OCTF is fulfilling standards, to complement ITS experience in the Department of Commerce mission by communications engineering . As the result , 93 two NBS scientists, both actively engaged Optical Waveguide Transmission System Engi in optical measurement studies, were added neering. ITS has continued its catalytic to the editorial staff , thereby creating a role in fiber optics technology by inter joint ITS/NBS effort . acting with the technical community at large . A small project has resulted in a Individual contributions from this group study (and publication) which attempts to of editors were added to the initial evaluate the U.S. position relative to draft , and the revised document was foreign competition in capturing a fair critically reviewed during numerous share of the world market in fiber com interactive meetings of the editors. munications components . The study is Selection of terminology was deliberately based on active participation of the restrictive , with the goal of including leading countries in publishing , capturing only terms specifically applicable to the patents, and presenting technical results field--and of defining those terms rigor at international meetings . The results of ously. This definition process entailed the study show that Japan is a strong some subj ective decisions , a few of which competitor , and the relative position of are anticipated to create controversy . the U.S. and Japan is reminiscent of the TV industry a few years ago . After completion of ITS/NBS review , the first external release of the glossary was In another small project, we assembled as a draft input to the ITS-chaired North data on fiber optics installations in American Advisory Committee of the Joint North America and Australia and the results CCITT/IEC Working Group "0" on Definitions were combined with similar data from and Terms for Fiber Optical Communications. Europe and Japan to yield a survey of world-wide fiber installations. The This Advisory Committee consists of u.s. results were presented in a plenary paper and Canadian representatives from private at an international meeting in Washington industry and government (including ITS and and have been presented for publication in NBS) , all active workers in the field of IEEE Spectrum , a publication having a optical waveguide communications. This circulation of about 180 ,000. The study committee subjected the draft to further attempted to alert potential users of new review and expanded its scope by inclusion systems to the problem encountered thus of additional terminology pertinent to far and the solutions that seem to be component manufacturers and systems working in the field . Concentration in performance standards groups. the North American survey was on non government installations. The resultant document , therefore , reflects the experience and backgrounds of a select A small proj ect , which is just being group of professionals with widely varying started as FY 79 draws to a close , is the expertise in the field . The glossary is development of a user-oriented software currently in the process of publication as package for desk-top mini-computers to an NTIA Special Publication . It will have analyze and synthesize fiber optic systems . been presented (Sept . 1979) in Amsterdam , The Netherlands , by the (ITS ) Coordinator The program will operate in a menu-drive of the CCITT/IEC Advisory Committee as the mode , allowing for use as a learning tool coordinated North American (U.S./Canadian) when the need is apparent . If the user is Position on Vocabulary to the first inter familiar with component specifications , national session devoted to creation of the tool can be used for complete analysis standard terminology for the field . It or synthesis (including proposal evalu will also have been submitted , by request ations) of fiber optic systems . of the IEEE Standards Office , to IEEE Standards Committee 10 for publication in The IEEE Standard Dictionary Series . Requests have been received for distribu tion of the NTIA Special Publication to numerous performance standards working groups including EIA P6 .6 on Fibers and Materials, CCITT Working Group 15 on Standardization of Fibres , IEC Working Group 1 on Fibres and Cables, and IEC Working Group 46E on Fibre Optics. The glossary will be submitted at the approp riate time for inclusion in the first revision of FED-STD-1037 , Vocabulary for Telecommunications (also prepared by ITS) . The block diagram of Figu re 2-16 summarizes the evolution of this glossary and its planned distribution. 94 ITS literature search/compilation of data base ITS preparation of initital draft/computer storage -v Review/addition of new data: joint ITS/NBS editorial staff Further review/expanded scope •-t• of draft: ITS-coordinated North American Advisory Committee of Joint (CCITT/IEC ) Working Group "O" on Definitions and Terms for Fibre Optical Communications � IT S editoria l preparation of revised document J r ______, f_ -L- r--:- - -, - Public tion as NT IA 1 Submission as the forma l Inqu1ry fro__t_m IE£E I,Fu ture-- submi ssion:1 I ';l 1 j__ Spec1al Report coordinated US/Canadian Standards Commi ttee I 1 to FTSC for I Position to Joint 10 regarding sub- inclusion in ' 1 1.0 - (CCITT/IEC ) Working ' mission for publi- 1st revision of U1 I Dis tribut o; to --=-- Group " 0 " on Definitions ' cation in Standard FED-STD-1037, � include various U.S. I & Terms for Fibre Dictionary Series I Vocabulary for I -- t � L ------' Working Groups on Optical Communications, ommunications C _ optical waveguide for international _j performance stds. , negotiations e.g. , EIA P6 .6, I ______CCITT 15 and IEC 1 , , I _j_ 1 and 46-E Continued participation 1 _j I L------in international evolu- 1 I tion of a Standard Vocabulary 1 L ______.J Legend : Work comp leted Work in progre ss Future work Figure 2-16. Status of glossary on optical fiber waveguide communications. CHAPTER 3. EM WAVE TRANSMISSION in engineering tools. Predictions of transmission characteristics and system The ground , the atmosphere , and the iono performance are discussed in Section 3.4. sphere degrade radio waves in varying de Section 3.5 reports on applications of the grees , depending on circumstances . It is knowledge and tools to specific problems the purpose of the EM Wave Transmission of other government agencies , such as mine Program to study these effects and pro and forest service communications . vide models to the system designer that wi ll aid him in providing more cost effec SECTION 3.1. WAVE TRANSMISSION tive and spectrum efficient designs . The CHARACTERISTICS phenomena which cause these detrimental effects on radio and optical systems are , Experimental determinations of the effect in general , frequency dependent ; therefore, of the transmission media on electromag specific studies and tests are required netic wave transmission are reported in for specific frequency ranges and appli th is section, in particular those effects cations . produced by the atmosphere . Some of the phenomena which effect radio Multipath Fad ing. Radio signals in the signals and are studies in this program mm/cm wavelength range are subject to are : severe fading (e.g. , > 30 dB ) on terres trial paths of a few tens of kilometers 1. Attenuation by atmospheric or more. Such fading is in addition to gases , hydrometeors (rain, snow , hail , attenuation by rain and is often omitted clouds , etc.), or ionization. from consideration in point to point link design . These amplitude variations through 2. Scattering by hydrometeors or clear air may be caused by : irregularities in the refractive index of the lower atmosphere or ionospher�. a. phase interference from surface reflections ,· 3. Refraction, ducting , and multi path , resulting from atmospheric or iono b. misalignment of the antenna beams spheric layers. by refraction , 4. Dispersion , resulting from fre c. focussing/defocussing of the quency dependent properties of the atmo beams by refraction , or sphere , ionosphere , and earth . d. atmospheric (surface and/or 5. Scintillation of amplitude , elevated) ducts , one of the more phase, polari zation, and angle of arriv complicated fading mechanisms to al , resulting from turbulence and irregu investigate and possibly the lar structure in the atmosphere and iono main mechanism for fading on LOS sphere . links . 6. Reflection, scattering , multi The objective of th is program is to provide path , and lower atmosphere perturbations an improved model for understanding the resulting from terrain and man-made physical mechanisms of the amplitude and structures . phase o£ the received signal for systems expected to experience non-rain fading . The effect upon any specific system of the above phenomena is not only highly An example of the potential fading from frequency dependent, but is also depend phase interference is shown in Figu re 3-1 ent upon the type of service required for for a system at 30 GHz having a surface- the specific application. reflection coefficient of 0.95 at mid-path . Antenna heights are equal and the abscissa One driving force behind the EM wave trans ( �og scale) is the ratio of the depression mission program is the need for more spec angle (to the reflection point) to the trum space. Therefore , this program pro (equal) antenna beam �idths . The curve vides models , techniques, and information labelled R is the ratio of the amplitude to aid the system designer and frequency of the reflected and direct signal compo manager in their decisions for better spec nents . The two curves FE show the fading trum use . · "envelope" corresponding to the extremes of in- and out-of-phase conditions for the Experimental or theoretical determinations two components , and FR is the difference of radio wave transmission characteristics, between these extremes , i.e. , the potential or the channel transfer function, are re fading range . For a path of 25 km (at ported in Section 3.1. Measurements of 30 GHz) , a change in refractivity lapse transmission media properties and analyses rate of only 8 N/km could produce a fade of collections of such data are included equal to FR. in Section 3.2. Section 3.3 describes the development and testing of models wh ich Measurements of fading are being made on incorporate the transmission information a 23 km path at 9.6 and 28 .8 GHz from the 97 I I I I I I I I 1.{') m 0 �l' II ,, (...) II II C\ ,, 0 � 0 II I-, I \ \ I \ I \ · ...... - \ 1 0::: . / I \ \ ,.,../ I ' . /. I I /.t("' I / ' / ' I , I I ' I ' I ' I . ,/ 1/ 0::: Q (\J ol d O::: OJ 0 0 0 0 W"'C 1.{') !'() (\J 0 WOJ 0 0 0 0 LL."C � !'()I v I I Figure 3-l. Effects of path/antenna geometry on received signal with phase interference by one ground reflected component. Amplitude of resultant signal : R; envelope of maxima and minima : FE ; fading range: RF . Abscissa is ratio of depres sion angle of reflection point to antenna beamwidth. 98 Radio Building to the Boulder Atmospheric perature and water vapor . In all cases it Observatory of NOAA near Erie , Colorado . is essential to have accurate knowledge of The transmitters are mounted on the ele atmospheric EHF characteristics , in partic vator of a 300 m tower . This permits ular , to be able to predict their vari he ight-gain measurements which give infor ability with weather , location , and height. mation about surface reflection coefficient and location . More importantly , this path Atmospheric propagation effects inherent will allow a determination of the effec to the gaseous atmosphere are of foremost tive earth's radius and thereby provide a importance since they are always present. calibration on possible measurements of EHF applications are dependent on a de refractive index and its gradient. The scription of the somewhat complicated path profile (for an effective earth interaction between millimeter waves and radius factor of k = 4/3 ) is shown in the mo lecules that comprise the atmosphere . Figu re 3-2 . The path passes over a rela The purpose of the work was to translate tively thin ridge which is expected to molecular spectroscopy into an engineering minimize surface reflections and act as a data base which can be readily applied to diffraction edge. Figure 3-3 shows a ray generate attenuation , phase dispersion , trace for a duct having a gradient three and emission properties for modelled radio times the critical value (i.e. -471 paths within , into , and through the neutral N units/km) . The transmitter could be atmosphere (h = 0 to 120 km ) . located within the layer while the receiv er is located below the layer . This is an The relatively stable air mass of the obvious example where ray tracing would first hundred kilometers in altitude h is fail to predict the signal strength and a unique filter and generator in the EHF where a full wave solution is required . band with transfer , shielding , and emission Figure 3-4 compares the measured data with properties not found at any lower frequency. the results expected from knife-edge dif Mo lecular absorption spectra of major fraction theory . (O z , H 2 0 ) and minor (e .g. , Os , CO , NzO) air constituents cause frequency-dependent The receiving terminal is presently being signal attenuation , phase delay , ray moved to the ITS Table Mountain field site bending , and medium noise. It is possible (north of Boulder) to provide a path which to predict such behavior for a radio wave is expected to include a significant sur traversing a clear , inhomogeneous atmo face reflected component . The planned sphere if the physical parameters [height experiment will include measurements of profiles of pressure p(h) , water vapor refractivity gradients in the path vicin den!;lity p (h) , temperature T (h) , and trace ity by microwave refractometers on the gas number densities y. (h) , and geomagne tower and flown in a small aircraft. tic field strength H] �long the radio path are known . The interaction between radia SECTION 3.2. CHARACTERISTICS OF THE ti.on and air is expressed through a com TRANSMISSION MEDIA pl�x refrac tivity This section is concerned with the study N(v, p, T, H, ) p, Vi of transmission media to help those who design , construct, or use telecommunica The N-calculation takes into account 36 0 2 tion systems to better understand the lines , 6 HzO lines plus a nonresonant spec characteristics of the media and their trum , and if needed , includes a data base effects on radio signals. We first dis �or trace gas spectra (� 100 Os , 2 CO , 64 cuss the nonionized atmosphere and then N 2 0 lines ) wh ich are generally weak . The the ionosphere. �alculation scheme has been verified to a large extent by laboratory measurements . 3.2.1. Atmospheric Characteristics An uncertainty remaining is the empirical prediction of anomalous water vapor absorp Modeling of EHF Propaga tion in Clear Air. tion , which reduces at high relative humid The number of millimeter wave systems ities the transparency in the window ranges operating through the atmosphere in the (centered around 40, 90, 140 , 220 GHz) . EHF band (30-300 GHz) is growing rapidly, in part due to their ability to penetrate Various computer calculations of molecular smoke , dust, fog , clouds , or light rain, transfer characteristics were performed wh ich gives them an advantage over infra using numerical approximations for the red and electro-optical devices for ad cumulative behavior along slant paths . verse weather applications . Areas where Results from these modelling efforts are EHF systems are a logical choice include depicted in Figu re 3-5. broad bandwidth communications , surveil lance radars with high spatial resolution , USAF-ESD/AN/TRC-170 Digital Trope Tests . space radars with the possibility of This project was in support of the Air ground-clutter reduction by molecular Force Electronic Systems Division . The absorption shielding , strato-mesospheric objective was to perform path-loss and trace gas studies from SPACELAB , and delay- spread measurements over a number of satellite meteorology where radiometry designated troposcatter paths in southern provides global vertical profiles of tern- Ar i zona . The particular paths were selected 99 300 - 1/) '- Q) - Q) E 200 - w - (f) 1/) '- <( Q) - (J) Q) E 1700 a:: - 100 w - � 1/) 1650 0 E 51 1- w > w 1600 > 0 0 _J (J) w <( 1- ::X: (.!) 1500 w -100 ::X: 0 22.8 Radio Bldg. Erie (SAO) KILOMETERS Figure 3-2 . Profile of Radio Building/BAO Tower for k = 4/3 sh owing diffraction ridge . 1700 ...... -- - 471 N Units/km direct Thickness =50m "' ... Q) Q; ....-- - 40 N Units I km : � � : . 1500 . . . 1400 5 10 15 20 0 First Try 22.8 km 30 35 Radio Bldg Erie Kilometers F�gure 3-3. Ray tracing for layer with ducting gradient of -471 N/km . 100 • • • -200 100 DISTA NCE BELOW • MEASURED SIGNAL LEVEL WITH GRAZING (m) REFERENCE TO ARBITRARY SCALE f-' 0 f-' Figure 3-4 . Example of measured data at 28.8 GRz compareq w�tA res·ults expected fr� J<,nife-eqge diffract�_on th�ory . 10 · I 5 1- 2 E � ...... en "'C ...... t1 0.5 c: 0 - 0 ::J c Q) 0.2 - - <( 0.1 0.05 � h =30 /km""--ll...Jl.j.....,.,. 27 0.02 0.01 �I.-L....I�...... L....JI..I.U..U..III.I�...J...... L..�.1...... J...-&JL..II.U,J�-J-.J 45 50 55 60 65 70 115 120 Frequency, GHz Figure 3-5 . Molecular (mainly o2) attenuation rates at four he ight levels between 0 and 30 km for medium (R. H. = 50%) humidity . 