Time & Frequency

Bulletin

No. 384 November 1989

(NISTIR 89-3910-11)

/

NIST TIME & FREQUENCY BULLETIN

(Supersedes No. 383 October 1989)

NO. 384 NOVEMBER 1989

1. GENERAL BACKGROUND INFORMATION 1

2. TIME SCALE INFORMATION 1

International Timing Center comparisons via GPS common-view 2

3. UT1 CORRECTIONS AND LEAP SECOND ADJUSTMENTS 2

4. PHASE DEVIATIONS FOR WWVB AND LORAN-C 3

5. GOES TIME CODE INFORMATION 4

6. BROADCAST OUTAGES OVER FIVE MINUTES AND WWVB PHASE PERTURBATIONS .... 4

7. NOTES ON NIST TIME SCALES AND PRIMARY STANDARDS 5

8. SPECIAL ANNOUNCEMENTS 7

This bulletin is published monthly. Address correspondence to:

Gwen E. Bennett, Editor

Time and Frequency Division

National Institute of Standards & Technology

325 Broadway

Boulder, CO 80303

(303) 497-3295

NOTE TO SUBSCRIBERS: Please include your address label (or a copy)

with any correspondence regarding this bulletin.
1. GENERAL BACKGROUND INFORMATION

ABBREVIATIONS AND ACRONYMS USED IN THIS BULLETIN

APL

BIH

CCIR - CRL

Cs

CSIRO - GOES - GPS

IEN

INPL - LORAN - MC

MJD

NIST - NPL

NRC

NOAA - OP

PTB

SIsvTA

TAI

TAO

TUG

US NO - UTC

VLF

VSL

John Hopkins University Applied Physics Laboratory

International Time Bureau, France

International Radio Consultative Committee

Communications Research Laboratories, Japan

Cesium standard

Commonwealth Scientific and Industrial Research Org

Geostationary Operational Environmental Satellite

Global Positioning System

National Institute of Electronics, Italy

National Physical Laboratory, Israel

Long Range Navigation

Master Clock

Modified Julian Date

National Institute of Standards & Technology

National Physical Laboratory, England

National Research Council, Canada

National Oceanic and Atmospheric Administration

Paris Observatory, France

Physical Technical Federal Laboratory, Germany

International System of Units

Space vehicle

Atomic Time

International Atomic Time

Tokyo Astronomical Observatory, Japan

Technical University of Graz, Austria

United States Naval Observatory

Coordinated Universal Time

very low frequency

Van Swinden Laboratory, Netherlands

anization, Australia

ns nanosecond

us - microsecond

ms millisecond

s second

min - minute

h hour

d day

2. TIME SCALE INFORMATION

The values listed below are based on data from the BIH, the USNO, and the NIST. The UTC - UTC(NIST) values are extrapolations since UTC is computed more than two months after the fact. The UTC(USNO,MC) - UTC(NIST) values

are averaged measurements from NAVSTAR satellites 3,4,6, and 8 (see references on page 6).

OCTOBER

1989 MJD

0000 HOURS COORDINATED UNIVERSAL TIME

UT1 - UTC (NIST)

(t 5 ms)

UTC - UTC(NIST)

( ± 0.2 us

)

UTC ( USNO, MC) -

(i 0.04

UTC(NIST)

us)

5 47804 -496 ms -0.2 us 0.73 us

12 47811 -507 ms -0.2 us 0.71 us

19 47818 -522 ms -0.2 us 0.71 us

26 47825 -537 ms -0.2 us 0.70 us

-

1 -
INTERNATIONAL njflNG CENTER COMPARISONS VIA GPS COMCN-VIEN

The table below is a weighted average of the indicated GPS satellites used as transfer standard * tiHje difference of Timing Center (i) - UTC(NIST) by the simultaneous common-view approach (see rJp

meaSUre the

6). The day-to-day variations of this technique are a few nanoseconds and the accuracy is about lO^s

065

TM

15386 time of the measurement is interpolated to 0000 UTC for the particular MJD ending in 9 These data are noted

re<1 f ° r thS BIPM f° r thS COmputation on TAI and of UTC- All differential delays are 0 unless otherwise

