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WWVB: a Half Century of Delivering Accurate Frequency and Time by Radio
Volume 119 (2014) http://dx.doi.org/10.6028/jres.119.004 Journal of Research of the National Institute of Standards and Technology WWVB: A Half Century of Delivering Accurate Frequency and Time by Radio Michael A. Lombardi and Glenn K. Nelson National Institute of Standards and Technology, Boulder, CO 80305 [email protected] [email protected] In commemoration of its 50th anniversary of broadcasting from Fort Collins, Colorado, this paper provides a history of the National Institute of Standards and Technology (NIST) radio station WWVB. The narrative describes the evolution of the station, from its origins as a source of standard frequency, to its current role as the source of time-of-day synchronization for many millions of radio controlled clocks. Key words: broadcasting; frequency; radio; standards; time. Accepted: February 26, 2014 Published: March 12, 2014 http://dx.doi.org/10.6028/jres.119.004 1. Introduction NIST radio station WWVB, which today serves as the synchronization source for tens of millions of radio controlled clocks, began operation from its present location near Fort Collins, Colorado at 0 hours, 0 minutes Universal Time on July 5, 1963. Thus, the year 2013 marked the station’s 50th anniversary, a half century of delivering frequency and time signals referenced to the national standard to the United States public. One of the best known and most widely used measurement services provided by the U. S. government, WWVB has spanned and survived numerous technological eras. Based on technology that was already mature and well established when the station began broadcasting in 1963, WWVB later benefitted from the miniaturization of electronics and the advent of the microprocessor, which made low cost radio controlled clocks possible that would work indoors. -
Measurement of Time
Measurement of Time M.Y. ANAND, B.A. KAGALI* Department of Physics, Bangalore University, Bangalore 560056 *email: [email protected] ABSTRACT Time was historically measured using the periodic motions of the sun and stars. Various types of sun clocks were devised in Egypt, Greece and Europe. Different types of water clocks were assembled with ever greater accuracy. Only in the seventeenth century did the mechanical clock with pendulums and springs appeared. Accurate quartz clocks and atomic clocks were developed in the first half of the twentieth century. Now we have clocks that have better than microsecond accuracy. This article gives a brief account of all these topics. Keywords: Sun clocks, Water clocks, Mechanical clocks, Quartz clocks, Atomic clocks, World Time, Indian Standard time We all know intuitively what time is. It can be civilizations relied upon the apparent motion of roughly equated with change or motions. From these bodies through the sky to determine the very beginning man has been interested in seasons, months, and years. understanding and measuring time. More We know little about the details of recently, he has been looking for ways to limit timekeeping in prehistoric eras, but we find the “damaging” effects of time and going that in every culture, some people were backward in time! preoccupied with measuring and recording the Celestial bodies—the Sun, Moon, planets, passage of time. Ice-age hunters in Europe over and stars—have provided us a reference for 20,000 years ago scratched lines and gouged measuring the passage of time. Ancient holes in sticks and bones, possibly counting the Physics Education • January − March 2007 277 days between phases of the moon. -
Reception of Low Frequency Time Signals
Reprinted from I-This reDort show: the Dossibilitks of clock svnchronization using time signals I 9 transmitted at low frequencies. The study was madr by obsirvins pulses Vol. 6, NO. 9, pp 13-21 emitted by HBC (75 kHr) in Switxerland and by WWVB (60 kHr) in tha United States. (September 1968), The results show that the low frequencies are preferable to the very low frequencies. Measurementi show that by carefully selecting a point on the decay curve of the pulse it is possible at distances from 100 to 1000 kilo- meters to obtain time measurements with an accuracy of +40 microseconds. A comparison of the theoretical and experimental reiulb permib the study of propagation conditions and, further, shows the drsirability of transmitting I seconds pulses with fixed envelope shape. RECEPTION OF LOW FREQUENCY TIME SIGNALS DAVID H. ANDREWS P. E., Electronics Consultant* C. CHASLAIN, J. DePRlNS University of Brussels, Brussels, Belgium 1. INTRODUCTION parisons of atomic clocks, it does not suffice for clock For several years the phases of VLF and LF carriers synchronization (epoch setting). Presently, the most of standard frequency transmitters have been monitored accurate technique requires carrying portable atomic to compare atomic clock~.~,*,3 clocks between the laboratories to be synchronized. No matter what the accuracies of the various clocks may be, The 24-hour phase stability is excellent and allows periodic synchronization must be provided. Actually frequency calibrations to be made with an accuracy ap- the observed frequency deviation of 3 x 1o-l2 between proaching 1 x 10-11. It is well known that over a 24- cesium controlled oscillators amounts to a timing error hour period diurnal effects occur due to propagation of about 100T microseconds, where T, given in years, variations. -