102 by the Air Force Tactical Communications Four radio paths were tested in the pro Test Office with support of the MITRE gram , ranging in length between 38 and Corporation at Fort Huachuca , AZ . The 140 miles . The probable propagation paths were chosen as potential test paths mechanisms included diffraction as well for the AN/TRC-170 Tactical Tropo Equip as troposcatter . The experiments were ments being developed under the TRI-TAC performed during January and February , Program. Full field test and evaluation 1979 , spending approximately one week on programs for the AN/TRC-170 equipments are each path . Data were obtained almost expected to begin in fiscal year 1980 at continuously in order that diurnal effects these locations . could be determined . In general, each path proved to be acceptable for the The purpose of the measurements was to pro future AN/TRC-170 test program , under the vide a "calibration" of the path loss and criteria established for the propagation delay-spread parameters of each path, to conditions , and specific test plans can ensure that they were not beyond the de be finalized based on the measurement sign specifications imposed on the devel results . Delay-spreads on the average opers of the AN/TRC-170 systems . The ranged from 0.3 to 0.5�s, with longer equipment configuration used an AN/TRC-97A spreads of 0.8�s for shorter periods of analog troposcatter system as the host time . These values are given in terms of radio , which was furnished by the USAF . the 2a values of the distributions , The radio equipment wa s installed and assuming a Gaussian function. The analy operated by the 3rd Combat Communications ses were made using a time-series computer Group from Tinker AFB, OK . The delay that measured the distribution of the spread parameter was measured using the impulse width . The maj ority of the func ITS Psuedo-Random Noise (PN) Channel Probe . tions displayed a Gaussian character , with The latter is an instrument designed to the exception of the path that contained a measure the effective impulse response of strong diffraction component . An example a radio transmission channel. A PN test of the impulse response measured over one signal, generated in the form of a binary of the test paths is shown in Figure 3-6. data stream is used to bi-phase modulate The photograph wa s made from a display on an IF signal in the transmitter , and is a storage oscilloscope with a few seconds then mixed with the propagating frequency . ttme lapse. It illustrate s the time vari The receiver of the system uses a mu lti ability of the response. plex type correlation detector (in each of two channels) , and develops the equiv Path loss measurements and predictions alent low-pass impulse response by corre were comparable for two of the paths lating the received data stream with a tested . However , all of the data pro locally generated replicum of the trans cessing was not completed at the time of mitted code pattern. The probe was de this report , and thus no detailed compari signed for application in both microwave sons were possible. A final report on the LOS links and troposcatter circuits . The project will be published in the final PN code may be clocked up to 150 MHz , pro quarter of FY 79. viding a time resolution on the order of 6ns . However , for the troposcatter mea Rad io-Optical Refractometer. In the atmo surements the clock rate is generally held sphere , microwave signals propagate slower to 10 MHz, so that the signal BW is com than optical signals , due principally to mensurate with the capabilities of the the effect of water vapor . Measurements transmission system . In this case, the of the difference in velocity over a trans time resolution of the impulse measure mission path can be used to calculate the ment is on the order of 0.1 �s. For high total amount of water vapor along the path . clock rates , the IF is 600 MH z, whi le at For a path of 10 km through saturated air the lower clock rates and for interface at sea level , the difference in transit with existing radio systems , a 70 MH z IF times for a 10 GH z J3 em) microwave signal signal is used . The latter configuration and a 475 THz (6328A) laser signal is about was used in th is program so that a direct 3 ns. interface with the AN/TRC-97A radios could be effected . The final amplifier stages To estimate the integrated water vapor of the transmitter were carefully tuned density to 1% thus requires measurement to accomodate the broadband PN test sig of the differential transit time to 30 ps. nal . The transmission frequency for the This accuracy can be achieved by measuring tests was in the tuning range of the the phase difference between a 100 MHz TRC-97A system , between 4400 and 5000 MHz. sinusoidal modulation on the laser beam Calibration for the received signal level and a 10 GHz signal generated coherently (RSL) was accompiished with a calibrated from the 100 MH z oscillator and trans signal generator at the rf input to the mitted over the path . This method was radio receivers. The generator frequency demonstrated on a 45 km path with fixed was ad justed with the aid of a frequency terminals in 1967 and patented in 1969. counter that monitored the IF at 70 MHz. All of the data were recorded on analog magnetic tape . 103 I-' 0 ""' t 0 0.2 0.4 DELA¥ - }lS. Figure 3-6 . An example of the power impulse resp on�e mea,s�red over a lQ.Q f£1tle tro�o?catter path in southern Arizona. The log respons-e ;functton· s])pws received. 1?ower spread to delays of 0.4 ]lS peyond the initial reSJ?Gns-e . The objective of the present project. is Intervisibility Propagation Loss Measure to examine the feasibility of maintaining ments . A study was conducted to determ1ne useful accuracy in a system where one what the limiting propagation effects are terminal is mounted on a small aircraft or on the performance of a microwave system helicopter . The immediate application that could be used to detect when two vehi would be to calibrate millimeter-wave cles , separated by up to 10 km, are opti radiometers used in earth strain measure cally visible to one another in irregular , ments . The principal problems appear to obstructed terrain. The study objectives be engineering problems associated with were to : 1) demonstrate what effects sig maintaining adequate optical alignment nal variability has on the intervisibility between the airborne and ground terminals . decision process; 2) identify the possible Re sults to date indicate that the techni sources of the signal variability and to cal problems can be solved , but the ques estimate the magnitude of each source 's tion of cost is not yet answered . contribution to the total variability; 3) obtain propagation loss data , over Navy Refractivity Study. Anomalous fea various types of terrain and obstructed tures in the vertical profile of atmo paths , which could be used to predict re spheric refractivity can have profound ceived signal variability due to propaga effects on the performance of airborne tion over similar paths ; and 4) use the radars and other microwave systems . The measured data to determine the performance purpose of this project, sponsored by the of a simulated intervisibility measurement u. s. Naval Re search Laboratory , was to system. develop and demonstrate an airborne refrac tivity measurement system that can provide A measurement system was prepared and sent the aircraft crew with real-time graphical to Ft. Hunter Liggett, California , where and tabular output of the refractivity propagation path loss was measured over profile , and nearly real-time information several selected paths of varying lengths , on the probable effect of this profile on varying path geometries , and varying amounts the performance of their microwave systems. of vegetation and rock outcroppings . A photograph of the transmitting terminal is The system was designed to be used in the shown in Figure 3-7, on top of a telescop P-3 naval aircraft and consists of a Model ing tower which allows a height adjustment 7 microwave refractometer developed at ITS , of about 7 meters. Two frequency sources a commercial desktop computer , and a com are provided , 9.6 and 28 .8 GHz , both very prehensive computer program to control stable in frequency and power level in the the refractivity measurements . The pro outdoor environment. The tower and trans gram provides the options of displaying mitter are attached to a four-wheel-drive the refractivity , air temperature , and van , as shown , for travel into rough ter altitude data in tabular format on a rain. The receiver terminal (Figure 3-8) cathode ray tube (CRT) display , or pro is also attached to a four-wheel-drive- ducing a graph of refractivity vs . alti van and mounted on tracks to permit a ver tude on the CRT . The latter can also be tical adjustment of 6 meters . A milling reproduced on paper using the computer 's head platform is used for the base of the hardcopy feature . All of these data are terminal to permit precision travel in-line also stored on cassette tapes for subse and _ transverse to the path to be measured . quent analysis. Gain determining stages are also carefully stabilized with an overall long term stabi After the refractivity profile has been lity of the combined link of + 0.25 dB . measured , the program can produce ray trace graphs on the CRT display and , if For most of the measured paths , the propa desired , on hard copy . The ray-trace gation loss showed characteristics of a graph shows the path which a radio signal theoretical Fresnel knife-edge obstacle . would be expected to follow when trans These data were used to establish a deci mitted through a horizontally-stratified sion threshold for an idealized computer atmosphere characterized by that refracti simulated intervisibility measurement vity profile. The operator simply speci system . The simulation system showed that fies the altitude , beamwidth , and eleva correct intervisibility decisions could be tion angle of the transmitting antenna . made for 80 percent of the cases when the two end points were at least 1 meter above The profile and/or ray-trace graphs can be or below the grazing path . Whether this used to predict altitudes at which the performance level of the simulated system performance of a given microwave system · would be acceptable for an actual system may be adversely effected by the atmo depends upon its application ; however, by spheric structure . "calibrating" the terrain where the system is to operate , an optimum decision The system was flight-tested in naval air threshold can be computed which would im craft in the Mediterranean area during the prove the performance results over that summer of 1979. Preliminary evaluation of which general propagation experience would the tests indicated that the system per predict. formance equaled or exceeded the sponsor 's expectations . 105 Y·. · r.tJ·. ---- I . .• I-' 0 0'1 Figure 3-7. Photograph of measurement path from Figure 3-8 . Photogra�� o� receiving terminal . transmitter to crest (about 60 meters} . Figu re 3-9 shows examples of the path on line-of-sight digital systems (i.e. , geometry used in the measurements. The the refractive index) , a group in Division transmitter was located on one side of the 3 is presently observing the fading and obstacle and the receiver on the other delay statistics along a 22 .8 km path from side; the antennas were positioned so the Radio Building to the BAO observatory that raising (lowering ) one antenna could at Erie , Colorado . The profile of the cause the path to be just above (below) path together with the locations of the the grazing path . Path- loss measurements transmitter and receiver are shown in were made as the antenna was moved from Figure 3-15. The transmitter is shown at above grazing to below grazing. a height of about 110 m above the ground on the movable elevator on the Erie tower . Figure 3-10 shows a family of curves The profile of the terrain is drawn giving the expected diffraction gain due assuming an effective earth' s radius of to the path obstacle for four different 4/3 . This effective earth's radius is obstacle radii of curvature. important because of the relative curvature of the earth and the direction a microwave Figures 3-11 and 3-12 compare the measured beam travels . The beam is normally bent data with the theoretical diffraction gain downward a slight amount by atmospheric caused by a knife-edge ridge . refraction . The amount of bending varies with atmospheric conditions . The degree A computer-simulated intervisibility detec and direction of bending can be conve tion system wa s developed to test its per niently described by an effective earth 's formance using the measured data . Figure radius . Any change in the amount of beam 3-13 shows the performance results of the bending caused by atmospheric conditions idealized measurement system operating on can then be expressed as a change in this the measured data versus what would be effective earth's radius . This factor is expected if the propagation data had more one of the parameters under investigation signal level variability (i.e. , signal on the path shown in the figure . Also variability , a = 5 dB and a � 10 dB) . shown in the figure is the straight line Past propagation experience would have the microwave energy travels in going from predicted the signal variabil ity to be at the transmitter to the receiver . As shown least 5 to 10 dB and possibly as great as in the figure , the energy travels near the 25 dB . top of a ridge (Hoover Hill) , and this ridge also has a bearing on the propaga Results of the two measured paths are tion of energy . Since the ridge in the shown in Figure 3-14 as an example of the figure resemb les a knife-edge , the theory data recorded. The vertical axis is the of knife-edge diffraction will be used to diffraction gain adjusted so that 0 dB predict the variation in the signal as a represents the calculated free space loss function of height as the transmitter is values for the path. The horizontal axis raised and lowered on the tower. When a is labeled in feet and meters and repre portion of the radio energy strikes the sents the distance the transmitter termi top of the ridge , it can interfere with nal is above or below the crest of an the direct signal either constructively or obstacle, which in thi s case is a hill destructively , depending upon the relative along the path. Represented are two paths , phase of the ground reflected signal. In #4 and #6, which show sharply contrasting general , there is a point where the direct results . Path 6 was recorded from a path and reflected signals are in phase opposi with no prominence except the crest of tion . This first occurs when the path the hill, while path 4 had many trees from the transmitting antenna to the re surrounding the path but not in direct flection path is one half wavelength longer line . It is obvious that signal scatter than the direct signal to the receiving ing from the trees greatly influenced the antenna path . The first point of phase propagated signal. A total of nine paths addition is a point on an ellipse of re were measured , each representing a dif volution with imaginary foci at the trans ferent terrain feature . mitter and receiver , and this ellipsoid is referred to as the first Fresnel zone Propagation Model for Terrestrial Micro ellipsoid. In the figure , the lower por wave Systems�rformance predictions of tion Of the first Fresnel ellipse is drawn a digital radio system on a line-of-sight at a height of the transmitting antenna microwave path requires an accurate sta such that the ellipse just grazes the ridge . tistical model of the random parameters The effect of first Fresnel zone clearance of the channel. Because different digi is under investigation by observing the tal radio systems may have different sen fading and delay characteristics of a sitivities to the various channel impair radio signal at 9.6 or 28 .8 GBz over the ments , the model mu st be complete to the path shown in the figure . extent that it mu st be capable of dupli cating the amplitude and delay of the The work on this problem is intended to transmitted signal under all possible assemble usable and efficient information path conditions. To facilitate the under for the planning and engineering of line standing of the role of the random param Of-sight micro/millimeter wave paths for eter which has the mo st significant effect communication systems . 107 Knife Edge Ridge Smooth Round Ridge Figure 3-9. Examples of clear , well-defined paths . 108 1 0. -. � � ._. 0. :z: 1-f a: - . (..!J 1 0 :z: 0 p = 0 1-f -20 . . 1- (_j •:I 0::: -30 . u.. u.. 0.5 1-f � -40 . -4 . -2 . 0. 2. 4. HEI GHT ABOVE GRAZ ING Figure 3-10. Results for an obstacle having a radius of curvature from 0 to 1.0. :z: 1-f Theoretical Knife-edge a: 1 0. � Ridge (..!J - :z: 9.6 GHZ PI=ITH 6 0 1-f -20. 1- (_j a: a::: -30 . u.. u.. 1-f � -40. ��-� -4 . -2 . 0. 2. 4. HEI GHT ABOVE GRAZING 'Fi-ql:l:r-e- · 3-11. Normalized results for path 6, 9. 6 GHz . 109 :z t-4 (.!1-a: 10. :z 28 .8 GHZ P�TH 6 0 t-4 -20 . t- (j •:I: Ct:: -30. u.. u.. t-4 �-40. ��_.���--��--��--���_.� -4 . -2 . 0. 2. 4. HEIGHT ABOVE GRAZ ING Figure 3-12. Re sults for path 6, 28.8 GHz . 1.0 0 0.9 t/) :::::Et �---• = .:.· · 0.2 < 0.8 I ___. < E = ..... E ...... 0.7 0.3 t/) 0 0 t/) ..0 0.6 0 t/) ..0 :::::Et ..0 0:: 0 0 0. 7 ..0 ..... < 0.3 ___. 0 a.. < .... LU a.. t/) 0.8 --' < ...._ 0.1 0.9 t 0 1.0 10 8 6 4 2 0 -2 -4 -10 Distance y from Grazing , mete rs Figure 3-13. Comparison of measured alarm probability (9.6 GHz, decision thresho ld at optimum) with two theoretical alarm probabilities . 110 10. ''· r-���T-�--��--�r---��--���--�T-----� GHZ PATH GHZ PATH 9.6 6 28 .8 6 j:Q j:Q +=I ""' 3/1 9/79 10:34 t - 3/19/79 10:34 t 1 1 . e I I I I ..,/ I..,... . z . I --;'",I z .... � 1 - t a: I a: (!I (!I :z -11. z -11. 0 0 - - 1- 1- u u -21. a: -ze. ex a:: a:: t... t... t... t...... - -�_;�.;:} ""' � -38. . • -te. -e. -6. -4. -z. e. z. • '· •· -a. -6. -<4. -2. . 2. 4. . . · HEIGHT ABOVE GRAZING (rTl . . HEIGHT ABOVE GRAZING (rTl • ��---�------�------��------7r· -- . , -3. -z. -1. e. 1. 2. -� -2 . -� . -7. , . 2 . HE IGHT ABOVE GRAZING (Ml HE IGHT ABOVE GRAZ ING (Ml 1-' 1-' ------1-' '"· r-� �GHZ� PATH�--� -r ---r-----r-----T-----T---r� IO. r--r-----r-----r-----r-----r-----r-----r----�----�-----, 9.6 4 GHZ PATH 28 .8 4 ""';:q 3/15/79 17 :45 & 18:06 j:Q ""' 3/15/79 17:45 & 18 :06 e . • .,..""'� I I � ,..,..; z..... I I I I V z..... � 1�-r��..fik ¥?:· a: � a: "1 (!I fo.' . (!I • ' J.i/iJ:lit . . . -18 • • f'�{M. · 'f•\ . · ;.;�'I· z -u., -� ' -• �... · \·. �� .t;� ��i -�'�h �I1 z w' .....0 · · 0 l� �l.f:' '1- ;t�.. t ;! � 1- , u �·:;i : a: -2• • a:: r t... a:: �t... t...... t... - .... ""' 38. ��- t�e�. ��-�. �. �----�•--��-. �.-.--��-�z .�--�L. .--��.�. �--�. �.--��7. .---- 0• � ...... �� ...... · ""' - ... c...... �- -.z. .L....t. z. 4. t.. •· HEIGHT ABOVE GRAZING (FTl -us. -a. -6.--�-��� -4...... -��- HEIGHT ABOVE GRAZIN�G (rTl -�..J --L---- I -3. -2. -1 . •• 1. 2. HEIGHT ABOVE GRAZING tMl -2. -1. •· l- a. HEIGHT ABOVE GRAZING (") figure 3-l4 . pi;llfract:j:,on reault;; . 1800-----.