UTC(i) - UTC(NIST) (ns) MJD

UTC(APL) - UTC (NIST) 3,6,9,11,12,13 50 59 47 32//

UTC (CRL) - UTC(NIST) 6, 12 14 725+ 726 728 746//

UTC(CSIRO) - UTC(NIST) ++ 22840+ 23060 23192 23343//

UTC(IEN) - UTC(NIST) 11,12,13,14 -444+ -368 -275 -196////

UTC(NPL) - UTC (NIST) 3, 11,12,13,14 1111+ 1378 1529 1593

UTC(NRC) - UTC ( NIST )+++ 3,6,9 ,11,12,13,14 14994 15178 15340 15513

UTC(OP) - UTC(NIST) 3, 11,12,13,14 323+ 185 72 -18

UTC(PTB) - UTC(NIST) 11 -4149+ -4073 -4002 -3945

UTC (TAO) - UTC(NIST) 6, 14 4014+ 4092 4199 4319

UTC (TUG) - UTC(NIST) 3, 11,12,13,14 -2656+ -2826 -2989 -3132

UTC(USNO,MC) - UTC (NIST) 3,6,9, 11,12,13,14 736+ 723 707 699

UTC(VSL) - UTC (NIST) 3, 11,12,13,14 -2096+ -2106 -2104 -2094

PLEASE NOTE: ^^^^^^cing receiver problems. Therefore, this station is not included in this month' s

lu utrJurtVl

updated from those Printed in last month's Bulletin. UTC(CSIRO) - UTC (NIST) is computed from the average of CRL, TAO & WWVH -H-+ UTC(NRC) - UTC(NIST) has a differential delay of 41.2 ns- all other comnari^nne

(q ) . * 5 ’ ocner comparisons are computed using zero UTC ^^ month).

L) experienced^ time step of approximately -1792 ns on MJD 47790 (correction of MJD from last The value given is computed from unfiltered data.

These values for MJD 47829 were extrapolated forward from 47828.

These values for MJD 47829 were extrapolated forward from 47827.

0

//

////

3. UT1 CORRECTIONS AND LEAP SECOND ADJUSTMENTS

Sc(NT^W

Cl0Ck P?

lseV

Sed by bhe WW* W*TM* WWVB, and GOES time code transmissions are referenced to the

slcind T^

me '• °CCaai0na1

second.

^* 1 seco"d added to the UTC time scale. This second is called I leap

changes

Its purpose is to keep the UTC time scale within i 0.9 s of the UT1 astronomical time scale which slightly due to variations in the rotation of the earth.

TP°J

itive leap seconds ‘ beginning at 23 h 59 min 60 s UTC and ending at 0 h 0 min 0 s UTC were inserted in the

When

bTC timescaie on 30 June 1972, 31 December 1972-1979, 30 June 1981-1983, 30 June 1985, and 31 December 1987 future leap seconds are scheduled, advance notice will be provided in this bulletin.

m -

S

rJT? fii

eaP nT^S th4t OT1 " 010 wil1 always be held within * 0.9 s. The current value of UTC is called the DUT1 correction. DUT1 corrections are broadcast by WWV, WWVH, WWVB, and GOES and are printed below. These corrections may be added to received UTC time signals in order to obtain UT1

.

DUT1 = UT1 - UTC

-0.4 s beginning 0000 UTC 08 June 1989

-0.5 s beginning 0000 UTC 21 September 1989

-0.6 s beginning 0000 UTC 16 November 1989

SPECIAL ANNOUNCEMENT: A positive leap second will be introduced at the end of December 1989, of dates of the UTC second markers will be:

1989 December 31, 23h 59m 59s

1989 December 31, 23h 59m 60s

1990 January 1, Oh 0m Os

The sequence

- 2 -
4. PHASE DEVIATIONS FOR WWVB AND LORAN-C

WWVB - The values shown for WWVB are the time difference between the time markers of the UTC(NIST)

time scale and the first positive-going zero voltage crossover measured at the transmitting

antenna. The uncertainty of the individual measurements is ± 0.5 us. The values listed are

for 1500 UTC.

LORAN-C - The values shown for Loran-C represent the daily accumulated phase shift (in microseconds).

The phase shift is measured by comparing the output of a Loran receiver to the UTC(NIST) time

scale for a period of 24 hours. If data were not recorded on a particular day, the symbol

(-) is printed.

The stations monitored are Dana, Indiana (8970 M) and Fallon, Nevada (9940 M). The

monitoring is done from the NIST laboratories in Boulder, Colorado.