Mini Quartz Clock Movements
Mini Quartz Clock Movements • 10 Year Warranty • Step Second Hand • Dimensions: 2-1/8"W x 2-1/8"H x 5/8"D • Runs on 1 "AA" Size Battery • American "I" Shaft - Diameter 5/16" • Free Set Of Hands and • Front Loading Hanger Mounting Hardware With • Accurate Within 2 Minutes A Year Each Clock Movement • Fits 3" Diameter Hole • Made in USA 1. Drill a 3/8" hole through the material you are working with and insert the movement. 2. Slide brass washer over shaft. 3. Attach dial mounting hex nut. 4. Gently press hour hand onto shaft at 12:00 position. 5. Place minute hand over shaft at 12:00 position. 6. Gently screw minute nut in place. 7. Press on second hand at 12:00 position. 8. Screw on cap nut if no second hand is used. Mini Movements Shaft Length Selecting the Proper Shaft Length Dials B A P r i c e E a c h P e r P k g O f Proper shaft length is important to ensure Stock# up to Thread Total 1 3 10 50 100 sufficient clearance when going through your dial Q-11 1/8" thick 3/16" 17/32" 4.95 4.23 4.45 3.80 4.25 3.63 3.95 3.38 3.75 3.21 board and when using a glass front on your clock. Q-12 1/4" thick 5/16" 5/8" 4.95 4.23 4.45 3.80 4.25 3.63 3.95 3.38 3.75 3.21 Overall Length (A) is measured from the tip of Q-13 3/8" thick 7/16" 3/4" 4.95 4.See23 4.4 website5 3.80 4.25 3for.63 3current.95 3.38 3.75 3.21 the hand shaft to the movement cast. -
Analog Clock Headway Movement FAQS
ANALOG CLOCK HEADWAY MOVEMENT FAQS The links below will work in most PDF viewers and link to the topic area by clicking the link. We recommend Adobe Reader version 10 or greater available at: http://get.adobe.com/reader CONTENTS Analog Clock Headway Movement FAQS .................................................................... 1 Batteries ............................................................................................................................. 2 Atomic Clock Factory Restart ...................................................................................... 2 Supported Time Zones .................................................................................................. 2 Time is Incorrect ............................................................................................................. 2 Clock is incorrect by Hours but minutes are correct .......................................... 3 Daylight Saving Time ..................................................................................................... 3 Manually Set Time ........................................................................................................... 3 How long will the battery last? .................................................................................. 3 Can I shut off the WWVB signal? .............................................................................. 3 Is there a booster antenna to receive the WWVB signal in a difficult location? ............................................................................................................................ -
77A71 Quartz Clock Movement Instructions
77A71 07/28/94 Quartz Clock Movement Instructions Product #3722X, 3723X The 3622X and 3723X quartz battery movements will operate The 3723X movement has a start-stop switch on the rear of the approximately 12 months on a fresh “C” alkaline battery. Insert the case. Both movements feature a hand set knob on the rear of the battery with positive end to your left as movement is held upright case. Telephone time recordings are generally adequate for setting looking from the rear. the time. The 3722X and 3723X movements should keep time to +/- To mount the movement, insert the handshaft through the center 10 seconds per month. hole in your dial and fasten with the brass nut and brass washer. Be sure to use a fresh battery when you install your clock. If you are The hanger and one or more shims (rubber washer) may be neces- not sure, have it tested on a battery testing device. Do not attempt sary between the movement and the dial to control the distance that to disassemble the movement case for any kind of service. the handshaft protrudes through the dial. (See Diagram A) The adjustable pendulum on the 3722X adjustable pendulum Press the hour hand onto its shaft, making sure it does not rub movement has no bearing on the time keeping of the movement against the dial. The minute hand fits onto the threaded “I” shaft itself and can be adjusted by “breaking” the brass rod at the scored and is held by a small nut. The second hand (optional) may now be lines and then replacing the brass bob. -
NIST Time and Frequency Services (NIST Special Publication 432)