----.,------,------ en .... Q) - Q) E - ..c:.. C' Q) :I: 0 22.8 km Radio Bldg Kilometers Erie 112 3.2.2. Ionospheric Characteristics not have exceeded 30 MHz for the same paths and Effects traveling via the unmodified ionosphere. Because there is little known about how High Frequency Ionospheric Scattering the characteristics of propagation modes �· Efforts to recover high-frequency that are presumed trapped by ionospheric (HF) radio signals trapped between layers gradients such as the RTW , it was - specu of ionization which surround the earth at lated that an artificial reflector pro heights of 150 to 250 km have been success duced by the Platteville high-powered ful . This work (performed under the spon transmitter would test the argument that sorship of the Rome Air Development Center ionospheric trapped modes do exist. located at Hanscom AFB , Massachusetts ) is directed toward determining if there are Re ceiving sites to test this speculation low- loss trapped propagation modes which were located at Alamosa, Colorado , and could extend the useful range of surveil Los Alamos , New Mexico , about 250 km and lance systems well beyond the normal over 500 km south of Platteville·, respectively . the-horizon distances (-2000 miles). It An eight-e lement beverage antenna array is well known that, for periods of time was cons tructed at both sites and aimed near local sunrise or sunset, HF signals towards the region in the ionosphere where can be transmitted into the nighttime part the scattering volume produced by the of the day/night terminator and that the Platteville transmitter would occur . SRI , same signal can be detected arriving from International , also under contract with the day side of the terminator, after the Rome Air Development Center , installed traveling around the world , approximately a swept-frequency FM/CW transmitter and 135 ms later . A delay of this magnitude log periodic antenna at Salisbury , is appropriate for the propagation time Australia, 14 , 500 km from Platteville. required to circle the earth at a height The FM/CW transmitter was programmed to within the ionosphere. Evidence indicates sweep in frequency from 12 to 30 MHz at a that , when the transmitter and r�ceiver 100 kHz/second rate . During the first are located at the day/night terminator , experiment conducted in the last week in ionospheric layer gradients and irregular April of th is year , significant results ities in electron density can result in were obtained to show that trapped modes the launching of a propagation mode which could be recovered from the ionosphere. can be guided by ionospheric boundary The tests took place between 0700 and 0900 gradients , much like a waveguide, around UT (_0000 to 0200 MST) . The highest fre the world (RTW) • The same mechanisms quency propagated by conventional multi-hop (i.e. , geometry of ionospheric gradients modes was about 23 MHz. When the Platte and irregularities ) can also result in ville transmitter was turned on with the the ability to recover a (RTW) signal from modifier , signals were detected up to the ionospheric heights . This mechanism for limit of the frequency range employed (30 launching and recovery is likely to reduce MH z)_ . The signal level of the trapped the signal level for each transition by modes exceeded by 10 dB or more that of several tens of dB . It is believed that , the mul'ti-hop mode measured at the same once launched , the propagation loss is frequency . Computer simulation employing comparatively small. realistic ionospheric structures was used · to verify that the extended frequency sig Experiments using a very-high-powered HF nal recorded was an ionospherically trapped transmitter to excite the electrons in ( not .reflecting from the earth's surface) the ionosphere and create a scattering mode of propagation. volume were conducted from 1970 to 1974 (Radio Science , November 1974) . The A second experiment was conducted on the artificially created scatterers are com 5th of June with substantially the same posed of numerous very elongated bubbles results between 0620 to 0820 UT . Obser of increased electron density with their vations were made at other times of day longitudal axis aligned along the earth' s without success, presumably because of the magnetic field lines. These bubbles in inability to launch an elevated mode except the ionosphere approximate slender cylin at local sunset , which does correlate with ders and are aligned along the earth' s the times above . magnetic field because the flow of charged particles transverse to the field lines As the data processing progresses , more are greatly impeded . wi ll become known about signal losses and height of reflections from the transmitter The NTIA/ITS high-powered transmitter induced artificial scatterers . A test facility located near Platteville, Colorado , series is planned under Air Force sponsor can produce about 1.6 megawatts of average ship with a transmitter aboard the space power , which is used to excite a 10 ele shuttle and located at ducting heights in ment ring-array antenna. Observations the ionosphere . made prior to 1974 showed that the field aligned scatterers acted like a large F igure 3-16 shows a processed ionogram of reflector of radio signals at ionospheric the Salisbury FM/CW transmitter as received heights for frequencies in excess of 400 at Alamosa , Colorado , on 5 June 1979 . The MHz. Regular propagation modes would ionogram starts at 12 MHz on the left and 113 JUliAtt DAYt 156 JIH£1 7t !51 9 JULIAN DAY: 156 ••• df'lo 1111H e.t- s�m. df'l•,. offs•t t.u)azeee "'"-rte.�� 7., STM.o dchv oHut(I'IS)I2908 Kln-n. .. dfl4 (f'l$11 e.o- 7.� St•rt-S\o� ot s.ou� fn,,(��UIZ.0-39.8 Stort•Stot> e.\ '"'•"' fr•,·<"Hz.>�t2.8-38,e T'"'' foc.\01"1 1.99 Ubl"IHOUJ Ronu .JUlJAH DftVt I� .., � n.c. d•lo �.� 5Yne. cMlav otf u•t •,.,tU21)00 Hu•-no dcl•r "' 1 oHs" ,.,uzeae t11r-tt4 J�oh. ,,.,u t\.il SU�l·S\� G\ SWf'.P fr.,. (rtH�• :Jl. B�J-8.8 $.\ort -Sto.> u '"''•' •nu . "": •tt�.0-?0.8 Tu•• fe.c.tort 1.ee Uba"'uHou• IGC.\Orl . I 490Hz. �onti' IHz.>' z-ooe lll'lf 1.80 Ubllhl\1.)<..11 F-"-11 Figure 3-16 . Examples of ionograms for the Salisbury , Australia , to Alamosa, Colorado , path with (right side) and without (left side ) the artificial ionospheric scatterer . 114 increases linearily to 30 MHz . Signal of the transmission media are incorporated delay is preset to 48 milliseconds (ms ) into engineering models . These models are and the scale of 0 to 7 ms (bottom to top being developed for users within and out of ionogram) adds to obtain the overall side government. As in Section 3.2, we path delay . The ionogram on the left first discuss the non-ionized media cases , (0645 and 0705 UT ) was recorded with the and then those primarily influenced by the Platteville transmitter "off" and no arti ionosphere. ficial scatter present in the ionosphere , and the ionograms at the right were taken 3.3.1. Atmospheric Transmission Models with the Platteville transmitter "on" and the scatter present. It is quite apparent Atmospheric Transmission Models . This totally new rays appeared at about 5 ms program is a continuation of the effort delay extending in frequency from about to create and maintain an information 18 to 28 MHz. The darkness of the iono system of computer propagation models and gram is portional to the received signal data bases . These models and data bases level, and it seems likely that a small represent a consolidation of the results contribution from the artificial scatter in telecommunications research to be appears on the first ray , which is the accessible nationwide to support the de 4-hop signal between earth and ionosphere sign and evaluation of telecommunications enroute from Australia to Alamosa. The systems . Two Reports have been published delay analysis of the elevated mode signal thus far . The first is entitled "A is quite complex and ray paths must be Preliminary Catalog of Programs and Data mapped to evaluate these delays, but it is for 10 - 100 GHz Radio System Predictions" obvious that the scattered signals travel and is OT Report 78-141 . The second is an extra distance of about 500 km , twice entitled "An Ad ditional Catalog of Programs the distance from Alamosa to Platteville , and Data £or 100 MHz to 100 GHz Radio further than a signal which is not re System Predictions " and is NTIA Report flected from the scatter . 79-15. Tops ide HF Noise. In order to assess the Computer programs and data bases under HF environment in the topside ionosphere , the following categories now exist in the ITS has investigated the data observed by catalogs . the Defense Meteorological Satellite . This satellite is equipped with an HF Category Title radio receiver that provides measurements of the inten sity of HF noise at the satel 1. Computations of Transmission lite orbit (almost circular at 840 km) . Loss and Radio Returned Power The data have been analyzed according to local time and location on the globe . 2. Computations of Desired/ Undesired Signal Global maps of the intensity of the HF noise in the topside ionosp here have been 3. Computations of Atmo spheric produced for various frequencies between and Precipi tation Parameters 4 and 13 .5 MHz . An example of one such map is shown in Figure 3-17 . The map pro 4 . Data Bases and Associated vides contours of the receiver terminal Programs voltage as observed by the satellite over a three-month period from September through 5. Performance of Digital Communi November 1977, for the frequency of 12.0 cation Systems MH z. By producing and analyzing maps such as these, it has been found that the data 6. Miscellaneous Programs observed by the satell ite appear to ema nate from discrete trans missions at the Additional entries to the information surface of the earth . Further study has system are being solicited and evaluated revealed that the HF environment in the on a systematic basis , and a new catalog topside ionosphere is in concert with the is anticipated to keep those interested manner in which the HF spectrum is utilized abreast of this valuable information . for terrestrial point-to-point or point to-area services . The mo st intense sig Multipath Fading on Long 15 GHz Paths . nals in the topside ionosphere are ob This project is designed to acquire data , served in those bands ass igned to the analyze it , and develop empirical para broadcasting service , followed by those metric relationships for des igning long assigned to the fixed , maritime mobile , (greater than 50 km) line-of-sight micro and aeronautical mobile services , respec wave links . The largest part of the data tively . base for models now being used was obtain ed on short pa ths , for relatively short SECTION 3.3. DEVELOPMENT AND periods , and at frequencies between 4 and IMPLEMENTAT ION OF EM WAVE 6 GH z. Although there is some data at 11 TRANSMISSION MODELS and 15 GHz , much of these data were ob tained using recording techniques which Information about EM Wave Transmission did not provide adequate time resolution Characteristics and the characteristics for obtaining short term statistics. llS t-' t-' "' 12.0 MHz, DAW N Figure 3-17. Average global behavior in the topside ionosph_ere of the RF rad,io environment at local dawn fo1: 12 MHz during the period September-November 1977 . Contours· are given in millivolts x 10-1 2880K. Data acquired on this project are being important that we know what these meteor obtained using carrier frequencies near ological parameters are doing on a daily 15 GHz. The data are acquired on three basis . The daily information is neces long paths (90 km, 93 km, and 132 km) sary for helping to identify radio propa which converge at Mt . Corna, Italy (see gation mechanisims and also to compare Figure 3-18) . The 93 km path is primarily models on the basis of the statistics for over water . The data acquisition period the year of the testing . Daily reports will be one year beginning April 1979. of meteorological data are being obtained Recording of data will be done using digi from the u. S. Air Force Environmental tal magnetic tape after the data are first Technical Applications Center (MAC) , Scott preprocessed by . computer in one hour blocks . Air Force Base, Illinois . The data will also be recorded on strip chart to aid in categorizing fading mech The USAF organizations sponsoring this anisms . This categorization is done in project are the Air Force Communications an attempt to separate signal level varia Service , Scott Air Force Base, Illinois tions into incidence of Rayleigh fading , and Headquarter Electronic Systems Divi rain attenuation , other forms of power sion , Hanscom Air Force Base , Massachusetts . fading , and equipment malfunction . To be comparable with prediction methods now in Pr·opagation Measurements Guidelines. use , the data will be analyzed to predict Sponsored by the Communications R&D Com Rayleigh fading incidence occurring during mand (CORADCOM) of the Army , this project the worst 30-day period. was originally planned to provide general ized guidelines for designing measurement The project is sponsored by the u. s. programs where the maj or purpose is to Army Communication Command in response to examine some aspect of radio propagation . increased pressure to change military But it soon became apparent that a more radio systems to operate in the 15-GHz immediate concern had to do with the very band within areas of high microwave spec special problem of wide-band propagation trum usage . through forests. In response, we have fashioned guidelines and suggested possi Fa�ing Lon 7 - 8 GHz . a modest number of field measurements in south-central Tennessee. The principal Received signal levels will be monitored tool to be used is the pseudo-noise probe at 8 GHz on five links (Figure 3-18) . owned by ITS. It has a bandwidth of 300 The three links terminating at Mt . Corna MHz and provides an effective impulse sig wi ll be monitored on both 8 and 15 GHz nal of about 6. 7 ns resolution . It will for one year . The two links terminating be operated with center frequencies at wi ll be monitored at 8 GHz for one year . 600, 1200, and 1800 MH z. The transmitter Recording and processing of data will be is to be mobile and the receiver semi done using the same techniques used for mobile . We plan to record the data in a the 15 GHz project. digital format which can be made available to interested parties . Even in this first The type of meteorological parameters phase we hope to be able to address and that are used in the prediction models answer some outstanding questions concern are ones that are readily available from ing multi-path and pulse spread when pro past meteorological records. For example , pagation is through forests or near stands average annual temperature is used in of trees . the multipath and atmospheric absorption models . Average annual absolute humidity Wide"'Band Radio· Propaga· tion Measurements . and air pressure are used in the atmo Th�s proJect has developed a computer con spheric absorption models . The rain trolled system for digitally recording the attenuation model uses average annual output from the ITS psuedo-random channel rainfall , the ratio of thunderstorm to probe . The digiti zed output from the probe stratiform rain and the average number wi ll be analyzed on a large computer to of thunderstorm days per year . determine the wide-band characteristics of propagation in the 400 to 2000 MHz fre To compare these prediction models with quency range . the data from this experiment , it is 117 Mt. Paganella Mt. Corna 4 Venda 15. 0336 iiH;t. N :z: E c.::l � C) en ca • (.Q � � • (¥) ~ Ln .... � Mt. Cimone Figure 3-18 . Path locations for the long path 15 GHz multipath fading tests . 118 This digitizing system is controlled by a tics are available and may be used to commercially available 8-bit microprocessor anticipate the performance of HF communi system as shown in Figu re 3-19 . The six cation circuits and thereby provide the outputs from the receivers are digitized lead time for necessary equipment selec and stored in buffers at a rate determined tion , frequency selection , and frequency by the operator . The receiving antenna and time-sharing arrangements . height is measured with the electronic distance meter , and recorded along with The IONCAP program or calculations using the propagation data . These data are the program are available from the Propa then written on digital tape for later gation Predictions and Model Development analysis . The software has been designed Group of the Applied Electromagnetic to be flexible and yet easy to use . The Science Division of ITS . The program has operator communicates to the system through been supplied to several foreign and domes the printing terminal, which asks for his tic government agencies and to the private input . A sample of the questions and sector . answers is shown in Figure 3-20. A pro vision was made to store all of the Development and Improvement of Prediction housekeeping information on a header re Formats . The ICA/VOA , in maintaining and cord at the beginning and end of each file improving its worldwide broadcast schedules of data so that the system is self docu on high frequencies , requires predictions menting of the measurements that have been of its expected broadcast coverage well in recorded . A sample of the information in advance to prepare for its broadcast sched the header , data , and trailer records is ules . predictions have been delivered on shown in Figure 3-21. schedule , and VOA continues to make occa sional use of their programs by remote 3. 3. 2. Ionospheric Transmiss ion Models access. Work has been done and will con tinue to adapt the new HF predictions pro Computer programs developed by ITS for gram (IONCAP ) to VOA' s needs . IONCAP out predicting ionospheric transmission and put wi ll be compared with HFMUFES (the the performance of HF radio systems are present program) output , and both will be used by government agencies and commercial checked (by VOA) against monitoring re firms in the U. s. and other nations . A sults . continuous program is carried on to up grade and expand predictions services to HF Sharing and Power Studies . .A.nother fit users ' needs . example of the use of EM ionospheric trans mission models is the work for NTIA and Normal day-to-day and hour-to-hour depar FCC in development of technical material tures of critical frequencies (foF2) and to support the u. S. position at the 1979 other ionospheric characteristics from ob W.A.RC . The use of these models to support served median values have a significant the u. S. position was provided in a effect upon the range of useful frequen technical report "Theoretical Compatibility cies on HF communication circuits . Even Between High Frequency Broadcasting and greater effects result from disturbances High Frequency Fixed Services" which is in the earth 's magnetic field and from currently in editorial review . certain forms of activity on the sun. Th is report considers the propagation The Ionospheric Communications Analysis aspects of frequency sharing especially Predlction Program (IONCAP ) is the most as related to the short and medium dis re cent of the HF prediction programs tance , lower power operations of the fixed developed at the Institute for Telecommuni service as compared to high-power interna cation Sciences (ITS ) . The computer pro tional broadcast. published international gram is an integrated system of subrou high- frequency broadcast schedules as tines designed to predict high-frequency directed toward selected areas were com (HF) skywave system performance and pared to the expected times of successful analyze ionospheric parameters . These low-power operations within those areas computer-aided predictions may be used in and comparisons were made of the relative the planning and operation of high fre signal strengths expected from the high quency communication systems using sky power transmitters relative to the ex waves . pected signal strength of the low-power operations . These comparisons were made In the initial planning or in the modifi wi th recently improved skywave field cation of many communication systems there strength prediction methods developed at may be an appreciable delay between the the Insti tute for Telecommunication circuit planning and the actual circuit Sciences , and field strengths as predicted construction or modification . This is of by these methods were compared with ob particular importance for high frequency served fields on short and long distance (HF) circuits which have marked time and circuits . geographic variations in optimum frequency , required power, and system performance . It was concluded that appreciable oppor tunity for frequency sharing exists , and Predictions of ionospheric characteristics examples were shown as to how this oppor and techniques for using these characteris- tunity may be predicted and used in the 119 CALENDAR CLOCK l r RECEIVER NO . 1 4--y � � - AGC ANALOG TO � DIGITAL Vt MICROPROCESSOR X DIGITAL TAPE RECEIVER CONTROLLER v CONVERTOR RECORDER NO . 2 y- N AGC .11I' '"" "" TRIGGER t-' N PULSE INP [JT 0 I'1/ ELECTRONIC l DISTANCE PRINTING METER TERMINAL Figure 3-19. A b1ock diagram of the data record�ng system used in th� wide-band mea�urements . ••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••• WIDEBRND PROP8GAT ID� MERSUPEMENT SYSTEM . ••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••• DATE : 8./;?7./79 T Tto1E : liS:2 0: .:: ,::. f"'·Oto ·? Nl '..