UTC(NIST) - WWVB( 60 kHz)

UTC(NIST) - LORAN PHASE (in us)

DATE MJD

ANTENNA PHASE

(us)

LORAN-C (DANA)

(8970 M)

LORAN-C (FALLON)

(9940 M)

10/01/89 47800 5.61 +0.15 +0.09

10/02/89 47801 5.57 (-) (-)

10/03/89 47802 5.65 (-) (-)

10/04/89 47803 5.62 (-) +0.07

10/05/89 47804 5.60 +0.11 +0.16

10/06/89 47805 5.68 -0.16 -0.20

10/07/89 47806 5.65 -0.09 -0.03

10/08/89 47807 5.61 +0.04 -0.07

10/09/89 47808 5.57 (-) +0.14

10/10/89 47809 5.54 (-) -0.08

10/11/89 47810 5.68 +0.02 +0.03

10/12/89 47811 5.65 +0.00 -0.02

10/13/89 47812 5.70 -0.29 -0.44

10/14/89 47813 5.67 -0.02 +0.01

10/15/89 47814 5.64 +0.13 -0.01

10/16/89 47815 5.61 -0.11 -0.05

10/17/89 47816 5.70 -0.20 +0.09

10/18/89 47817 5.72 (-) +0.28

10/19/89 47818 5.67 -0.18 +0.02

10/20/89 47819 5.67 -0.06 -0.19

10/21/89 47820 5.65 +0.14 -0.20

10/22/89 4782i 5.63 +0.04 +0.25

10/23/89 47822 5.61 -0.27 -0.26

10/24/89 47823 5.69 +0.22 -0.25

10/25/89 47824 5.67 -0.11 +0.26

10/26/89 47825 5.66 -0.15 -0.40

10/27/89 47826 5.65 -0.05 -0.11

10/28/89 47827 5.65 (-) +0.33

10/29/89 47828 5.65 (-) -0.05

10/30/89 47829 5.65 -0.37 -0.35

10/31/89 47830 5.65 +0.16 +0.19

- 3 -
5. GOBS TIME CODE INFORMATION

A. TIME CODE PERFORMANCE (1-31 October 1989)

GOES/East: Performance within normal limits during this period.

GOES/West

Performance within normal limits during this period.

B. SPECIAL REMINDER: Current satellite locations are 65° West longitude for GOES/East and 135° West

longitude for GOES/West.

C. GOES STATUS REPORTS

A brief message from the NIST giving current GOES time code status information is available from the U.S.

Naval Observatory's Automated Data Service computer system in Washington, DC. The message may be accessed

24 hours per day without charge by using a variety of terminals operating at 300, 1200, or 2400 Baud and even parity. Two different sets of telephone access numbers are available: (1) for 300 or 1200 Baud and

the Bell 103 standard use (202) 653-1079 (commercial), 653-1079 (FTS), or 294-1079 (Autovon); (2) for 1200 or 2400 Baud with either the CCITT V.22 standard or the Bell standard use (202) 653-1783 (commercial),

653-1783 (FTS), or 294-1783 (Autovon). To receive the GOES status message, use the following procedure:

1. Access the USNO computer database by dialing one of the appropriate telephone numbers above;

2. In response to the prompt for identification, type your name and the name of your organization,

followed by a carriage return;

3. Type "@NBSGO" followed by a carriage return to receive the status message at your terminal;

4. Disconnect by typing Control-D.

6. BROADCAST OUTAGES OVER 5 MINUTES AND WWVB PHASE PERTURBATIONS

OUTAGES PHASE PERTURBATIONS WWVB 60 kHz

OCTOBER BEGAN ENDED OCTOBER BEGAN ENDED

STATION 1989 MJD (UTC) (UTC) FREQUENCY 1989 MJD (UTC) (UTC)

WWVB NONE • NONE

WWV NONE NONE

WWVH NONE NONE

- 4 -
8. SPECIAL AMOUNCBfniTS

AUTOMATED COMPUTER TIME SERVICE (ACTS)

On March 9, 1988, NIST initiated operation of a telephone time service designed to provide computers with

telephone access to NIST time at accuracies approaching 1 ms. Features of the service include automated

compensation for telephone- line delay, advanced alert for changes to and from daylight savings time and

advanced notice of insertion of leap seconds. The ASCII-character time code should operate with standard

modems and most computer systems. While the system can be used to set computer time-of-day clocks, simple

hardware can also be developed to set other clock systems.

The test phase for this service is now complete and NIST is committed to long-term operation of the

service. Additional lines will be added as use expands. NIST requests that calling times be spread out so that the system is not heavily taxed in some narrow time frame (e.g., midnight). The service telephone number

is (303) 494-4774. The number may be changed at a later date. A help message can be obtained by returning a ? during the first 6 s of transmission.

With appropriate user software, the NIST-ACTS service provides three modes for checking and/or setting

computer time-of-day clocks.

1. In the simplest form of the (1200 Baud) service, the user receives the time code and an on-time

marker/character which has been advanced a fixed period to nominally account for modem and telephone- line

delays. Accuracy in this mode should be no worse than 0.1 s unless the connection is routed through a satellite.