Time & Freq Sp Publication A 2/13/02 5:24 PM Page 1 NIST Special Publication 432, 2002 Edition NIST Time and Frequency Services Michael A. Lombardi Time & Freq Sp Publication A 2/13/02 5:24 PM Page 2 Time & Freq Sp Publication A 4/22/03 1:32 PM Page 3 NIST Special Publication 432 (Minor text revisions made in April 2003) NIST Time and Frequency Services Michael A. Lombardi Time and Frequency Division Physics Laboratory (Supersedes NIST Special Publication 432, dated June 1991) January 2002 U.S. DEPARTMENT OF COMMERCE Donald L. Evans, Secretary TECHNOLOGY ADMINISTRATION Phillip J. Bond, Under Secretary for Technology NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY Arden L. Bement, Jr., Director Time & Freq Sp Publication A 2/13/02 5:24 PM Page 4 Certain commercial entities, equipment, or materials may be identified in this document in order to describe an experimental procedure or concept adequately. Such identification is not intended to imply recommendation or endorsement by the National Institute of Standards and Technology, nor is it intended to imply that the entities, materials, or equipment are necessarily the best available for the purpose. NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY SPECIAL PUBLICATION 432 (SUPERSEDES NIST SPECIAL PUBLICATION 432, DATED JUNE 1991) NATL. INST.STAND.TECHNOL. SPEC. PUBL. 432, 76 PAGES (JANUARY 2002) CODEN: NSPUE2 U.S. GOVERNMENT PRINTING OFFICE WASHINGTON: 2002 For sale by the Superintendent of Documents, U.S. Government Printing Office Website: bookstore.gpo.gov Phone: (202) 512-1800 Fax: (202) -
Time Signal Stations 1By Michael A
122 Time Signal Stations 1By Michael A. Lombardi I occasionally talk to people who can’t believe that some radio stations exist solely to transmit accurate time. While they wouldn’t poke fun at the Weather Channel or even a radio station that plays nothing but Garth Brooks records (imagine that), people often make jokes about time signal stations. They’ll ask “Doesn’t the programming get a little boring?” or “How does the announcer stay awake?” There have even been parodies of time signal stations. A recent Internet spoof of WWV contained zingers like “we’ll be back with the time on WWV in just a minute, but first, here’s another minute”. An episode of the animated Power Puff Girls joined in the fun with a skit featuring a TV announcer named Sonny Dial who does promos for upcoming time announcements -- “Welcome to the Time Channel where we give you up-to- the-minute time, twenty-four hours a day. Up next, the current time!” Of course, after the laughter dies down, we all realize the importance of keeping accurate time. We live in the era of Internet FAQs [frequently asked questions], but the most frequently asked question in the real world is still “What time is it?” You might be surprised to learn that time signal stations have been answering this question for more than 100 years, making the transmission of time one of radio’s first applications, and still one of the most important. Today, you can buy inexpensive radio controlled clocks that never need to be set, and some of us wear them on our wrists. -
Radio Navigational Aids
RADIO NAVIGATIONAL AIDS Publication No. 117 2014 Edition Prepared and published by the NATIONAL GEOSPATIAL-INTELLIGENCE AGENCY Springfield, VA © COPYRIGHT 2014 BY THE UNITED STATES GOVERNMENT NO COPYRIGHT CLAIMED UNDER TITLE 17 U.S.C. WARNING ON USE OF FLOATING AIDS TO NAVIGATION TO FIX A NAVIGATIONAL POSITION The aids to navigation depicted on charts comprise a system consisting of fixed and floating aids with varying degrees of reliability. Therefore, prudent mariners will not rely solely on any single aid to navigation, particularly a floating aid. The buoy symbol is used to indicate the approximate position of the buoy body and the sinker which secures the buoy to the seabed. The approximate position is used because of practical limitations in positioning and maintaining buoys and their sinkers in precise geographical locations. These limitations include, but are not limited to, inherent imprecisions in position fixing methods, prevailing atmospheric and sea conditions, the slope of and the material making up the seabed, the fact that buoys are moored to sinkers by varying lengths of chain, and the fact that buoy and/or sinker positions are not under continuous surveillance but are normally checked only during periodic maintenance visits which often occur more than a year apart. The position of the buoy body can be expected to shift inside and outside the charting symbol due to the forces of nature. The mariner is also cautioned that buoys are liable to be carried away, shifted, capsized, sunk, etc. Lighted buoys may be extinguished or sound signals may not function as the result of ice or other natural causes, collisions, or other accidents. -
STANDARD FREQUENCIES and TIME SIGNALS (Question ITU-R 106/7) (1992-1994-1995) Rec