-' IJU I,IRNT TC1 RESET THE CLOCK ·;· N \) FNTFP lPCRT JnN C<= 20 CHP�) : ?BOULDER 2> FNTFP PATH TD <<= 20 CHPS) : ?TEST :,) fNTFR FPF(.II.IFNCY {MH7) FOJ;:< PE(:fI '·i f.I<' 1: ·<".4 0 0. 0 8) ENTER FRFOWENCY CMH7> FDP PECE IVER 2: 7800 4; ENT ER Nl.lt{f!ER [IF FPF1�1fS· TO AVERFIGE q -1 0) : ·;- 1 0 5> ENT�R NUMBER OF FRAMES OF �ATA TO BE RECORDED Cl0-4500) : 7100 6) ENTER FRAME RATE C1,2•5· 10/SEC> : 71 0 7> ENTER SAMPLE RATE <1 0-1 0000/SEC) : ?1 0000 S) FNTEP NUMB�P. 0� SAMPLES/FRAME C1 0-1 000> : 71 000 OF S:I1PLE S: ETS 0(1) : "" 0 10":o FI'ITFR CQMMFNTS Cl LINE) : ?TEST fl(l YnU I,I T�H TO i.: HRNGE At�Y FtNS:I,IfF.'S 0::\'/m ? ·7· 'r' FNTFR ���T TnN N(1 . nR CP WHEN DONE : 73 "::l) ENTFF· FRFOI. IFNI.:Y CMH7> Fnl'· REC:EI VER 1 : ?6 0 0 :?.) FNTF.R FRFf.H.. IFNCY CMH:?) F[1P r;:• fCF I VEl<' 2: ? !;'� 0 0 . . EtHFP (• I.IF:'=:TT[l� NO . [1R I":R I.IHHl DONE : , l.o lf:PMS HERTlER I �!PUT DATA S:UMto1AP\' : . I!FtTF.: 8 . •27...-?9 Tl ME: 16: 24 : 1 8 n t n.-:RT Tnt� : FOUl r• F.R A 2> P TH JD: TE�T · f) JE 1 ·:: ) FRE I. NCY (MH?":o l=nR F'ECEI VER : 6 0 n. FRJ:="OI.'FNI":',' CMH?) FtlR F' ECE J VEP c' : 1 c: 0 0. N1. 1t-1l Figure 3-20. A sample of the questions and answers . 121 WIDEBAND PROPAGAT ION MEASUREMENT SYSTEM DATA ACQU ISIT ION RECORD DESCR IPTION Header Record Date Time Location Path ID Frequency for receivers l and 2 Number of frame s of data to be averaged Number of frame s to be recorded to tape Frame rate/sec Samp le rate/sec Number of sample sets to be taken/fram Number of frame s to ship between sampled frame s Comments Data Record Up to 1000 12-bit A/D sample sets (X & Y components for receivers l and 2) AGC A/D samples for rece ivers l and 2 Distance me ter reading Date Time Trailer Record Flag to indicate if preceding me asurement set is good or not Up to 10 lines of comments de scribing any unusual conditions occurring during the preceding me asurement set Figure 3-21. A sample of the information in the header , data , and trailer records . 122 development of operational schedules so spheric data to be incorporated into them that the fixed and broadcast services may and will be used in propagation simulation take advantage of time sharing or geo programs to reproduce the actual radar graphic sharing (simultaneous co-channel characteristics. The ionospheric absorp use) of frequencies in the high-frequency tion suffered by the radar signals and the band . impact of irregularities in electron den sity will also be modeled and compared Figu re 3-22 is a sample chart illustrating against actual radar data . how EM ionospheric transmission models may be used to develop geographic area sharing In addition to modeling , the polar iono plans for high frequency services . spheric structure and other parameters of importance to the performance of an HF Another use of skywave field strength pre backscatter radar , the ITS will be devel dictions to support U. S. WARC positions oping optimum methods to store and retrieve was in the area of deducing the optimum the polar ionospheric data . The types of power for international broadcast trans data and the locations at which they will mitters to maintain a given quality of be observed are given in Figure 3-24. service. The results of this study show that , under mo st circumstances , coverage VHF/UHF Measurements in Urban Areas . The by the broadcast can be effected at dis objective of this program is to provide tances less than 5000 km by using powers measurements of the signal strengths of less than 100 kW . VHF/UHF broadcasts in an urban area which can be used as a basis for implementing Prediction of Transmissions Parameters and improved techniques for predicting the Sys tem Performance. Models for EM trans= coverage of UHF-TV and mobile radio mission via the ionospheric mode of propa systems . During this year , a measurement gation were used to conduct feasibility program was designed and carried out for studies for new applications for high gathering data on the statistical variabi frequencies in the long range planning of lity of signals from existing transmitters Federal agencies . The use of these models in the VHF/UHF band in the Denver metro to assist the Department of Transportation politan area. in the updating of their aeronautical communication systems was provided in a Measurements were made using the TV trans technical report "Theoretical Feasibility mitters located on top of Lookout Moun of Digital Communication over Ocean Areas tain near Golden , Colorado . The signals by High Frequency Radio" NTIA TM 79-17 . monitored were KBTV (189 MHz) , KMGH (177 This report examines the theoretical reli MHz) , KOA (69 MHz) , and KWGN (57 MHz) . ability of digital data transmi ssion via Mobile measurements of these signals were high-frequency radio for typical air made at several vehicle speeds along 44th traffic routes in the Atlantic and Pacific Avenue in Golden , Colorado . The antenna areas in an evaluation of a system for used was a modified version of a miniature improving air traffic control over ocean VHF directional antenna system originally areas . The expected performance of a designed to provide continous coverage of reference high-frequency data transmission the 30-200 MHz frequency range . The system of 1200 bits per second with a modified antenna was converted to an iso permissible error rate of one-in-a-thousand tropic antenna using a hybrid network with binary error was expressed as a percentage a 20° phase shift. The receiver system of time that a given theoretical reliabi wa s installed in a mobile van . lity will be equaled or exceeded. Typical received s ignal variations of Transmission models permitted the deter Channel 9 (KBTV) at 187 .24 MHz (video ) and mination of optimum high frequency for 191.74 MHz (audio) measured at a mobile digital communication from aircraft and speed of 20 mph are displayed in Figure also the optimum ground locations for 3-25. These measurements were obtained reception . These bands and ground loca over a test course of approximately .7 tions were found to vary with aircraft mile (1200 meters) , which simulated the location and time of day . Figure 3-23 is urban environment of large steel and con an example of the determination of these crete buildings . The correlation coeffi optimum bands and receiver sites . cient was less than 0.5 for the multipath scattering on the video and audio signals. Polar Ionospheric Propagation . As part of �nspection of Figu re 3-25 suggests that the program to assess the performance o f the fading mechanism may be similar to the CONUS over-the-horizon backscatter that invo lved in tropospheric scatter , radar system, the Air Force Geophysics Lab i.e. , a random mu ltipath effect. It can oratory and the Electronic Systems Division be shown that this type of transmission are supporting a development effort at ITS produces a received signal whose cumulative to assist in this assessment . The ITS is distribution function (CDF ) is a Rayleigh developing optimum models of the polar distribution . The data in Figure 3-25 was ionospheric electron density that represent analyzed and processed to obtain the CDF's, the structure of the ionosphere during the and the results are plotted in Figure 3-26 time periods that the radar will be oper on Rayleigh Distribution Function paper. ating . The models wi ll permit actual iono- On this coordinate scale , a Rayleigh 123 Rabat, Morocco 158.73° BROADCA ST TRANSM ITTER BEAlONGIO RCVR OPTIMUM AERONAUTICAL BAND FOR C�ICATION OM THE SAN FRANC ISCO Lagos , tligeria 342.38° HONOLULU ROUTE DECEMBER - HIGH SOLAR ACTTVITY FIXE])CI RCUIT RECEIVER BEARING TO RCVR SAN FRA!!CISCO HO!IOLULU March 70. 9.6 l'll z lllNTH SOUR ACTIVliY FREQUENCY 00 t J 7 7 7 I I I -60 Y I ...... AVAILABLEsfGtiAl _- • I 11.3 -30 co -100 - f ;, ::.:0 REQUIRED SIGNAL \ r IN PRESENCE OF I 250 kw REFERENCE NOISE SSB VOICE BC CIRCUIT ""Lo.J 0 \ I >- ::.: 50 dB ::E >-"- -120 I � r /. \ REQUIRED SIGNAL IN "' \ z " PRESENCE OF N...... -"- INTERFERENCE UJ "" ""> Lo.J \ '-'UJ -140 "" \ .._ I ------'NOISE DENSITY -160 . I li lt I ItI \I 00 -- . --- • ------I I I \ I ------· 0 - -1ao L______-::---;�----:�-- 00 ..L_04 _L08 12 16 20 �00 OJSTAMCE FROM SAN FRANCISCO - � UT e Figure 3-22 . Chart to estimate time of compatiple Fisure 3-23 . S�le graph which could b used to assist operation between the fixed service and �n. the select:j:on o� a theoretically o timum ae�onautical channel. a broadcast tran.smitte.r operating. p at 9.6 MHZ . AFG� IONOSONDE OT BACKSCATTER e MAGNETOMETER :;d·� GEOPHYSICAL STATIONS FOR ERS TESTS A RIOMETER Figure 3-24 . Coverage area of the CONUS OTH-B radar system . I �ffiz RECEIVED SIGNAL VARIATIONS AT 187 .24 �ffiz (V DEO) A:-JD 191 .74 (AUDIO) AT A HOBILE SPEED OF 20 HPH EAST ON 44TH ST. IN GOLDEN COLORADO: TRANS�UTTER KBTV , 6 JUNE, 1979 N ------748 HAVELE GTHS 8 "' '0 z H -1 ,_, 00�------"' > -----� "' ,_, :;;j 76 7 I -lOO ------__ ·�------·-�------� ----�------··-··� - !.- -·------I �---I-----�0--1m_ N 0 T HE S EC S 134 0 RELATIVE DISTANCE IN �1ET ERS 1200 Figure 3-25. Typical received audio and video signal variations of Channel 9 (KBTV) measured at a mobile speed of 20 mph between 2.5 and 3.5 miles from the transmitter in Golden , Colorado . 1.25 RUN NO . 15 EAST ON 44TH ST. AT 20 MPH 6 JUNE, 1979 CUMULATIVE PROBABILITY DISTRIBUTIONS FOR 187 .24 MHz (VIDEO) AND 191.74 MHz (AUDIO) RAYLEIGH DISTRIBUTION FUNCTION SCALE - 30 -- \ 1\ I - 40 '· ---- ', �, ' .... 1\..... ' , s ><=� ' "<:I , - 5 0 \1 I z i\' H � \ 0 :::> E-1 �, H ....1 � :> H � ' -60 " " tJ....1 � ' �' ,� \ \. ' - � 70 �, . - 80 .01 1 10 30 50 70 90 95 98 99 % OF DATA EXCEEDING THE ORDINATE Figure 3-26. Cumulative probability distributions for the Channel 9 (KBTV) signal on a Rayleigh scale . 126 distribution would plot as a straight comparison. In addition, maps of "broad line, and one can see that the observed cast coverage" for representative VOA CDF 's are very nearly "Rayleigh. " For transmi tter sites have been prepared as an purposes of comparison, the same CDF's alternative output for study by VOA per were plotted on so-called "Gaussian" paper sonnel . (Figure 3-27) . On the se coordinates , if the distribution were a Gaussian (or normal) CDC 6600 files have been maintained for probability function , the CDF's would also local batch processing and , under the VOA plot as a straight line . It would appear Time Share Service , they are available-- that the observed distribution is more for use by means of access from a remote nearly "Rayleigh " than "normal." However , TELEX terminal. Files are also maintained additional analysis of all the data will on the XDS 940 for interactive time-share be necessary to verify this rather tenta access by VOA to the prediction program . tive conclusion . In addition to VOA , there are other govern Ionospheric Mapping Study . Numerical ment agencies and industrial organizations models of median ionospheric character requiring Numerical Prediction Services . istics have been developed by ITS and are This project provides HF radio propagation widely used for predicting radio wave predictions and computer programs on a propagation either via the ionosphere or cost reimbursable basis . through the ionosphere. HF radio propagation predictions were pro The models for the F2-layer critical fre vided routinely to ITT World Communications , quencies, foF2 , and the transmission Associated Press , NOAA/SEL , and the Ameri factor for a 3,000 km path , M(3000)F2, can Radio Re lay League (for publication were derived from observations made in (QST) . lTS made predictions for Gulf between 1954 and 1958 . A study for the Oil Communications , Radio Netherlands , Department of Defense is underway to McPhee Consultants , Sabre Communications , determine if there are any systematic Scientific Radio Systems , USDA Forest differences with either solar cycle acti Service , Atlantic Re search Corporation, vity or season , between the predictions Barry Research Communications , Page Iberica , and observations for the years of 1968, TRT Telecommunications , Federal Electric 1970, 1972 , and 1974 . Based on these Corporation (Vandenberg AFB) , and Adventist results , ITS will develop a program to World Radio. Radio Netherlands is now improve the numerical maps in those areas engineering a new broadcast operation at of the world where substantial improvement Hilversum, Holland , and has requested is indicated . Theoretical numerical extensive predictions for th is site . ITS techniques , as well as other sources of has received two requests for atmospheric additional measurements , (e.g. , satellites) noise data "numerical maps" which have will be considered . been filled according to detailed instruc tions from those requesting them: RD SECTION 3.4. PREDICTION OF TRANSMISSION �ssociates , and CNET in Lannion , France . PARAMETERS AND SYSTEM PERFORMANCE In addition, predictions were sent to the following companies in support of HF sys Completed engineering models for EM wave tems design and were supplied to foreign transmission calculations are delivered governments , especially in the Middl� Easti to sponsoring and requesting agencies for BR Communications , Canadian Marconi , CCA their use. Following are representative Electronics , DHV Incorporated , Sabre Com u�es of these services . munications , Scientific Radio Systems , Singer Products Inc. , TAI , Techno Gener 3.4.1. Long-Term Ionospheric Predictions Ltd . (Irah)_ . �TC in Denver needed pre dictions for the projected reception (for The ICA/VOA requires regular predictions midwest rebroadcasting via cable) of VOA of "circuit" performance as an aid in plan programs from the east coast of the United ning appropriately for the continuation of States . Also under the reimbursable Num its world-wide HF broadcasts . erical Predictions Services project, pro gram tapes were sold to Granger As sociates , The Radio Propaga tion Predictions project Hoyles Niblock International Ltd , Merle provides the VOA every second month with Collins Foundation , Shape Technical Center , HF circuit performance predictions for National Institute for Telecommunication about 180 broadcast circuits 8 months in Research (South Africa) , United Marine advance . For about 150 of these circuits Electronics A/S (Norway ) , and Johns Hopkins (from Tinang , Kavala , Greenville, Woofer APL . The program was provided without ton, Monrovia , Munich, and Tangier) , the cost to the Radio Re search Laboratories predictions include selection of optimum in Tokyo . transmitting antenna. In the past, the predictions program , HFMUFES , has been Saudi Arabia HF Predictions . The Propa used . With the development of IONCAP , how gation PredictTon andModel Development ever , HFMUFES will gradually be replaced . Group of ITS has undertaken a project to For the VOA , a set of predictions made develop high-frequency (HF) radio propa with both programs have been submitted for gation predictions for the Kingdom of 127 RUN NO . EAST ON ST. AT MPH '6 JUNE , 15 44TH 20 1979 CUMULAT IVE PROBAB IL ITY DISTRIBUTIONS FOR (VIDEO) 187 .24 MHz AND (AUDIO) GAUSSIMN DISTRIBUTION FUNCTION SCALE 191. 74 MHz - 30 � K - 40 �, ' ...... AUDI O' ..._ ,� ...... I'! � ' '"0 -50 z 1-\l\ H r''\ � :;:J H "� H ....:l \� � �r.::l � :> H fir.. - 60 �� j� � � '\\ \ \ - 7 0 '" ,'�, - 80 1 10 30 50 70 90 99 % OF DATA EXCEEDING THE ORDINAT.E Figure 3-27. Cumulative probability distributions for the Channel 9 (KBTV) signal on a Gaussian scale . 128 Saudi Arabia as an aid in broadcast sched HF/UHF Propagation Evaluation . The Insti uling . These predictions were intended tute for Telecommunication Sciences has to assist the Minister of Information in been involved in an HF/VHF propagation Saudi Arabia to more effectively determine valuation program for representation of an optimum assignment of frequency for the United States intelligence community their broadcast circuits. to enhance their operational capabilities . This included tasks to supply technical A total of seventy-nine worldwide receiving consultation on HF/VHF propagation-related sites were specified by the Director of problems and provide comparison of observed Frequency Management of Sa udi Arabia with and predicted HF propagation parameters . the transmitter location at Riyadh , Saudi This included numerical simulation of long Arabia. Four antenna ty pes with appro distance high-frequency radio propagation priate bearings were reque� ted f�r a total system performance and HF per formance pre of thirty-one antenna conflguratlons (see dictions utilizing the Ionospheric Commu Table 3-1) . nications Analysis and Prediction Program (IONCAP ) de veloped at ITS . Table 3-1. Transmitter Antenna Configurations The IONCAP program wa s used to predict specific circuit parameters. These pre dictions were then compared against obser Number of Type vations of HF field strength , maximum Bearings usable frequencies , and lowe st observable frequencies . The source of observed data Curtain Antenna (one band) 14 wa s primarily CCIR documents . Particular emphasis was placed on the extension of Curtain Antenna (two band) 14 the IONCAP program to frequencies from 3055 MHz . As part of this task , it wa s Fixed Log Periodic 2 necessary to develop specific antenna model routines for antenna designs speci Ratable Log Periodic 1* fied by the sponsor . *Ratable to main beam. 3.4.2. Medium Frequencies Transmission Studies The predictions were prepared using the Ionospheric Communications �nalysis and Band Coverage Prediction Techniques. Prediction Program (IONCAP ) developed at AM Propagation by skywaves in the medium IT S and constituted a significant utiliza frequency (MF) portion of the spectrum tion of the flexability and optimization significantly impacts the performance of of IONCAP . Both tabu lar and graphical broadcasting service , especially at presentations of the various prediction AM night . Standards of performance and parameters were presented that included quality of service during nighttime hours graphs of the expected diurnal variati n � are determined using methods to deduce of Maximum Useful Frequency (MUF ) , Optlmum field strengths due to MF skywaves that Traffic Frequency (FOT ) , and Lowe st Usable are less than optimum . The ITS has been Frequency (or Lowest Usable Broadcast supporting an NTIA initiative to the Band) . LUF were produced for each antenna Federal Communications Commission that the and its associated bearings and broadcast channel spacing for AM broadcasting be reception location for each month at the reduced from 10 kH z to 9 kHz in keeping two solar activity levels . A tabular pre with a European and Asian decision to sentation of predicted parameters included adopt the 9 kHz channel spacing . As the circuit reliability (REL) , defined as part of this support, the Propagation the percentage of days within the mo th . � . Predictions and Model Development Group that an adequate signal-to-nolse ratlo lS has investigated and summarized the expected , the expected monthly median of various methods of computing MF skywave the hourly median field strength at the field strength . The methods include those receiver location (DBU) , and the monthly developed by the FCC , the CC IR, and the median of the hourly median signal-to European Broadcasting Union . This inves noise ratios at the receiver inputs (S/N ) . tigation and the results derived therefrom These parameters were determined as im have been documented in a report that is portant in the development of frequency presently in the draft form. schedules, the selection of antennas to estimate if broadcast signals would be The results of this investigation are being adequate in the presence of interference � used to determine methods that can improve and to measure circuit quality. The rell the prediction and specification of night ability parameter was also presented in a time MF skywave field strength . format designed to simplify the de termina tion of geographic coverage at a given MF Ad jacent Channel Interference Project . time for a given frequency and antenna . This project 's obJ ective was to determine Another format of circuit reliabil ity wa s the adj acent channel interference poten developed to estimate the portion of the tial resulting from a reduction in the day a given frequency would provide sat MF frequency channel spacing from 10 kHz isfactory reception in a given area . 