Time synchronization in North America explained

Time synchronization in North America can be achieved with many different methods, some of which require only a telephone, while others require expensive, sensitive, and rare electronic equipment. In the United States, the United States Naval Observatory provides the standard of time, called UTC(USNO), for the United States military and the Global Positioning System,[1] while the National Institute of Standards and Technology provides the standard of time for civil purposes in the United States, called UTC(NIST).

ITU-R Standard Frequency and Time Signals

A standard frequency and time signal service is a station that operates on or immediately adjacent to 2.5 MHz, 5 MHz, 10 MHz, 15 MHz, 20 MHz, and 25 MHz, as specified by Article 5 of the ITU Radio Regulations (edition 2012).[2] The US service is provided by radio stations WWV (Colorado) and WWVH (Hawaii).

The methods below provide either Coordinated Universal Time (UTC), which is defined by Recommendation ITU-R TF.460,[3] or the official U.S. implementation of UTC, officially labeled UTC (NIST).

Internet time sources

Several different time synchronization protocols exist on the Internet, including:

!Protocol!RFCs!Accuracy!Ports!Time servers
Daytime ProtocolRFC 868Nearest secondTCP port 13
Time Protocol (a.k.a. NETDATE)RFC 868Nearest secondTCP/UPD part 37
NTP RFC 1305, RFC 5905
SNTPRFC 1769, RFC 2030
ICMP TIMESTAMPRFC 0792, page 16
IP TIMESTAMP optionRFC 0791, 3.1, page 16

GPS time synchronization

GPS receiver requirements

Utility frequency

In 2009 the Federal Energy Regulatory Commission made time error correction (TEC) of the power grid frequency mandatory.[9] While TEC does not provide full synchronization (date and time) and synchronization is lost in case of a power outage it provides an inexpensive way to maintain high long term accuracy of synchronous clocks found in most household appliances. Once the initial time is set the power grid will typically maintain the accuracy within 10 seconds relative to UTC by adjusting frequency.[10]

All time sources

Several different organizations provide publicly accessible recorded voice time sources, including the NIST Telephone Time of Day Service, see speaking clock. Other sources include GPS, terrestrial radio time signals, and internet services, as listed below.

North American Time Synchronization Sources!Time Signal!Time Provided!Accuracy!Source!Signal Format!Hardware Requirements!Linux/Unix Software!Windows Software
GPSUTC(USNO)NMEA 0183 sentences, 1PPS signal.Minimum: GPS receiver that works with one's chosen software; this requires some combination of GPGGA, GPRMC, GPZDA, GPGSA, and GPGSV, sentences.

Ideal: GPS receiver (OCXO/DOCXO disciplined clock preferred) with NMEA 0183 output on RS-232 or USB, with GPZDA sentence sent at least once a second, and 1PPS signal on DCD, which includes at least these devices:

  • ZTI Z050 GPS dongle[11]
  • Garmin GPS 18x OEM
  • Gpsd plus ntpd with the GPSD NG client driver[12]
WWVBUTC(NIST)60 kHz AMIRIG "H" PWM time code with PM BPSK signal overlaid.[18] Radio-controlled clock
  • NIST list of receivers[19]
  • AC-100-WWVB Time Receiver
  • AC-500-MSF Time Receiver
  • ClockWatch Radio Sync[20]
  • F6CTE's CLOCK
WWV2.5, 5, 10, 15, and 20 MHz AMVoice with modified IRIG-Hformat time code on 100 Hz sub-carrier (CCIR code)
  • HF radio and antenna (plus software if automatic updating of computer time is desired)
  • TrueTime TL-3 WWV Receiver
  • ntpd with Radio WWV Audio Demodulator/Decoder (driver can tune ICOM HF radios via C-IV)
  • COAA's Radio Clock[21]
  • F6CTE's CLOCK
WWVH5, 10, and 15 MHz AMVoice with modified IRIG-Hformat time code on 100 Hz sub-carrier (CCIR code)
  • HF radio and antenna (plus software if automatic updating of computer time is desired)
  • TrueTime TL-3 WWV Receiver
CHU3.33 MHz, 7.85 MHz, 14.67 MHzBell 103 modem tones, decodable by most computer modems
  • ntpd with Radio CHU Audio Demodulator/Decoder driver (driver can tune ICOM HF radios via C-IV)
Daytime ProtocolUTC (variant depends on server's time source)
  • ClockWatch Pro for Windows[22]
Time Protocol
Network Time Protocolpool.ntp.orgComputer with NTP client that syncs at least once an hour.ntpd, sntp, ntpdate
  • Meinberg NTP[23]
  • NetTime[24]
  • ToyNTP
  • BktTimeSync by IZ2BKT
NTPSec
Precision Time Protocol
NIST Telephone Time of Day Service[26] UTC(NIST)
  • +
  • +
Voice announcement with sync pips.Telephone connection, earn/aManual sync only.
NIST Automated Computer Time Service (ACTS)[27]
  • +1-303-494-4774
  • +1-808-335-4721
Windows computer with dialup modem.
  • ntpd with NIST/USNO/PTB Modem Time Services driver
  • ClockWatch Pro for Windows
USNO Master Clock modem time[28] +1-202-762-1594Computer with Bell 212A or CCITT V.22 compatible modem
US Naval Observatory time serviceUTC(USNO)
  • +1-202-762-1401
  • +1-202-762-1069 (Washington, D.C.)
  • +1-719-567-6742 (Colorado Springs)
earn/a