2. At 1200 Baud, if the user's system echoes all characters to NIST, the round-trip line delay will be

measured and the on-time marker advanced to compensate for that delay. The accuracy in this mode should be

better than 10 ms. Our experience to date indicates that the asymmetry in conventional, 1200-Baud modems

limits the accuracy at this level. Repeatability is about 1 ms.

3. At 300 Baud the user can obtain the same type of service as described in item 2 above, but there is

generally less problem with modem asymmetry at this rate and our experience indicates that the accuracy is

about 1 ms.

The accuracy statements here are based upon the assumption that the telephone connection is reciprocal,

that is, that both directions of communication follow the same path with the same delay. Discussions with

telephone carriers indicate that this is the general mode of operation and our tests to date indicate that the

lines are both stable and reciprocal.

In order to assist users of the service, NIST has developed documentation of the features of the service,

some example software which can be used in conjunction with certain popular personal computers and simple

circuitry which can be used to extract an on-time pulse. This material is available on a 5i-in, 360-kbyte DOS

diskette with instructions for $35.00 from the NIST Office of Standard Reference Materials, B3 11 -Chemistry

Bldg, NIST, Gaithersburg, MD, 20899, (301) 975-6776. Specify the Automated Computer Time Service, RM8101.

Further technical questions and comments should be directed to NIST-ACTS, NIST Time and Frequency Division, 325

Broadway, Boulder, CO 80303.

44TH ANNUAL FREQUENCY CONTROL SYMPOSIUM

The 44th Annual Frequency Control Symposium will be held May 23 - 25, 1990 in Baltimore, MD. This

symposium is the leading technical conference addressing all aspects of frequency control and precision

timekeeping. Authors are invited to submit papers dealing with recent progress in research, development and

applications in areas represented by the following topics:

• Fundamental properties of piezoelectric crystals

• Theory and design of piezoelectric resonators

• Resonator processing techniques

• Filters

• Surface acoustic wave devices (SAW)

• Quartz crystal oscillators

• Microwave and millimeter wave oscillators

• Signal processing and frequency control circuitry

• Atomic and molecular frequency standards

• Frequency and time coordination and distribution

• Sensors and transducers

• Applications of frequency control

• Measurement and specifications

Contact: Dr. R. L. Filler, US Army Electronics Technology and Devices Laboratory, ATTN: SLCET-EQ, Fort

Monmouth, NJ 07703-5000; (201) 544-2467.

- 7 -
• ««» «*<' w *. oC»« e* <o«m*. li. jIliCaTIOn 0 *

lltllOCJUPMIC OATA

j SHEET flee ie>tfvction>) 1 NISTIR 89-3910* 11

4. t* «*•*• 889-0064

i. 5 in

November 1989

4, TITLE ANO SUtTlTLt

Tiat 4 Frequency Bulletin

i. authors)

I. PERFORMING ORGANIZATION (If ;OJAt Or OtN er (M«D N|S, let ia tt'wCtcOA ») NATIOMAL 9U9CAU OF STANDARDS

oeparthcnt of commerce

VASMIMOTOO. O.C. NIS4

1. Contract/Grant No.

I. Tr»« ef Report 4 F*ri*4 Cevered

•. SPONSORING ORGANIZATION NAME ANO COMPLETE AOORESS fStreeC"C«ir. itete.'TlPj

19. SUPPLEMENTARY NOTES

n Oocumant NicnMi a cemptier program; SF.I 9S. PiPS Software Summ«-y, It attadsed. I&. AOSTRACT (A ZOO* rd yt foil feetad* Summery of melt tlflflcynt Ia format Jen. If deceaiaei /»< f«dei « effaiffcaet

t/Af/afrepAf o/ literature tyMf, meat/ee It life/

Tht Tine 4 Frequency Bulletin provide* Information on performance of time

scales and s variety of broadcasts (and related Information) to users of tbs

NIST services.

12. KEY *OR0S (S»* to tw#/»e lAtrltt; e/phebeticef order; cep/tellse OA If proper domes; •«# separate k«r word* by iem»coi©«li

clocks; dissemination; frequency; CPS; oeclllators; time

IS. availability

I 1 Unlimited

mFor Official Distribution. Oo Not Rolooto to NTIS

f ~~1 Order From Superintendent of Oocgmante, U.S. Government Printing Office. Washington , O.C

20402.

[ 1 Order From National Technical Information Service (NTIS). Springfield, VA. 22141

- 8 -

14. NO. OF

PRINTED PAGES

IS. Price

USCObM'OC «04J *•#
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'

AN EQUAL OPPORTUNITY EMPLOYER

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National Institute of Standards and Technology

Time & Frequency Division

Boulder, Colorado 80303

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