129 to 9 kHz . Four elements were needed to typical of what the average consumer might achieve this objective . First, industry purchase, and hence our test data repro acceptable standard measurement techni duces the potential interference problems ques for the performance of commercial AM faced by consumers . receivers had to be identified . Secondly , approximately 50 commercial receivers were Adjacent Channel Stations . 5337 AM Broad subjected to performance measurements and cast stations were analyzed for geographic the measurements summarized . Thirdly , proximity to other stations broadcasting the number of adjacent channel stations on adj acent channels . Cumulative distri where groundwave service area might pos butions were made parametric in nighttime sibly be adversely affected by a 9 kH z and daytime transmitting powers. MF channel space , wa s summarized . Lastly , the overall potential impact of 9 kHz Overall Potential Interference of 9 kH z channel spacing was determined on the AM Channel Spacing. From the tests on AM service area and reported . receivers, it appears that, to maintain the same audio frequency protection ratio as Radio Performance Tests . With respect to enjoyed on the present channel spacing , the the time constraints on the project, three rftdio frequency protection ratio needs to tests were deemed germane in evaluating be increased by 2 or 3 dB on the average . potential receiver interference from the proposed channel spacing reduction . The Directional Antenna Studies. The proposed first was the obj ective two-signal mea change in the allocation bandwidth (from suring method for the determination of 10 kHz to 9 · kHzl in the medium-frequency radio frequency protection ratios . This broadcast band would require that a large method of testing is found in CCIR Report number of broadcast stations change their 399-2 "AM Sound Broadcasting ." This is o�erating frequencies . One plan that has essentially a two-signal method consist been proposed would require changes in ing of modulating successively with a frequency allocations of 1 kHz to 4 kHz given modulation depth , the wanted and de�ending upon the present operating fre the interfering signal by a standard quency of the broadcast station . This shaped noise signal , the spectral ampli listing , showing the proposed new operating tude of which corresponds to modern dance frequencies , is shown in Table 3-2. music . The second tests were called SINAD measurements as described in the A part of the study being conducted by the EIA Standard RS-204-A. SINAD is defined Institute for Telecommunication Sciences as is concerned with the dollar cost to broad casters for changing their operating fre �ignal + noise + distortion quencies in accordance with the proposed. noise + distortion plan. In the case of broadcast stations without directional antennas , this cost can and is a meaningful measure of a receiver 's be easily determined as being the cost usable sensitivity , although the SINAD of new· crystals for transmitters and data does not directly relate to the monitoring equipment plus the cost of interference problems associated with a installing them in the equipment. New reduction in channel spacing . antenna impedance measurements should not be necessary since antenna impedance The th ird set of tests was to determine curves for �he present frequency should the selectivity of the test receivers . s�an the new operating frequency . The selectivity of a receiver is a measure of its abi lity to discriminate In the United States , because of the need between a wanted signal , to which the for many broadcast stations to serve the receiver is tuned , and unwanted signals . needs of the many communities and ethnic The single signal-selectivity measure grou�s , the medium-frequency broadcast ment wh ich was used in this test is band is very crowded and the use of direc referred to as a receiver bandwidth test. tional antennas which protect other sta The selectivity curve associated with a tions on the same frequency from inter particular radio has a definite effect �erence whi le making it possible to serve upon the interference problems associated a community has become prevalent. Origi wi th reduced channel spacing. nally directional antennas were utilized for nighttime operation when skywave Te st Receiver Selection . Approximately interference between stations on the same 50 radios were purchased from local re or adj acent channels became a problem , tailers for use in this testing program but the use of these antenna systems has and were tested in an "off the shelf" been greatly extended to permit daytime condition . No attempts were made to opti stations to operate in local areas. The mi ze the receiver performance with the result of this practice is the existence exception of the car radios where the of a very large number of stations using tr immer capacitor was adj usted for optimum directional antennas . high frequency performance . The price of these radios varied from $5.00 to about The determination of the cost to the broad $100 .00. These receivers are considered caster of making small (1 kHz to 4 kHz) 130 Table 3-2. Proposed 9 kHz Frequency Allocation Plan Nearest Nearest Nearest Present f New * f !':,.f Present f New * f M Present f New * f M kHz kHz kHz kHz kHz kHz kHz kHz kHz 540 540 0 900 900 0 1260 1260 0 550 549 -1 910 909 -1 1270 1269 -1 560 558 -2 920 918 -2 1280 1278 -2 570 567 -3 930 927 -3 1290 1287 -3 580 576 -4 940 936 -4 1300 1296 -4 585 945 1305 590 594 +4 950 954 +4 1310 1314 +4 600 603 +3 960 963 +3 1320 1323 +3 610 612 +2 970 972 +2 1330 1332 +2 620 621 +1 980 981 +1 1340 1341 +1 630 630 0 990 990 0 1350 1350 0 640 639 -1 1000 999 -1 1360 1359 -1 650 648 -2 1010 1008 -2 1370 1368 -2 660 657 -3 1020 1017 -3 1380 1377 -3 670 666 -4 1030 1026 -4 1390 1386 -4 675 1035 1395 680 684 +4 1040 1044 +4 1400 1404 +4 690 693 +3 1050 1053 +3 1410 1413 +3 700 702 +2 1060 1062 +2 1420 1422 +2 710 711 +1 1070 1071 +1 1430 1431 +1· 720 720 0 1080 1080 0 1440 1440 0 730 729 -1 1090 1089 -1 1450 1449 -1 740 738 -2 llOO 1098 -2 1460 1458 -2 750 747 -3 lllO ll07 -3 1470 1467 -3 760 756 -4 ll20 lll6 -4 1480 1476 -4 765 ll25 1485 770 774 +4 ll30 ll34 +4 1490 1494 +4 780 783 +3 ll40 ll43 +3 1500 1503 +3 790 792 +2 ll50 ll52 +·2 1510 1512 +2 800 801 +1 ll60 ll61 +1 1520 1521 +1 810 810 0 ll70 ll70 0 1530 1530 0 820 819 -1 ll80 ll79 -1 1540 1539 -1 830 828 -2 1190 ll88 -2 1550 1548 -2 840 837 -3 1200 ll97 -3 1560 1557 -3 850 846 -4 1210 1206 -4 1570 1566 -4 855 1215 1575 860 864 +4 1220 1224 +4 1580 1584 +4 870 873 +3 1230 1233 +3 1590 1593 +3 880 882 +2 1240 1242 +2 1600 1602 +2 890 891 +1 1250 1251 +1 * According to the 9 kHz spacing plan used in Regions 1 and 3. 131 frequency changes in accordance with the SECTION 3.5. APPLICATIONS proposed plan is not as simple with direc tional arrays . These antenna arrays range The constant study of EM wave transmission from simp le two-element arrays to arrays characteristics, the development of up-to with as many as twelve elements and from date theoretical and empirical models, and linear arrays to arrays with more compli the study of real-world telecommunication cated physical arrangements. Changes in problems lead to state-of-the-art applica operating frequency alter the electrical tions for telecommunication uses . This heights of the antennas, the electrical section deals with a variety of programs spacing between elements of the array , and wh ich show the broad spectrum of applied the phase shifts in transmission lines and· electromagnetic sciences. in phasing and matching networks . The costs of frequency changes are determined 3.5.1. Antennas and Radiation to a large extent by the engineering costs of realigning these arrays and the complex San Clemente Over-the-Horizon Radar. Some ity of requirements imposed by the Federal years ago ITS built a new phased array , Communications Commission . over-the-horizon radar on San Clemente Island off the coast of California . This Theoretical computations of the change in used a new concept where each antenna was the radiation patterns of a large number fed at the base of the antenna tower by of broadcast stations have been made for its own transmitter as shown in Figure 3-28. frequency changes of 1 to 4 kHz and have The hostile environment of San Clemente--- shown the pattern changes to be minor . Island (mainly the salty sea breeze) had caused major corrosion of the antenna and To provide experimental verification of transmitter system. On-site repairs of the theoretical findings , the operating the transmitters were deemed impossible frequency of radio station WLBH in Mattoon7 due to lack of facility , so the 25 trans Illinois , was changed from 1170 kHz to 1166 mitters were returned to Boulder for re kHz and to 1174 kHz during the test period furbishment and design update . from 1 to 5 am on two nights . WLBH uses a 4 tower linear directional antenna The transmitters were returned to the array . The licensed operating parameters Island in June of 1979. The systems were for the directional were used at each of installed , phased , and calibrated and the test frequencies . A Delta in-line successful experiments having to do with bridge was used at the common point to ocean surveillance were conducted in July assure that the licensed input power was 1979 under the dir·ection of the Naval obtained at each frequency . Measurements Research Laboratories , Washington , D. C. were made at three points on each of twelve radials for each of the three fre Kodiak Site Study. The U. S. Coast Guard quencies . communication station Kodiak is located on Kodiak Island , Alaska , and due to its It is interesting to note that the direc location is very critical to nautical tional wa s realigned on each of the fre communications in the northern Pacific and quencies in less than 1.5 hours by engi the Alaskan region . The responsibilities neering personnel of the station for the of communication station Kodiak currently most part using the front of the panel include : communication to/from all Coast controls of the phasing gear . Guard vessels in the Northern Pacific/ Alaskan region including aircraft on all The field strengths measured on the radi routine and emergency missions , reports als varied more than the predicted values. from foreign fishing vessels regarding It is felt that the deviations can be ex location and catch within the 200-mile plained as being due to the fact that limit , continuous guard on several MF and phases and current ratios were not exactly HF distress and calling frequencies , the same on the three frequencies and that continuous monitor of the AMVER (Automated sampling for the monitoring equipment was Mutual - Assistance Vessel Rescue ) system, located at the tower bases . It wa s felt and assorted other duties as needed such that the original values of field strength as phone patches , land lines , etc . could have been restored with further minor adjustment of the array . This was The proj ected future operational require not possible because of the limited author ments for communication station Kodiak ization of two four hour periods in which indicate a greatly increased leve l of to perform the tests . activity due to a variety of factors . Some of these factors are increased oil A full report on the project and a dis exploration and tanker traffic , an in cussion of the alternative procedures for crease in the number of Coast Guard patrol implementation of the proposed frequency vessels and aircraft in the Alaskan region , change with trade-offs which will greatly a possible 200-mile pollution control , and influence the cost to broadcasters is others. planned . 132 CXl N I ("') Q) H ::s 0'1 ·.-I .... 133 Due to the strategic location of the com Poor Coverage Areas - The few cases of munication station and the need for im spotty , poor communications currently ex provement of the physical plant , ITS wa s perienced (southeast Alaska , the Aleutian requested to undertake a study of the chain) may be due to the terrain in the antenna siting at the commun ication sta vicinity of the ship . The use of a hori tion . An unpublished report was prepared zonta lly polarized antenna aboard ship that addressed the question of both MF may alleviate the problem. and HF propagation to various regions of the Northern Pacific/Alaskan region con Antenna Polarization - The simp lest and sidering the location of the communication mo st effective way of dealing with the station with regard to the ocean areas poor site location is to use horizontal J and the topography of Kodiak Island . polarization for all but the lowest fre Surface-wave propagation predictions were quencies and shorter circuits . made for the MF frequencies and were des cribed in previous ITS annual reports . Antenna Matrices - It is recommended that two new antenna matrices be insta lled at Skywave propagation predictions were made the transmitter site to replace the current for the HF frequencies , considering the "patch-panel". One matrix should be of ocean regions of interest and a set of the manual type , switchable at the trans seasonal , diurnal , and solar activity mitter building, and it should be used to conditions. One output of these predic couple the slow-tune (ST) transmitters tions is a histogram of the optimum fre to some of the general purpose or fixed quency use. In addition , the associated tuned antennas . This matrix is shown in distr ibutions of take-off angle for each Figure 3-31 with the recommended trans frequency were computed . These predictions mitter and antenna ensembles . The second also were described in a previous annual matrix should be remotely controllable report. from the operations building . It would couple the proposed quick-tune (QT) trans Predictions such as those just described mitters and the special-purpose or high are used in determining the required gain antennas . This matrix is shown in antenna system. The greatest problem at Figure 3-32 . The 3 x 3 matrix currently the Kodiak transmitter site is the local used with three AN/FRT-89 MF transmitters topography . The horizon elevation angle is quite adequate and should be retained as observed from the center of the Buskin as is . Table site can be as high as 12°. BOM Analytic EM Waves . Various subsurface A site survey was made to determine the electromagnetic wave problems have been station operations and to view the topo analyzed for the U. s. Bureau of Mines . graphic situation . ITS has reviewed the The applications have been in mine communi predicted data, the existing physical cations and in electromagnetic methods for plant , and topography . The following nondestructive testing of mine hoist ropes . recommendations were presented in a final report. The possibil ity of transmitting signals from depth in a bore hole to a drill Operational Configuration - The proposed operator has been studied . A toroidal operational configuration is considered to coil wh ich completely encircles the drill be efficient and more versatile than the rod will excite axial currents on the current one (see Figures 3-29 and 3-30) . drill rod which wi ll propagate to the The new configuration should be capable surface . Both the propagation along the of handling the expected traffic . The rod and the input impedance of the trans proposed "quick-tune" transmitters that mitting toroid have been analyzed for need to be acquired should be remotely frequencies from 1 to 3000 Hz . It was controllable . The AN/FRT-39 's could be found that a thin insulating layer on the used as the "slow-tune " transmitters in drill rod will greatly decrease the the proposed transmitter upgrading pro required input power . gram. Nondestructive testing of mine hoist ropes Transmitter Power - The 10 kW (AN/FRT-39) is an important problem in mine safety . currently used is indeed a factor in deal Electromagnetic methods involving both ing with the poor site location , although solenoidal and toroidal excitation of wire 1 kW may be sufficient for the shorter ropes have been analyzed extensively . A range circuits tbat involve the higher system involving solenoidal excitation and elevation angles . Since this is difficult multiple sensing coils appears to be most to predict, it is suggested that lower promising . The effect of rope velocity power be tried for a time to determine has also been analyzed and is found to be wh ere and when it can be used . It would relatively unimportant except for extreme be good to retain one or more of the 40 kW cases of high velocity or very thick (AN/FRT-40) transmitters for emergency ropes . situations . Hydro-Quebec , the province-owned distri butor of electric power to almo st all of 134 Ope rating Transmitters and Use Transmitters and Use Position Operating Position System Control Net � � System Control Net II QT :J II � ''•••i III Voice AMVER r-:·�CW AMVER IV Unclassified Unclassified RATT RATT IV CW '" I Air- Vlw I to-Ground Voice v Air�to-Ground "" � Air-to-Ground Voice Air-to-Ground Voice & CW VI � �� � __voice I QT :J"oko VI I ST MFCW L IVII MF CW Figure 3-29. Cur£ent operating positionjtransmitte� Figure 3-30. Proposed operating position/transmitter relationships . relationsbips showin9 the use of slow tune {_S T)_ and quick. tune (QT ) t'l;ansmitters . OPERATING POSITICN TRANSMITI'ER3 MATRIX ANTENNAS '\Tl l IDI'HWID (2-9 MHZ) Q)NICAL M:IDPOLES OPERATING POSITICN TRANSMITI'ER3 MATRIX ANTENNAS II HIQ!-BAND (7-28 MHZ) < I o:JNICAL M:NOPOLES I "V} roi'ATABIE LOG PERIODIC$ II I 5 30 ,-=} SLEEVE 2-6 �1Hz 'IC I I I III "V 'ICI 540 (NEW) SLEEVE 3-9 MHZ � H fv\!