Rec. ITU-R TF.768-2 1 SYSTEMS FOR DISSEMINATION AND COMPARISON RECOMMENDATION ITU-R TF.768-2 STANDARD FREQUENCIES AND TIME SIGNALS (Question ITU-R 106/7) (1992-1994-1995) Rec. ITU-R TF.768-2 The ITU Radiocommunication Assembly, considering a) the continuing need in all parts of the world for readily available standard frequency and time reference signals that are internationally coordinated; b) the advantages offered by radio broadcasts of standard time and frequency signals in terms of wide coverage, ease and reliability of reception, achievable level of accuracy as received, and the wide availability of relatively inexpensive receiving equipment; c) that Article 33 of the Radio Regulations (RR) is considering the coordination of the establishment and operation of services of standard-frequency and time-signal dissemination on a worldwide basis; d) that a number of stations are now regularly emitting standard frequencies and time signals in the bands allocated by this Conference and that additional stations provide similar services using other frequency bands; e) that these services operate in accordance with Recommendation ITU-R TF.460 which establishes the internationally coordinated UTC time system; f) that other broadcasts exist which, although designed primarily for other functions such as navigation or communications, emit highly stabilized carrier frequencies and/or precise time signals that can be very useful in time and frequency applications, recommends 1 that, for applications requiring stable and accurate time and frequency reference signals that are traceable to the internationally coordinated UTC system, serious consideration be given to the use of one or more of the broadcast services listed and described in Annex 1; 2 that administrations responsible for the various broadcast services included in Annex 2 make every effort to update the information given whenever changes occur. -
Time and Frequency Users' Manual
,>'.)*• r>rJfl HKra mitt* >\ « i If I * I IT I . Ip I * .aference nbs Publi- cations / % ^m \ NBS TECHNICAL NOTE 695 U.S. DEPARTMENT OF COMMERCE/National Bureau of Standards Time and Frequency Users' Manual 100 .U5753 No. 695 1977 NATIONAL BUREAU OF STANDARDS 1 The National Bureau of Standards was established by an act of Congress March 3, 1901. The Bureau's overall goal is to strengthen and advance the Nation's science and technology and facilitate their effective application for public benefit To this end, the Bureau conducts research and provides: (1) a basis for the Nation's physical measurement system, (2) scientific and technological services for industry and government, a technical (3) basis for equity in trade, and (4) technical services to pro- mote public safety. The Bureau consists of the Institute for Basic Standards, the Institute for Materials Research the Institute for Applied Technology, the Institute for Computer Sciences and Technology, the Office for Information Programs, and the Office of Experimental Technology Incentives Program. THE INSTITUTE FOR BASIC STANDARDS provides the central basis within the United States of a complete and consist- ent system of physical measurement; coordinates that system with measurement systems of other nations; and furnishes essen- tial services leading to accurate and uniform physical measurements throughout the Nation's scientific community, industry, and commerce. The Institute consists of the Office of Measurement Services, and the following center and divisions: Applied Mathematics -
Spectracom 8163 WWVB Receiver/Comparator
SPECTRACOM CORPORATION 320 N. Washington Street Rochester, New York 14625 WARRANTY REGISTRATION Dear Customer , Spectracorn occasionally contacts customers regarding our products. We must know to whom we should send manual updates, change notices, and new product information. Because people sometimes change job assignments, we request department, mail station, and title infor- mation to ensure that correspondence in future years will reach either the user of our products or 11isJher supervisor. In f i 1 ling out the registrat ion, please use the tit lelmail station/departrnent of the supervisor most interested in keeping the equipment and its dacumen- tat ion up-to-date. Thank you. E!ame Title Department Mail Stop Company Model Murnber Address Serial No. City Date installed State Zip Phone Ext . Remarks : (Problems , Suggen ions , etc .I CERTIFICATE OF TRACEABILITY SPECTRACOM CORPORATION hereby certifies that its Model 81 63 N8S Frequency Standard Receiver provides direct traceability to the National Bureau of Standards reference frequency as transmitted by station WWVB in Fort Collins, Colorado, with carrier frequency of 60 KHz. Automatic verification is provided by the station-identifying phase shift of 45' that appears on the carrier signal at 10 minutes after each hour, returning to normal five minutes later. This phase shift appears in the readout as an offset of about 2.1 micro- seconds on the front panel meter and on the strip chart recorder trace. When properly installed and maintained, the Model 8163 provides measurement accuracy and resolution as published in the equipment's instruct ion manual. SPECTWCOM CORPORATION WARRANTY Spectracorn corpora tion warrants to the original purchaser each new instrument to be f ree from defects in material and workmanship for a period of one year after shipment.