\"j lW_ SLEEVE 4-12 MHZ IV I'ATRIX IV I>JJTCW\TIC INVERI'ED VEE 1 I� �TRIX {� CNE.W) (t£W) INVERI'ED VEE 2 I-' v w "' v INVERI'ED VEE 3 { VI r-arl------1 I r SLEEVE , 2-6 MHZ HORIZCNTAL IXlUBLET 6 [ � �. '-" ffi' I I T HORIZCNTAL OOUBIET 18 SPAf£S CXlNICAL M:NOPOLE ' 2-8 MHZ VI HORIZONI'AL OOUBIET 25 : ..:� ,! Er-£1IDlCY r 1---- == · Mm' WIDE-BAND -'--� � OOUBIEI'S - - ;figure Reco�ended automatic matrix. SPAIES { �' 3-32 . Figure 3-31. Recommended manual matrix . Quebec , is planning an extensive moderni makes the corresponding earth-space pre zation of its land mobi le radio system . dictions of attenuation due to rainfall Under the project Mobile Aids , ITS devised is entitled DEGP77 , and has recently been computer aids to help the design of the user-oriented through the addition of new system and supplied these aids in comment cards and the preparation of a the form of computer programs able to special deck of cards for general access operate at the sponsor 's facility. by potential users . The project is now complete . The sponsor Solar Power Satellite Ionosphere Modifi now has operating programs wh ich store catiOn� part of its program in seeking and retrieve large amounts of data in a alternative energy sources to meet the variety of formats and others which use needs of the United States , the Department a digitized topographic file to estimate of Energy is undertaking a program to received signal levels on point-to-point assess the impact of the operation of a links and on roads and areas serviced by Satellite Power System (SPS) upon the mobile base stations. atmosphere and ionosphere . The SPS is configured as 60 satellites in geostation 3.5.2. Transmission Through the ary orbit collecting radiant solar energy . Atmosphere : Applications This radiant energy is to be converted at the satellite into microwave energy and Consolidated Model for Earth-Satellite down-linked to antennas at the surface Links . The allocation of frequency assign of the earth which will rectify the micro ments is one aspect of radio spectrum wave energy and convert it into DC for management which is very much concerned inclusion into power grids . As the micro with the problem of determining coordina wave energy passes through the ionosphere tion distance (the minimum permissible from the satellite , there exists the pos geographical separation between co-channe l sibility that the ionosphere wi ll be stations without formal coordination). heated by ohmic processes by the microwave Determination of this distance requires energy . This heating could result in the prediction of the occurrence of propaga formation of electron density irregulari tion conditions which support interfer ties in the F region and in enhanced ence fields . NTIA has initiated a study absorption of radio waves in the D region . to develop engineering methods for the The effects of such heating upon telecom prediction of the potential for interfer munications systems are illustrated in an ence fields . A recent report ("Recent artist 's concept in Figure 3-36. Progress in Duct Propagation Prediction" by Dougherty and Hart, IEEE Trans . AP -27, The Propagation Predictions and Model July 1979) reviews the available meteoro Development Group is responsible for logical data on ducts , propagation pre coordinating and managing the DoE program diction methods , and preliminary estimates addressing the potential effects of SPS of expected interference fields . operation on the ionosphere and ionospheric depenment telecommunications systems . A Figure 3-33 illustrates the type of unusu program of research and exploratory devel ally strong fields (to within 20 dB of the opment has been developed and coordinated free-space level) that can occur in the with scientists and policy-makers through presence of elevated atmospheric layers out the United States . Current activities over transhorizon paths which normally pro are directed toward three specific areas duce rapidly fluctuating fields attenuated of investigation . First , the impact of by an additional 40 to 60 dB . the SPS 8peration upon telecommunication systems that rely on the D region of the Previous years ' activities have extended ionosphere wi ll be studied . This is being the Dutton-Dougherty (modified Rice-Holmberg) accomplished by simulating the SPS iono rainfall prediction model by detailed map- spheric heating effects using the HF pings of the prediction parameters (total Platteville Ionospheric Heating Facility rainfall, M, ratio of thunderstorm days and measuring the performance of the tele- to total rainy days , S, etc. ). Last year 's communication systems whose energy passes efforts produced estimates of average-year through the heated ionosphere . Telecommu- rainfall and the year-to-year variation nication systems such as OMEGA , LORAN-C , in Europe. This year , a report ("Year-to- WWVB , WWV , and AM Broadcasting signals Year" Variability of Ra infall for Microwave will be monitored when the Platteville Applications in the U.S.A. " by Dutton and heater is turned on and off in an effort Dougherty , IEEE Trans . COM-27 , June 1979) to deduce what, if any , heating-related presents similar estimates for the U.S.A. effects are observed . For example, Figures 3-34 and 3-35 show the contour mapping of the U.S�for the A second effort is directed toward gather one-minute rainfall rate expected for 0.1% ing experimental data to aid in determining of an average year , R1 (0.1%) --expected for the phys ical mechanisms responsible for a cumulative total of 8.75 min during the the heating of the ionosphere . This effort year--and the contour mapping of the year relies heavily upon the use of the Incoherent to-year variability in this 0.1% rainfall Scatter Radar at Arecibo , P.R. , in order rate, 81 (0.1%) . A computer program that to determine the changes in electron 137 185.75 MHz SIGNALS RECEIVED AT GBH 0 dBM is the long-term-median KOMC troposcotter field level H05 d8m) The KOMC free-spcce-field level is 65d8M or -40 dBm 0830 0930 MDT 20 I-' w OJ 0730 0830 0930 1030 MDT long-term-median is 0 dBM long-tenm-medion is -15 dBM 20 -1= riH' ...... 'I kf I"IM. Figure 3-33. Strong fields (40 dB and more above the long-term median of Q dBml that occur on tran3horizon paths in association with elevated atmospheric (.refractivityl layers as potential interfere�ce fields . Cs ' f-' w \0 5.0 ': '-..... _,...... __ 'i ---- y' \ 10.6 ., (. 8.0"%'"� HAWAII 7.J �.7 -\ �Ql v ( figure 3-34 . Contours of R1CO.l%} , the t T 1 min rainfall rates in mm(hr predicted for 0.1 percent of an average year �n the Q.S.A. I I ' rs � l I <;J =· �\ I '&I r-. 7 \? C> I lL"l I q \ c7 C::> CJ \ \). f-' � 0 i �1I ALASICA 0 50 1 00 oo � "0r:. Figure Contours of the standard deviatton in mm/1'\r o;e ttl.e. ear-to-year variation 3-35 . SRl (0 .1%} , y in the t = 1 min rainfall rate , R (0 .1%} , for 0.1 percent of all hours of a year . 1 '0' COMMUNICATIONS F REGION ---L - ------...... __ ...... __ SPS 0 REGION IONOSPHERIC IRREGULARITIES f-' .t>. f-' 414 Q �� Jfc � )) Figure 3-36. Illustration of the possible effects of the operation ot the SPS on the ionosphere and telecornrnunic�ions systems . density and electron temperature due to range for a variety of microwave commun i ohmic heating . A final effort is directed cation links . The cross-hatch area repre toward the development of theoretically sents the range of errors measured for valid models of the SPS-induced ionospheric the systems tested . The area labeled heating effects . The theoretical models "mitigated" shows the reduction in degra are needed in order to extrapolate the dation due to the following techniques. experimental results obtained at heating frequencies in the HF portion of the 1. The receiving antennas of the spectrum to those anticipated at the SPS microwave systems were changed to reduce operational frequency of 2.45 GHz. their vertical gain and thus reduce the amount of interaction with the SPS power Solar Power Station EMC Analysis . This is beam . a continuing program sponsored by the De partment of Energy to study the potential 2. Notch filters for the SPS center RFI/EMI effects of a proposed Solar Power frequency at 2.45 GHz and second harmonic Station (SPS) . These satellites would at 4.96 HZ were used to reduce signal convert solar energy into DC voltage which coupling to the input signal amplitudes. would drive high power microwave sources to produce a high energy microwave beam at 3. Shielding of modules within the 2.45 GHz . The satellite in geostationary systems were accomplished to eliminate orbit would beam the energy to a given physical apertures (slots or holes) receiving antenna (rectenna) on earth through wh ich SPS microwave energy could where the microwave energy would be con be coupled . verted to electrical energy for consumer use. One satellite is capable of producing 4. Signal and control cables were 5000 me gawatts of electrical power on the either shielded if energy coupling was earth . taking place or double shielded cables were used if normal shielded cables showed One of the first tasks was to calculate the SPS coupling effects . radiation pattern for the space antenna. The antenna is a phased array 1 kilometer Figure 3-43 shows the imaging efficiency in diameter with a 10 dB Gaussian amplitude of high resolution TV and infrared sensors taper across the aperture . It beams 6.85 used in security monitor applications as a GW of power using more than a hundred function of SPS illumination and mitiga thousand microwave klystrons each producing tion . The cross hatch again shows a range about 50-70 kW each. The pattern analysis of degradation representing a variety of is given in NT IA Technical Memorandum systems tested and a variety of configura TM-79-5. Figure 3-37 shows a computer plot tions of sensor systems . The mitigation of gain versus angle from boresight for techniques used included an optical apera the proposed spacetenna . Field intensity ture grid shield placed in front of the plots for the continental United States receiving optics in an optical defocus were calculated for a various number of location with a me sh size of 1/2" x 1/2"; SPS satellites . Figures 3-38 through an aluminum shield was used over other 3-40 show a 1, 5, and 10 satellite dis sensitive areas with no openings larger tribution . Figure 3-41 shows a hemisphere than 1/4 " in diameter ; dual coax was again distr ibution for a ro-8atellite case . used to keep cable coupling at a minimum . From the field intensity maps came an Figure 3-44 shows the effects of SPS beam estimate of the range of microwave energy coupl ing into microprocessors and mini that other electronic equipment and systems computers. A large variety of systems would be exposed to . This led to exposure were tested giving a wide range of degrada levels that would be used in the determina tion responses to SPS energy coupling re tion of the functional and operational presented by the cross-hatch area . However , degradation of electromagnetic systems the measured errors were reduced to an (communications , radars, navigation aids , acceptable leve l by the use of wire grid etc. ) and other environmental sensitive shielding over physical slots and holes equipments and systems (computers , sensors, larger than 1/2 " x 1/2" ; using single electronic medical instruments and devices , point ground system for all modules; the etc. ). Subsequent tasks addressed mitiga use of dual coax in all message and con tion techniques for degraded systems with necting cables ; using single point ground some actual measurements to validate for cable system; and using power and bias estimated operational degradation. supply filters for source and functional module ends to eliminate SPS EM energy Figures 3-42 through 3-44 show : normal from coupling through supply voltages . error limits on some candidate systems with no SPS illumination ; the percent loss These are only a few representative types in effic iency in an SPS environment as a of systems under study , and a complete re function of distance from the rectenna port will be written to show the coupling site; and the reduction of effect when modes and mitigating strategies for a wide certain mitigation techniques were used . variety of systems . Figure 3-42 shows the normal effic iency 142 c 0 (.!) 89 90 91 92 93 94 95 Theta Figure 3-37 . Gain versus angle from boresight . On-axis gain is about 87.65 dB. Figure 3-38. SPS single satelLite power density distribution , mw/cm2 . 143 - - --� --;�- l:,> � ·.1'1_...... , <;) q 8 0- .1 ·w -� . - - I I I 1-' � � Il l I � ·��o-a,.-luJ�----i------t�e,p-;;.��__jvp,--lo-7 ..,\ I I I : . ·:: ·: - -·�__ } Figure 3-39 . Field intensity distr,ib ut;Lon, rnw(cm2 , 5 receiveJ: s.:j.te.s . ·-�-:-:-- --··--�.- --·-·- ���.-- 1-' 10-��-.-. 'c·�,._· ,. Ul • !0 { �1\.\ 10� (; rnw/(•t; to""�> nlwl(!lr . ' 10 rnw·cm • 10 �rnNk rt' u. 10 ;> mw/( m H.-�c t,'!'l')t1 '\ ,...... •' · '· ,. r· \__,.) ____ .- ./ rf/ ..4- � .' \ -::::: '· ...;) 4 Figure 3-40. Field intensity dist rji:Pution for lQ SPS ;t"ece.iving sites . 2 Figure 3-41 . Field intensity distribution , mw/ cm , 10 receiver sites . 146 80 �0 60 > (.) c: Q) (.) - - UJ *• Amplifier Notch Filter • Circuit Mods Source ITS I I V/M 4.5 2.7 0 0 16 32 Kms From Rectenna t PN79 01421 2/21 Figure 3-42 . SPS results - electromagnetic compatibility effect of MPTS beam on M-W communications links . 80 �0 > (.) c: Q) 60 (.) - - UJ c:C'l 40 C'l ca *• Shielding E • Circuit Mods 20 Source ITS I I V /M 4.5 2.7 0 �------�------� 0 16 32 Kms From Rectenna t PN79 01421 3 1 21 Figure 3-43. SPS results - electromagnetic compatibility effect of MPTS beam on security systems (hi-resolution TV & IR sensors) . 147 80 �0 60 > (.) � ... ;:::, (.) (.) 40 Figure 3-44. SPS results - electromagnetic compatibility effect of MPTS beam on microprocessor accuracy . 148 Another area of concern was the potential c. M. Rush, are both members of ITS 's degradation in operation of existing and Applied Electromagnetic Science Division . planned satellites both in Geostationary Earth Orbit (GEO) and Low Earth Orbit (LEO) . Areas of specific concern to CCIR in which The GEO satellites investigated are given ITS personnel play key roles include : in Figure 3-45 and the SPS amplitude ionospheric mapping; ionospheric operation thresholds where problems start to occur al considerations; skywave field strength are given in Figure 3-46. calculations at frequencies above 1.6 MHz ; microwave system design ; fading phenomenon A detailed analysis of potential effects on LOS links ; the role of rainfall in on an INTELSAT communication satellite is microwave system performance and interfer given in NTIA Technical Memorandum 79-5 . ence; and the ionospheric and tropospheric The conclusions drawn from these analyses aspects of radio noise. appear to indicate that the SPS spacetenna 's extremely narrow beamwidth will not cause In addition , ITS personnel actively parti potential interference problems with cipated in the CCIR Special Preparatory neighboring satellites . Meeting held in Geneva , Switzer land , during October and November 1978, and participated The LEO satellites such as LANDSAT and GPS in a Region 2 telecommunications meeting have a much higher potential for SPS effects held in Panama in March 1979 . These since they have a high probability of meetings were held to develop reports to passing through the power beam of an SPS be used by Administrations preparing for from time to time . Figure 3-47 shows the the General World Administrative Radio SPS microwave beam geometry-ar-a GPS Conference . satellite orbit altitude . The time s shown are the times the satellite wi ll be sub jected to the level of intensity indicated or higher . That is , the satellite will be subjected to fields greater than 4 2 mw/cm for 1.35 seconds . The potential problems could effect S band receivers, on board signal processing , altitude con trol circuits , and EED circuits . The main signal coupling would come through the S band antenna that looks away from earth and toward an SPS , and through cooling louvers as they open to cool electronic circuits behind them. A GPS functional impact modes diagram is shown in Figure 3-48. There are a number of mitigating techniques such as power supply filtering, wire mesh behind open louvers, filtering ahead of the receivers , etc. , that can be used to allow acceptable performance of most satellites for the few seconds they would be in the power beam . This is an ongoing project which will look at other satellites in an SPS environment, analyze the possible use of higher opera ting frequencies for the Microwave Power Transmission System (MPTS) , continue to study effects and mitigation techniques for many types of EM and electronic systems and devices, compute emissions expected from the MPTS including noise and harmonics , and other tasks involved in understanding the SPS EM environment and how compatibi lity can be achieved . 3.5.3. CCIR Participation Support to the International Telecommuni cation Union 's (ITU) advisory Interna tional Rad io Consultative Committee (CCIR) was provided by ITS personnel in the fields of tropospheric (Study Group 5) and iono spheric (Study Group 6) propagation. The U. S. National Chairmen of CCIR Study Groups 5 and 6, Drs . H. T. Dougherty and 149 1. SATCOM - 119 WJ 135 WJ 132 W 2. COMSTAR - 128 WJ 95 W 3. WESTAR - 99 WJ 123 .5 WJ 91 W 4. TDRSS - 171 WJ 41 W 5. MAR I SAT - 15 WJ 176 .5 EJ 73 E 6. SBS - 122 WJ 106 E 7. INTELSAT - 16 ,5 E 8. AN IK - 108.5 WJ 114 W Figure 3-45 . Potential victim satellites . 1. SATCOM : -62 dBm - -77 dBm - f0; f2 2. COMSTAR : -60 dBm - -74 dBm - f f0; 2 3. WESTAR : -58 dBm - -74 dBm - f f0; 2 4. MARISAT : -62 dBm - -76 dBm - f f0; 2 0 5. SBS : -62 dBm - -78 dBm - f f0; 2 6. AN IK: -62 dBm - -78 dBm - f0; f2 7. TDRSS : -54 dBm - -68 dBm - f0; f2 Figure 3-46. The SPS amplitude thresholds for GEO satellites . 150 10 N E ... ' 3: E . >- I- en 2 w I- 2 Q ..... w ...... DISTANCE FROM BORE SITE, km Figure 3-47 . SPS microwave beam geometry at Navstar orbit amplitude . THERMAL CONTROL CIRCUIT &. CABLE .------EB ... LOUVERS APERTURES SOLAR PANEL SPS INCIDENT PWR SUN &. EARTH ATTITUDE, STAB, �------' SENSORS CONTROL VOLTAGE, � CIRCUIT PWR NOISE � PWR CONTROLS Figure 3-48. SPS functional impact modes. 151 ANNEX I ITS PROJECTS FOR FY 79 ORGANIZED BY DEPARTMENT AND AGENCY Project Title Leader Title Leader AGRICULTURE , DEPARTMENT OF COl!MERCE , DEPARTHENT OF (DoC) (Continued) 9104384 Communication Support Program McQuate National Telecommunications and Information Administratio n (N TIA) (C ontin ued) COM11ERCE , DEPARTMENT OF (DoC) 9108246 MF Long Distanc� Interference Lloyd 9108247 Platteville Repairs Lucas Ma ritime Administration (MARAD ) 9108249 Directional Antenna Study Stewart 9108250 Adjacent Channel Interference Washburn 9102419 MARAD Assistance deHaas 9108260 FCC Proceedings Williams 9108265 Public Broadcasting Hufford National Bureau of Standards (NBS) 9103551 IACP/NBS Test Program Bolton DEFENSE , DEPARTHENT OF (DoD) National Oceanic & Atmospheric Administration (NOAA) Air Force Communications Sys tem (AFCS) 9103417 Weather Radar RFI Surveys Tary 9103484 Automatic Measurement System 9103537 SPS Ionospheric l!odification Rush Upgrade wortendyke 9104380 LOS Fade 8-GHz System Hause National Telecommunications and Information Administration (NTIA) Air Force Sys tems Command (ESD) 910llll FM Frequency Assignment & 9103479 EFAS/PEP II Program Skerj anec Criteria Evaluation Haakinson 9103528 HF Ionospheric Scattering 910lll2 Spectrum Tradeoffs - Mobile Berry Study Violette 910lll3 Spectrum Consuming Property of 9103564 CONUS OTH-B Propagation Rosich TV-FM Receiving Antennas Matheson 9104371 TRC Tropographic Tests Hubbard 910lll4 Evaluation of UHF TV 9104373 EFAS/PEP II Program Analysis Skerj anec Receivers Adams 910lll5 Spread Spectrum Application of Air Force Sys tems Command (RADC) LMR Juroshek 9101116 Multiple Interference Effects 9103530 RADC Technical Support Hubbard of LMR Receivers Juroshek 9103562 HF Ground Wave Wait 910lll7 TV Spectrum Planning Techniques Hufford Air Force Spa ce & Missile Sys tems (SAMSO) 9101118 Theoretical FM Performance/ Interference Spaulding 9101463 Buried Antenna Studies - MX 910lll9 Ad jacent Channel Interference Nashburn Phase II FitzGerrell 910ll20 Directional Antenna Study Stewart 9104151 Data Communications Seitz Air Force Miscellaneous 9104152 Guided Wave Communications Bloom 9104153 EHS Communications Hull 9103441 I!SR-Tl Multiple Receiver 9104154 Rural Telecommunications Hull System Barghausen 9104156 Regular Impact on Direct 9103492 TAC-Signal Analysis System Barghausen Satellite Communications Nells 9103563 Polar Ionospheric Propagation Rosich 9104157 Technical & Economic Aspects 9103565 Topside HF Noise Rush of Small Earth Station 9103569 OHD Target Detection Ott Development l�e lls 9104393 LF Radio Propagation 9105179 Engineering/Technical Measurement Kissick Evaluation McManamon 9105180 Characterization of Army Communication Command (USA/CC) Protection Contract Lemp 9105195 Technical Assessment of 9103382 Army Mob ile Automatic Receiver Green Thumb Nortendyke System Carroll 9105196 Local Loop Telephone 9103427 EMC Van , Part II Carroll Distribution Technology Bloom 9103434 Access Area Digital Switching 9106209 HF Sharing & Power Studies Rush Program Linfield 9106210 Satellite Spectrum Sharing 9103446 Applications Software McLean Study Ne lls 9103470 EMC Remote Extension Diede 9107219 Technical Subcommittee 9103474 Automated Digital Topographic Support Hull Data Techniques Spies 9107226 Spectrum Analysis Techniques 9103478 EMC Van , Part III Carroll & Support Hurray 9103491 Follow-on �la intenance Stewart 9107235 RSMS Operations Matheson 9103499 TAEMS Training 3 McLean 9107236 RSMS Deve lopment Matheson 9.103501 Application Enhancements Stewart 9108240 VHF/UHF Measurements in 9103505 Automated Field Intensity Urban Areas Grant Measurement System Haakinson 9108241 Review of Present AH Band 9103507 TAEMS Noise Measurement Spaulding Coverage Prediction 9103511 Voltage Tuned Filter Carroll Technique Rush 9103513 TAEMS Repair Parts s.tewart 9108242 Expansion of Model & Data 9103531 ADRES System Upgrade Harr Bank Washburn 9103532 15-GHz LOS Fading Hause 9108243 Propagation Mode l Terrain 9103533 Aircraft Effects Skerjanec Microwave System Ott 9103534 Channel Probe �leasurement/MW 9108244 Hodel Satellite-Earth Links Hubbard Hicrowave Links Dougherty 9103538 Verification Test Set Smith 9108245 1-le asurement of Fading 9103547 Digital System Performance Statistics & Error Rates Lucas Verification McQuate 153 Title LeadeJ; Project Title Leader DEFENSE, DEPARTMENT OF (DoD) (Continued) ENERGY RESEARCH & DEVELOPMENT ADMINISTRATION (ERDA) Army Communication Command (USA/CC) (Continued) 9103536 SPS RFI/EMI Analysis Grant 9104379 SPS Ionospheric Effects Rush 9103557 TAEMS Field, Measurement 9104388 DOE Platteville Heating Violette Consultation Matheson 9l04404 SECOM System Enhancement deHaas 9103559 Technical Concept Papers Gallawa 9103560 HF Communications Watterson 9103561 Command Post/SIG CTR Bus Linfield FEDERAL COMMUNICATIONS COMMISSION (FCC ) 9104390 NBS Antenna Interface Grant 9104407 Army Communication Network 9103539 CATV/ATC Interference Adams Analysis Lloyd 9104381 CB Intermodulation Interference Berry Army Research Office (ARO) 9l04382 HF Sharing Tests Lucas 9104385 TV Antenna Performance Matheson 9103550 DM-4/Calculator Software Matheson 9104386 TV Antenna System Performance Matheson 9104405 MM Wave Attenuation in 9l04394 FCC Channel Simulation Watterson Moist Air Liebe Army Hiscellaneous INTERNATIONAL COMMUNICATION AGENCY (ICA) 9103525 Spectrum Monitoring Unit Adams 9l0l499 Radio Propagation Predictions Agy 9103527 Frequency Extension of 910l501 Improved Prediction Formats Agy Spectrum Honitoring 9103524 Revision of HF Broadcast Capability Adams Methods Agy 9103544 Intervisibility Propagation 9103540 VOA Consulting Agy Loss �leasurement Haakinson 9l03542 Remote Access Computer Agy 9103545 Intervisibility Propagation Loss Measurements Thompson 9103555 30-300 GHz Communication NATIONAL AERONAUTICS & SPACE ADMINISTRATION (NASA) Links Thompson 9103558 Large Earth Terminal Antenna 9l04391 Radio-Optical Refractometer Thompson Measurement Matheson 9103568 Propagation Measurement Guidelines Hufford TRANSPORTATION, DEPARTMENT OF (DoT) 9104375 MM Workshop Thompson 9104377 Jammer S/I Ratios Paulson Federal Aviation Adminis-tration (FAA) 9104378 Short-Term Ionospheric Predictions Rush 9103489 Technical Support in Propagation 910439(; Wide-Band �l easurement DDAS Adams and Spectrum Engineering Hubbard 9104397 Wide-Band Measurement Data 9103526 Air Navigation Aids Johnson Analysis Hufford 9l04370 LPC Evaluation of Voice 9104398 Wide-Band Data Collection Hubbard Channel Pratt 9104374 ADF/PLC Interference Kissick Naval Research Laboratory (NRL) U.S. Coast Guard (USCG) 9102370 Proj ect NONESUCH Warner 9103508 Navy Optimum Communications Spaulding 9101532 Consulting USCG Kissick 9103556 Navy Refractivity Study Harler 9103488 KODIAK Antenna Improvement Kissick 9l03548 San Juan/ADAK Trade-off Kissick Office of Naval Research (ONR) 9l04 395 Puget Sound Coverage Kissick 9104406 EHF Attenuation of Air Liebe U.S. POSTAL SERVICE Pacific Missile Range 9l03529 U.S.P.S. Electronic Message 9103497 Ground/Air Propagation Service McManamon Predictions Gierhart 9l04389 U.S.P.S. Electronic Message 9103543 PMR Microwave Link Tests Hubbard Service McManamon Navy Miscellaneous OTHER 9103553 EHF Prediction Model Liebe 9l0l583 LF Mode ls Berry Defense Communications Age ncy (DCA) 9101585 GOES Equipment Certification Bolton 9101586 Tropospheric Predictions Johnson 9101534 MEECN Simulation Wattersol'. 9101587 Numerical Prediction Services 9103512 Glossary Update Hanson MFA Agy 9103566 DCS II Standards Development de Haas 9102580 Analysis Services Adams 9104399 DCS II Operating Performance 9102586 IONCAP Requests Tveten Criteria Linfield Miscellaneous Fed-eral Agencies National Security Agency (NSA) 9101504 HF Consulting Haydon 9101518 NSA Consulting Spaulding 9103466 Saudi Arabia HF Predictions Teters 9103567 HF/VHF Propagation Validation Teters 9103482 SECOM Communications Analysis deHaas 9104372 Ionospheric Mapping Study Po Kempner 9104401 High Altitude Topside Noise Rush Hiscellaneous Non-Federal Agencies 9104403 Computer �lodel Extension Hufford 9102378 Hobile Aids Hufford 9103521 Be ll Consulting Spaulding 9104376 Canal Zone RFI Survey Tary 9104383 IONCAP Goes International Lloyd 9104387 Voice Performance �!easurement Hartman 9l04392 Channel Simulator Tests Watterson 9104402 TADIRAN Channel Simulation Watterson . 154 ANNEX II ORGAN IZATIONAL DIRECTORY INSTITUTE FOR TELECOM!-!UNICATION SCIENCES NATIONAL TELECOl-!1-!UNICATIONS AND INFO�ffiT ION ADMINISTRATION , DEPARTMENT OF COl-!1-!ERCE 325 Broad>lay , Boulder , Colorado 80303 (303) 499-1000 (FTS dial 323 + extension) Name Ext . Room DIRECTOR 'S OFFICE (0/D) CROMBIE, Douglass D. - Director 4215 3020 UTLAUT , Wi lliam F. - Deputy Director 3500 3020 I'IALTERS , �lilliam D. - Budget and Accounting Officer 4414 3019 STONER , Russell B. - Publication and Technical Information Officer 3572 3009 WA IT, James R. - Consultant , also with NOAA and CIRES 6471 227 (RB 1) DIVISION 1 - SPECTRUM UTILIZATION MURRAY , John P. -Associate Director 4162 4533 1.1 Spectrum Analysis, Modeling & Services ADAMS , Jean E. 4301 4517 1.2 EM Environment Characterization MATHESON , Robert J. 3293 2221 1.3 Spectrum Planning Methodology HUFFORD , George A. 3457 4523 DIVISION 2 - SYSTEMS TECHNOLOGY AND STANDARDS HULL , Joseph A. - Associate Director 4136 2034 2.1 Evaluation of New Technology Developments BLOOM , Louis R. 3485 2245A 2.2 Systems Requirements Definition MORRISON , Ernest L. , Jr . 4215 3013 2.3 System Performance Criteria GATES , Harvey M. 3589 22 13A DIVISION 3 - APPLIED ELECTRO�ffiGNETIC SCIENCE LUCAS , Donald L. - Associate Director 3821 3421 3.1 EM Propagation Research and Analysis THOMPSON , Moody C., Jr . 3508 3442A 3.2 Advanced Communication Technology & Applications GRANT, William B. 3729 3447 3.3 Propagation Predictions & Model Development RUSH , Charles M. 3460 3411 DIVISION 4 - ADVANCED COl-!1-!UNICATION NETWORKS McMANAMON, Peter M. - Associate Director 3570 2-0323 4.1 Communications Protection McMANAMON , Peter M. Acting 3570 2-0323 4.2 Switched Networks McMANAMON , Peter M. - Acting 3570 2-0323 4.3 Specialized Networks McMANAMON , Peter M. -Acting 3570 2-0323 155 ANNEX III INSTITUTE FOR TELECOMMUNICATION SCIENCES NATIONAL TELECOMMUNICATIONS AND INFORMATION ADMINISTRATION DEPARTMENT OF COMMERCE Alphabetical Listing of ITS Employees August 15 , 1979 Name Ext . Room Name Ext . Room ADAMS , Jean E. 4301 4517 HANSON , D ..wayne 3573 2246 AGY , vaughn L. 3659 3441 HARMAN , John M. 3655 2030 AKIMA , Hiroshi 3392 2-0324 HARTMAN , IHlliam J. 3606 2210D ANDERSON , David P. 3506 2246 HAUSE , Laurance G. 3945 2230B ARCHULETA , Stephanie L. 4136 2030 HAYDON , George W. 3583 3420C AX , Carole J. 3748 22l8 HERSHEY , John E. 3748 . 2246 HILDEBRANDT , Thomas H. 3175 2230 HILL , David A. 3472 2209 BARGHAUSEN , Alfred F. 3384 3443 HOROI'II TZ , Renee B. 4162 4529 BEASLEY , Keith R. 3731 4528A HUBBARD , Robert 1'1 . 3414 2243 BEERY , Wesley M. 3501 3463 BERRY , Janet S. 4129 4516B BERRY , Leslie A. 4474 4528D HUFFORD , George A. 3457 4523 HULL , Joseph A. 4136 2034 HUNT , HO>lard D. 3730 2236M BLOOM , Louis R. 3485 2245A HYOVALTI , Duane c. 3447 3450A BOGLE , Robert W. 3130 2-0120 BOLTON , Earl c. 3104 2236M BROOKS , Minnie 4281 2245 JEFFREYS , Charlene E. 4414 3021 BYERS , John D. 4125 4520B JENNINGS , Raymond D. 3233 4528H JOHNSON , Mary Ellen 3587 4522C JUNEAU , Robert I. 4202 2222 CANADAY , Lois s. 3562 3413 JUROSHEK , John R. 4362 4528E CARROLL , John C. 3601 3459 CHAVE Z, Richard 3584 3430 CHILTON , Charles J. 3815 3420 KISSICK , William A. 4258 4520E COLEMAN , Susan J. 3883 3450 LANGER , Susan K. 4162 4527 CROMBIE , Douglass D. 4215 3020 LAWRENCE, Vincent s. 3211 2222 CROW, Edwin L. 3452 2-0324 LAYTON , Donald H. 3584 3430 LEMP , John 3713 2246 LIEBE , Hans J. 3310 3426 deHAAS , Thi js 3728 2030 DIEDE , Arthur H. 3103 3458B DOUGHERTY , Harold T. 3913 3453 LINFIELD , Robert F. 4243 2237 DROUILLARD , Patricia H. 4337 3015 LLOYD , John L. 3701 34 19M DUTTON , Evan J. 3646 3454C LONGLEY , Anita G. 3470 4521 LUCAS , Donald L. 3821 3425 ESPELAND , Richard H. 3882 3410M MADONNA , Nancy 3821 3421 MAJOR , Jeanne C. 4122 4520D FALCON , Glenn D. 436l 2222C MARLER , F. Gene 4321 3458A FARROW , Joseph E. 3607 2230 MARLOW, �l ichael M. 3175 2230 FLETCHER, Christopher M. 4162 4524 MARTIN , William L. 3195 3426 FRITZ , Olive M. 3778 2213 MATHESON , Robert J. 3293 2221 GALLAWA , Robert L. 3761 2217 MAYEDA , Kathy E. 3998 3420 GAMAUF, Kenneth J. 3677 3430 McCARROLL , Patricia A. 3883 3449 GATES , Harvey M. 3589 2213A McCOY , Elizabeth L. 4162 4527 GEISSINGER , Marcia L. 3500 3020 McLEAN Robert A. 3262 3462 GIBSON , Beverle J. 4215 3020 McMANAMON , Peter M, 3570 2-0323 GIERHART , Gary D. 3292 2222M McQUATE , Paul L. 3945 2230 GLEN , Donald V. 3893 2-0118 MELLECKER , Carlene M. 3330 3458A GODWIN , John R. 4122 4520D MILES , Martin J. 3567 2-0118 GOODKNIGHT , Frank A. 3998 3419 MILLER , Charles H. 4496 3454A GOULD , Beverly A. 3291 2219 MITZ , Albert R. 3513 3442 GRANT , l'li lliam B. 3729 3447 MI ZE , James ,., . , Jr . 4166 2218 GRAY , Evelyn M. 3307 2223 MOLLARD , Jean R. 3821 3421 GREEN , Robe>:t F. 3778 2213 MORRISON , Ernest L. 4215 3013 MURRAY , John P. 4162 4533 HAAKINSON , Eldon J. 4304 4511 HAIDLE , Leroy L. 3233 4524B NESENBERGS , Martin 3337 2210M HALE , Wi lliam K. 4474 4528F NEY , Linda 4125 4520'1l HANSEN , Ruth B. 3513 3442C HANSON , A. Glenn 4449 2223 157 Name Ext . Room Name Ext . Room OLSON , Marylyn N. 4136 2030 SPIES , Kenneth P. 3839 2234B OTT , Randolph H. 3353 3467 STEARNS , Charles o. 3749 3450 STEELE , Francis K. 3815 3458C STEWART , Arthur C. 3998 3419 PATTERSON , James E. 3883 3458A STEI�ART, Frank G. 3336 3450C PAULSON , s. Jean 3874 4519 PAYNE , Judd A. 3200 2214A PIETRASIEWICZ , Val J. 3723 2236M STOEBE , Suzanne M. 3562 3413 PO KEMPNER , Margo 3825 3422M STONEHOCKER , Garth H. 3756 4516D STONER , Ru ssell B. 3572 3009 POMPER , William J. 3730 2236 �1 PRATT , Lauren E. 3826 2234B TEITELBAUM , Jeremy T. 4302 4516C TETERS , Larry R. 4430 3419M THOMPSON , Moody c. , Jr . 3508 3442A RANDELL , Holly L. 3786 45l5 THOMPSON , Ray E. 3352 2-0123 REASONER, Rita K. 3184 4522A TVETEN , Lowe ll H. 3621 3445 REH�I , Eric C. 3364 4516E ROSICH , Rayner K. 3109 3415 RUSH , Charles M. 3460 34ll UTLAUT, William F. 3500 3020 RUSSELL , Deborah J. 3358 3450 VAN STORY , Carol B. 3267 3017 RUSSELL , Jane L. 3588 4525 VAUGHAN , Margo S. 4129 4516B VIOLETTE , Edmond J. 3703 3446A VOGLER , Lewis E. 3668 3450 SANCHEZ, Patricia A. 4166 2-0321 SANDERS , Frank H. 32ll 2222 SARRAZ IN, David B. 3562 3413 WALLER , Freda L. 3618 2223 SEITZ , Neal B. 3106 2214 WALTERS , William D. 4414 3019 SEXTON , Alma B. 3883 3449 WARNER, Billie D. 4496 3454B WASHBURN , James s. 3798 3413M WAS SON , Gene E. 3584 3430 SHELTON , Lenora J. 3572 3011 SKERJANEC , Richard E. 3l57 2230 SMILLEY , John D. 4218 2222M WATTERSON , Clark c. 3536 2241 SMITH , Dean 3661 2237 IVELLS , Paul I. 4368 2235 SPAULDING , Arthur D. 4201 2222A NIEDER , Bernard 3484 3014 IVILLIAMS , John G. 3594 2210 WILSON , Debra R. 3634 3419 I�ORTENDYKE , David R. 4241 2233 158 ANNEX IV ITS PUBLICATIONS - FISCAL YEAR 1979 Agy , v. L. (1979) , Perspective on the prediction of Dougherty , H. T. , and c. M. Rush (1979) , Propaga auroral absorption , Proc . of AGARD Symposium of tional aspects of allocation and frequency the Electromagnetic Wave Propagation Panel, sharing , Proc . of ITU Regional Seminar Prepara Li sbon , Portugal , May 28-June 1, pp . 19-1 - 19-15. tory to WARC 1979, Panama , March 12-23, pp . 1-17 , Agy , v. L. , G. w. Haydon , C. M. Me llecker , and C. M. Dutton , E. J. (1978) , Earth-space attenuation pre Rush (1979) , FY 78 progress report to Inter dictions for geostationary satellite links in national Commun ications Agency , Voice of Amer ica , the U.S.A, , NTIA Report 78-10 , October , 48 pp . Contract IA-18212-23 , NTIA Technical Memorandum (NTIS Access . No . PB 28984 1/AS) . 79-8, January , 20 pp . .Dutton , E. J. , and H. T. Dougherty (19 79) , Year-to Agy , v. L. , G. w. Haydon , C. M. Me llecker , and c. M. year variability of rainfall for microwave Rush (1979) , Annex to FY 78 progress report to app lications in the U.S.A. , IEEE Trans. Commun . International Communications Agency , Voice of COM-27 , No . 5, May , pp . 829-832. America , Contract IA-18212-23, NTIA Technical Memorandum 79-10, February, 60 pp . Espeland , R. H. , E. J. Violette , and M. C. Thompson, Jr . (1979) , An assessment of government radio Akima , H. (1978) , A note on measures of voice trans frequency assignments in the 3.0-10 .0 GHz band mission performance used by the CCIR, IEEE Trans. with considerations for applications above Commun . COM-26 , No . 10, October , pp . 1478-1480. 10 GHz , NTIA Technical Memorandum 79-13, May , 51 pp. Akima , H. (1979) , Remark on Algorithm 526, Bivariate interpolation and smooth surface fitting for FitzGerrell, R.G., R.D. Jennings , and J.R. Juroshek irregularly distributed data points { El} , ACM (1979) , Television receiving antenna system Trans . Math. Software 5, No . 2, June , - component measurements , NTIA Report 79-2�, pp. 242-243. June , 115 pp . (NTIS Access . No . Not Yet Available), Akima , H. , P. M. McManamon , and P. I. We lls (1978) , Gallawa , R. L. (1978) , Dispersion characteristics of Fixed-satellite and broadcasting-satellite fiber systems at long wavelengths , Proc . of First service considerations for 1979 Gl�ARC planning, Fiber Optics and Communications Exposition , NTIA Special Publication 78-2, October, 102 pp. Chicago , IL, Sept . 6 - B,··pp . 159-161. Berry , L. A. (1978) , Measuring spectrum use , IHreless Gallawa , R. L. (1979) , Recent developments in optical Wo rld , December , pp . 43-46. waveguide commun ications , Pt . I: Optimum refrac tive index profiles for multimode fibers , Electro Berry , L. lA. (1979) , Probability of intermodulation Optical Systems Design , July , pp . 42-44; Pt . II : interference in an expanded CB service, NTIA Renewed interest in monomode fibers, Sept . Technical Memorandum 79-15, July , 20 pp. Gallawa , R. L. (1979) , Problems , results, and availa Berry , L. A. , and E. J. Haakinson (1978) , Spectrum bility of a recent interlaboratory effort on an efficiency for multiple independent spread optical waveguide communications glossary , Proc . spectrum land mobile radio systems , NTIA Report of Second Fiber Optics and Communications Expo 78-11, November , 65 pp. (NTIS Access. No . sition, Chicago , IL , Sept . 5-7 . PB 291539/AS) . Hause , L. G. , and D. R. Wortendyke (1979) , Automated Chilton , C. J. (1979) , \�ave interaction observations digital system engineering model, NTIA Report of ionospheric modification in the D-region, 79-18 , March, 98 pp . (NTIS Access No . PB 2949�/AS) , NTIA Technical Memorandum 79-4, January , 35 pp . Haydon , G. W. , C. M. Rush , and L. R. Teters (1979) , Cho , S. H. , and J. R. Wait (1978) , Analysis of micro Theoretical feasibility of digital communication wave ducting in an inhomogeneous troposphere , over ocean areas by high frequency radio , NTIA Pure Appl. Geophys . 116, No . 6, pp. 1118-1142. Technical Memorandum 79-17, July , 46 pp . Collins, J. T. , and F. K. Steele (1979) , An addition Hildebrandt , T. H. (1979), A flowchart drafting tool al catalog of programs and data for 100 MHz - using a calculator-controlled plotter , NTIA 100 GHz radio system predictions , NTIA Report Technical Memorandum 79-3, January , 24 pp . 79-15, January , 48 pp . (NTIS Access . No . PB 293366/AS ) , Hill, D. A. (1979) , Electromagnetic wave propagation along a pair of rectangular bonded wire· meshes, Crombie , D. D. (1979) , Comparison of measured and IEEE Trans. Electromagnetic Compatibility ---EMC-21, predicted signal strengths of nighttime medium No . 2, May, pp. 114-122·, frequency signals in the USA, IEEE Trans. Broad casting BC-25, No . 3, September , pp . 86-89. Hill, D. A. , and J. R. l�a it (1978) , Electromagnetic basis of drill-rod telemetry , Electron . Letters Crow , E. L. (1979) , Approximate confidence intervals 14, No . 17 , August , pp . 532-533. for a proportion from Markov dependent trials, Commun . Statist.-Simula . Computa ., B8 (1) , Hill, D. A. , and J. R. Wait (1978) , Theory of electro pp . 1-24. magnetic methods for nondestructive testing of wire ropes , Proc . of Fourth West Virginia Univer Crow , E. L. (1979) , Statistical methods for estimat sity Conf . on Coal Hine Electrotechnology , ing time and rate parameters of digital communi August 2-4 , pp . 16-1 - 16-13. cation systems, NTIA Report 79-21, June , 41 pp. (NTIS Access . No . Not Yet Available). Hill, D. A., and J. R. Wait (1978) , Bandwidth of a leaky coaxial cable in a circular tunne l, IEEE Crow , E. L. , and M. J. Miles (1979) , Validation of Trans . Commun . COM-26 , No . 11 , November , --- estimators of a proportion from Markov dependent pp . 1765-1771 . trials ; Commun . Statist .-Simu la. Computa ., B8 (1) , pp . 25-52 . Hill , D. A. , and J. R. Wait (1978) , Electromagnetic surface-wave propagation over a rectangular-bonded Dougherty , H. T. (1978) , Atmo spheric limitations on wire mesh, IEEE Trans . Electromagnetic Compati telecommunication system performance - recent bility EMC-20, No . 4, November, pp . 488-494. advances , Proc . National Telecommunications Con ference , Birmingham , Alabama, December 4 & 5, Hill, D. A. , and J. R. Wait (1978) , Excitation of the �. pp . 18 .1.1 - 18 .1.5. Zenneck surface wave by a vertical aperture , Radio Sci. 13, No . 6, November-December, pp . 969-977-;- 159 Hill, D. A. , and J. R. Wait (1979) , Electromagnetic McManamon , P. M. (1979) , A hybrid sate llite for field perturbation by an internal void in a con Pacific nations using sma ll earth stations , Proc . ducting cylinder excited by a wire loop , Appl. of Pacific Telecommun ications Conference , Phys . 18, pp . 141-147. Honolulu, Hawaii, January 8 & 9, pp . 4B-24 - 4B-33 . Hill , D. A. , and J. R. Wait (1979) , Comparison of loop and dipole antennas in leaky feeder com Nesenbergs, M. (1979) , A hybrid of Erlang B and C munication systems , Proc . of AGARD Symposium of formu las and its applications , IEEE Trans. the Electromagnetic Wave Propagation Panel , · commun . COM-27 , No . 1, January , pp . 59-68 . Lisbon , Portugal, May 28-June 1, pp . 44-1 - 44-9. ·Nesenbergs , M. (1979) , Potential use of HF data Hubbard , R. W. (1979) , Investigation of digital transmission for oceanic ATC improvement , NTIA microwave commun ications in a strong meteorolog Technical Memorandum 79-14, May , 41 pp . ical ducting environment, NTIA Report 79-24 , August, 96 pp . (NTIS Access . No . Not Yet Ott , R. H. (1979) , Ground wave propagation over Available) . irregular , inhomogeneous terrain : Comparisons of calculations and measurements at frequencies from Hubbard , R. w. , and R. L. Gallawa (1978) , Design 121 kHz to 50 MHz , Proc . of AGARD Specialists handbook for optical fiber systems , u.s. Army Mtg . on Terrain Profiles and Contours in EM Communications-Electronics Engineering Instal Propagation , Spatind , Norway , Sept . 10-14 , lation Agency report CCC-CED-XES-78-01, August, pp. 6-1 - 6-8 . 265 pp . Ott , R. H. (1979) , Theories of ground wave propaga Hull , J. A. (1979) , Fiber optic communications and tion over mixed paths , Proc . of AGARD Specialists the Federal government , Proc . of Second Fiber Mtg . on Terrain Profiles and Contours in EM Prop Optics and Communications Exposition , Chicago, agation , Spatind , Norway , Sept . 10-14 , IL, Sept. 5-7 . pp . 8-1 - 8-7 . Hull , J. A. , R. L. Gallawa , and L. R. Bloom (1979) , Ott , R. H. , E. L. Morrison , and W. B. Grant (1979) , The development of fiber optic communications , Antenna patterns for the solar power satellite , Proc . of ICC '79, Boston , MA, June 10-13 , NTIA Technical Memorandum 79-5 , January , 24 pp . pp . 10. 3.1 - 10.3.3. Dtt , R. H., M. c. Thompson , Jr. , E. J. Violette , and Hull, J. A. , J. M. Harman , M. N. Olson , and H. D. K. c. Allen (1978) , Experimental and theoretical Hunt (1979) , Emergency Medical Services communi assessment of multipath effects on QPSK , IEEE cations system technical planning guide , NTIA Trans. Commun . COM-26 , No . 10 , October , --- Special Publication 79-3, March, 214 pp . pp . 1475-1477 . (SupDocs Order No . 003-000-00547-0). Ott , R. H. , L. E. Vogler , and G. A. Hufford (1979) , Johnson , M. E. , and G. D. Gierhart (1979) , Comparison Groundwave propagation over irregular inhomogen of measured data with IF-77 propagation model eous terrain : Comparisons of calculations and predictions , U.S. Dept . of Transportation Report measurements , IEEE Trans . Ant . Prop . AP -27 , No . 2, ----- FAA-RD- 79-9 , August , 444 pp . March , pp. 284- 286. Juroshek , J. R. (1979) , A compatibility analysis of Ott , R. H. , L. E. Vogler , and G. A. Hufford (1979) , spread-spectrum and FM land mobile radio systems , Ground wave propagation over irregular , inhomo NTIA Report 79-23, August , 80 pp. (NTIS Access . geneous terrain : Comparisons of calculations and No . Not Yet Available) . measurements , NTIA Report 79-20, May , 137 pp . (NTIS Access . No . Not Yet Ava ilable ). Kissick , W. A. , and J. E. Adams (197g) , The Kodiak site study , NTIA Technical Memorandum 79-11 , Rush , c. M. (1979) , Transionospheric radio propaga March , 83 pp . tion, NATO AGARD Lecture Series No . 99 : Aero space Propagation Media Modelling and Prediction Kissick , W. A. , E. J. Haakinson , and G. H. Stone Schemes for Modern Commun ications , Navigation , hocker (1978) , Measurements of LF and MF radio and Surveillance Systems , May; Presented June 4-5 propagation over irregular , inhomogeneous terrain , in London , UK , and june 14-15 in Boulder , CO ; NTIA Report 78-12 , November , 171 pp . (NTIS pp . 4-1 ..: 4-28. Access. No . PB 291732/AS) . Schlafly , H. J. , R. E. Button , and B. L. Wormington Kissick , W. A. , and K. P. Spies (1979) , Alternatives (1 979) , The initial growth and expanding oppor to the AMVE R guards on 8, 12, & 16 MHz at San tunities of u.s. domestic satellite ser�ice , NTIA Juan and 8 MHz at Kodiak , NTIA Technical Memoran Contractor Report 79-3 , February , 158 dum 79-12 , May , 108 pp . PP�· Skerjanec , R. E. , and R. 1'1 . Hubbard (1979) , Aircraft Liebe , H. J. (1979) , Millimeter wave attenuation in obstruction of microwave links , NTIA Report 79-14 , moist air , Proc . of Army Conf . on Millimeter Wave January , 68 pp . (NTIS Access. No . PB 292372/AS) . Propagation , Huntsville, AL , March 20-22 . Spaulding , A. D. (1979) , Optimum threshold signal Liebe , H. J. , and D. D. Crombie (1979) , Estimates of detection in broadband impulsive noise emp loying maximum electric field strengths in the automo both time and spatial sampling , Proc . of 3rd bile environment , NTIA Report 79-16, February, Sympo sium and Technical Exposition on Electro 29 pp . (NTIS Access. No . PB 294819/AS) . magnetic Compatibility , Rotterdam , Netherlands, May 1-3, pp . 377-385 . Liebe , H. J. , and J. D. Hopponen (1978) , Atmospheric medium characterization and modelling of EHF Violette , E. J. , R. H. Espeland , M.C. Thompson , Jr . propagation in air , AGARD Conf . Proc . ---238, (1979) , An economic evaluation of systems and December , pp . 45-1 - 45-18. components for short path commun ication links above 10 GHz , NTIA Technical Memorandum 79-16, Liebe , H. J. , and R. K. Rosich (1979) , Modelling of July , 31 pp . EHF propagation in clear air, Proc . of 1979 IEEE Region V Annual Conference on Space Instrumenta Wa it, J. R. , and D. A. Hill (1979) , Theory of trans tion for Atmospheric Observation, El Paso , TX , mission of electromagnetic waves along a drill Ap ril 3-5 , pp . 6-20 . rod in conducting rock, IEEE Trans . Geosci. Electron . GE-17 , No . 2, Apri l, pp . 21-24 . Linfield, R. F. (1979) , Control signaling in a mili tary switching environment, NTIA Report 79-13 , January , 250 pp . (NTIS Access . No . PB 292377/AS) . 160 Wait, J. R. , and D. A. Hill (1979) , Excitation of ADDENDUM : the H.F. surface wave by vertical and horizontal apertures , Proc . of AGARD/NATO Conference Dougherty , H. T. , and C. M. Rush (1979) , Propaga "Special Topics in H.F. Propagation ," Lisbon , tional aspects of frequency allocation and Portugal , May , pp. 41-1 - 41- 10. frequency sharing , NTIA Technical Memorandum 79-19 , September, 24 pp . Washburn , J. S., R. A. McLean, S. J. Coleman , W. M. We lch , and D. c. Hyovalti (1979) , Operator 's Hanson , A. G. , L. R. Bloom , G. w. Day , R. L. Ga llawa , guide to the Electromagnetic Radiation Hazards E. M. Gray , and M. Young (1979) , Optical wave Scenario , NTIA Technical Memorandum 79-7, guide communications glossary , NTIA Special January , 127 pp . Publication 79-4 , September , 73 pp . (NTIS Acces·s . No . Not Yet Available) . Watterson , C. c. (1979) , An adaptive receiver filter for interference suppression in digital spread spectrum radio systems (U) , NTIA Technical Memo randum 79-9C, February, 142 pp . Wieder , B. , R. H. Espeland , L. R. Teters , and J. S. Washburn (1978) , An application of holographic principles to locating multipath scatterers in LF navigation systems , Proc . of Seventh Annual Technical Symposium of The Wild Goose Association , New Orleans , LA , October 18-20, pp. 170-175 . Wortendyke , D. R. , and T. H. Hildebrandt (1979) , Received signal level (RSL) measurements and analysis with a desk-top computer , NTIA Report 79-17, February , 160 pp . (NTIS Access . No . PB 294820/AS) . Wortendyke , D. R. (1979) , Proj ect Green Thumb , Proc. of Fourth West Coast Computer Faire, San Francisco , CA, May 11-13, pp . 90-91 . AVAILABILITY OF PUBLICATIONS - NTIA Reports , Special Publications, and Contractor Reports are available from the National Technical Information Service . Order by accession number shown in publications listing . Technical Memoranda are not generally available , but additional information may be secured by contacting the author. Requests for copies of journal articles should be addressed to the journal. 161 ANNEX V GENERAL AND HISTORICAL INFORMAT ION OF ITS The Institute for Telecommunication Sci was completed in 1954, during which year ences , largest component of the National President Eisenhower dedicated the NBS Telecommunications and Information Admini Radio Building . The Radio Standards pro stration, is located at the Boulder Lab gram left CRPL at the time of the move to oratories of the Department of Commerce Boulder , and has pursued a parallel exist and has (as of Sept . 30 , 1978) a full-time ence at Boulder in NBS since that time . permanent staff of 100 and other staff of 45. In FY 1978 , its support consisted of In 1954 , CRPL consisted of two research $1.9 million of direct funding from Com divisions : Radio Propagation Physics and merce and $7.5 million in work sponsored Radio Propagation Engineering . The Radio by other Federal agencies . Systems Division was formed in 1959 . In 1960, the Upper Atmosphere and Space Phys The Boulder Laboratories include research ics Division and the Ionosphere Research and engineering components of the National and Propagation Division were formed from Bureau of Standards , the National Oceanic the Radio Propagation Physics Division . and Atmospheric Administration, and the In 1962, CRPL received a full-time Direc National Telecommunications and Informa tor , Dr. C. Gordon Little . In 1965 , Dr . tion Administration . Common administra H. Herbert Holloman , first Assistant Sec tive services are the rule in the Boulder retary for Science and Technology in Com Laboratories. The Radio Building , which merce , implemented a decision to unify houses ITS , is on the National Bureau of geophysics in Commerce with the creation Standards campus at 325 Broadway . In of the Environmental Science Services addition to ITS, the National Telecommuni Administration (ESSA) , made up of the cations and Information Administration Weather Bureau , the Coast and Geodetic also has its Boulder Division of the Survey , and the Central Radio Propagation Office of Policy Analysis and Development Laboratory . At that time , the CRPL was located in the 30th Street Building off renamed the Institute for Telecommunica Baseline Road in Boulder. tion Sciences and Aeronomy (ITSA) . In 1967 , the Institute for Telecommunication The following brief history shows its NBS Sciences came into being . It contained beginnings . The Radio Section of the the telecommunications-oriented activities National Bureau of Standards was founded of ITSA . Dr . E. K� Smith served as an prior to World War I, and played a major interim Director for one year and wa s role in the evolution of our understanding followed by R. C. Kirby who was Director of radio propagation . Dr. J.H. Dellinger , for the ensuing three years. its director for most of the period up until World War II, was strongly convinced Meanwhile , in Washington , major attention of the importance of research and gave it was being given to the organization of practical application as first Chairman of telecommunications in the Federal ' estab the Study Group on Ionosphere Propagation lishment, and the Department of Commerce in the CCIR. established an Office of Telecommunications in 1967 . Reorganization Plan No . 1 of During World War II, the Interservice 1970 and Executive Order 11556 established Radio Propagation Laboratory (IRPL) was the Office of Telecommunications Policy organized at the National Bureau of Stand (OTP) in the Executive Office of the Pres ards, under the direction of Dr . Dellinger . ident , and assigned additional responsi His group provided a common focus for bilities to the Secretary of Commerce in military needs in propagation during the support of OTP . To meet these responsi war . In 1946, the Central Radio Propaga bilities , the Office of Telecommunications tion Laboratory (CRPL) was established , (OT) was given expanded responsibilities and in its early years had direct ties on September 20, 1970, and ITS , along with with the Defense Department; for example, its programs , property , personnel, and senior officials of DoD would appear be fiscal resources was transferred to OT . fore Congress to defend the CRPL budget . In 1949, Congressional concern for the In 1971, Douglass D. Crombie became Dir vulnerability of government laboratories ector of ITS . ITS has shifted from its located in Washington , D.C. , and the strong emphasis on radio wave propagation crowding of the NBS Connecticut Avenue and antennas since 1970, in the direction campus made it advisable for the radio of applications in spectrum management and research work to be taken elsewhere . in telecommunication systems. Three sites, one in California, one in In March 1978, .President Carter signed Colorado , and one in Illino is , were con Executive Order 12046 which established sidered , and Boulder , Colorado , wa s selec the National telecommunication s and Infor ted . The first group from CRPL , which at mation Administration and merged some of that time included radio standards work , the functions of the Office of Telecom moved to Colorado in 1951, and the move munications Policy with those of the Office 163 of Telecommunications in the new agency . The Department of Defense has long been ITS was assigned the responsibility of the primary source of advanced technology . managing the tele communications technology At the present time , the largest part of research programs of NTIA and providing the other agency sponsorship of ITS comes research support to other elements of NTIA from needs of the Department of Defense. as well as other agenc ies on a reimburs However, there is also a clear need for able basis . Among other assigned tasks , relevance to national goals on the civil the Institute was to remain " ...the ian side of the Federal establishment. central Federal Government laboratories ITS is therefore moving to increase its for research on transmission of radio work with the civil side of the Federal waves ." Government . The agencies in the civilian sector are frequently also in the high ITS and its predecessor organizations have technology area ; for example, the FAA and always played a strong role in pertinent NASA , for which ITS has done , and contin scientific (URS I ), professional (IEEE) , ues , very important work in navigation , national (IRAC) , and international (CCIR) collision avoidance , satellite communica governmental activities . The Director of tions , and related work . CCIR from 1966 to 1974 was Jack W. Herb streit, a former Deputy Director of CRPL and ITSA, and the current CCIR Director is Richard c. Kirby , formerly Director of ITS . At the present time , the U.S. preparatory work for three of the eleven Study Groups of CCIR is directed by members of ITS (U.S. Study Groups 1, 3, and 5) , and staff members of ITS participate in many of the other Study Groups . ITS actively supports the Interdepartment Radio Advisory Commit tee (IRAC) , and the Chairmen of its Stand ards Working Group (J.A. Hull) and the Propagation Working Group (W.F. Utlaut) of the Technical Subcommittee are members of ITS management . The work which ITS does for other agencies in the government derives its legal authorities from 15 u.s.c. 272 (e) "Advi sory Services to Government Agencies on Scientific and Technical Problems " and 15 u.s.c. 272 (f) "Invention and Development of Devices to Serve Special Needs of Government." As a matter of Federal pol icy, NTIA does not accept work more appropriately done by other non-government or government organizations. It is also a matter of policy that all sponsored work reinforce NTIA's overall program and that it be clear that other agencies , indus tries , or universities could not serve equally well or better. Within these policy guides, ITS aspires to being the Federal laboratory for research in telecommunications. It is clear that the government has a responsibility to pursue long-range studies in telecommuni cations which are not economically pr9fit able for industry . It is also clear that the government must have its own , inde pendent laboratories to assess the sig nificance of research conducted elsewhere . Towards these ends , ITS strives to ma in tain a knowledgeable staff that is working on the frontiers of technology and is in touch with the telecommun ications problems of the Federal Government . Its programs and future directions are succinctly given in the Foreword and Introduction of this report by ITS Director D.D. Crombie . U. S. GOVERNMENT PR INTING OFF ICE 1979 - 68 1-366/75 Reg . 8 164 INSTITUTE for TELECOMMUNICATION SCIENCES 01rector Douglass 0 Cromb1 e Secretary · Beverle J G1bson X 4215 Deputy 01rector Or William F Utlaut Secretary · Marc•a L. Ge1ss•nger X 3500 CONSULTANT ADMINISTRATION Dr. James R. Wait X 6471 �------4------� William D. Walters X 4414 PUBLIC TECHNICAL & INFORMATION OFFICE Russell B. Stoner X 35 72 _l l I I DIVISION 1 DIVISION 2 DIVISION 3 DIVISION 4 SPECTRUM UTILIZATION SYSTEM TECHNOLOGY STANDARDS APPLIED ELECTROMAGNETIC SCIENCE ADVANCED COMMUNICATION NETW ORKS & Associate Director John P. Murray · Associate Director · Joseph A. Hull Associate Director · Donald l. lucas Associate Director . Dr. Peter M . McManamon Secretary Elizabeth McCoy N . Secretary · Jean R. Mallard Secretary · Patricia Sanchez · l. X 4162 Secretary · Marylyn Olson X 4136 X 3821 X 4166 Consultant George W. Haydon X3583 SPECTRUM ANALYSIS. EVALUATION OF NEW EM PROPAGATION COMMUNICATIONS MODELING SERVICES �RESEARCH ANALYSIS PROTECTION � & �TECHNOLOGY DEVELOPMENTS & I-- Louis R. Bloom. Dr. Moody C. Thompson . Jr. Jean E. Adams. X 4301 X 3485 X 3508 EM ENVIRONMENT 1-- SYSTEMS PERFORMANCE ADVANCED COMMUNICATION � SWITCHED NETWORKS CHARACTERIZATION CRITERIA TECHNOLOGY APPLICATIONS I-- 1-- & Robert J . Matheson. X 3293 Dr. Harvey Gates. X 3589 William B. Grant. X 3729 SPECTRUM PLANNING '--- PROPAGATION PREDICTIONS '--- SPECIALIZED L--- '---- SYSTEMS REQUIREMENTS & METHODOLOGY DEFINITION MODEL DEVELOPMENT NETWORKS Dr. George A. Hufford. X 345 7 Ernest L. Morrison. X 4215 Dr. Charles M. Rush, X 3460