See also

External links

Notes and References

  1. Web site: US Naval Observatory Precise Time Department. 2018-01-15. 2019-08-26. https://web.archive.org/web/20190826164130/https://tycho.usno.navy.mil/. live.
  2. ITU Radio Regulations, CHAPTER II – Frequencies, ARTICLE 5 Frequency allocations, Section IV – Table of Frequency Allocations
  3. Web site: TF.460 : Standard-frequency and time-signal emissions. www.itu.int. 2018-01-11. 2018-03-04. https://web.archive.org/web/20180304074112/http://www.itu.int/rec/R-REC-TF.460/en. live.
  4. Web site: NMEATime2 . www.visualgps.net . 2018-01-15 . 2018-01-16 . https://web.archive.org/web/20180116081105/http://www.visualgps.net/NMEATime2/MoreInfo.html . live .
  5. Web site: Compatible GPSes. gpsd.gitlab.io. 2021-10-27. 2021-10-23. https://web.archive.org/web/20211023231637/https://gpsd.gitlab.io/gpsd/hardware.html. live.
  6. Web site: Garmin GPS 18x OEM™ | Sensor. 2018-01-11. 2018-01-12. https://web.archive.org/web/20180112044112/https://buy.garmin.com/en-US/US/p/27594. live.
  7. Web site: GPS time synchronization tutorial. Lammert. Bies © 1997-2021. 2021-10-27. 2021-05-02. https://web.archive.org/web/20210502023643/https://www.lammertbies.nl/comm/info/gps-time. live.
  8. Web site: An NTP Stratum-1 clock usng a GPS 18 LVC and Windows 2000/XP/Windows-7. www.satsignal.eu. 2018-01-11. 2018-01-07. https://web.archive.org/web/20180107201221/http://www.satsignal.eu/ntp/NTP-on-Windows-serial-port.html. live.
  9. Web site: Western Electricity Coordinating Council Regional Reliability Standard Regarding Automatic Time Error Correction . May 21, 2009 . . June 23, 2016 . December 21, 2016 . https://web.archive.org/web/20161221015250/https://ferc.gov/whats-new/comm-meet/2009/052109/E-14.pdf . dead .
  10. Web site: Manual Time Error Correction. naesb.org. 4 April 2018.
  11. Web site: z050 USB GPS Dongle. ZTI Communications. 2018-01-11. 2018-01-12. https://web.archive.org/web/20180112042509/https://www.zti-communications.com/z050-gps-dongle/. live.
  12. Web site: GPSD NG client driver. 2018-01-17. 2018-01-28. https://web.archive.org/web/20180128100017/http://doc.ntp.org/4.2.8/drivers/driver46.html. live.
  13. Web site: NMEATime2. 2018-01-11. 2016-10-25. https://web.archive.org/web/20161025040641/http://www.visualgps.net/NMEATime2/. live.
  14. Web site: GPSTime. www.coaa.co.uk. 2018-01-11. 2016-12-28. https://web.archive.org/web/20161228025939/https://www.coaa.co.uk/gpstime.htm. live.
  15. Web site: CLOCK . f6cte.free.fr . 2018-01-11 . 2018-01-04 . https://web.archive.org/web/20180104222238/http://f6cte.free.fr/index_anglais.htm . live .
  16. Web site: DX Atlas: Amateur Radio software. www.dxatlas.com. 2018-01-15. 2018-01-16. https://web.archive.org/web/20180116225117/http://dxatlas.com/ToyNtp/. live.
  17. Web site: BktTimeSync - BktSoftware. IZ2BKT-Capelli. Mauro. www.maniaradio.it. 2021-10-27. 2021-03-23. https://web.archive.org/web/20210323195041/https://www.maniaradio.it/en/bkttimesync.html. live.
  18. Web site: WWVB Time Code Format. 2018-01-11. 2018-01-12. https://web.archive.org/web/20180112043137/https://www.nist.gov/pml/time-and-frequency-division/time-services/wwvb-time-code-format. live.
  19. Web site: Manufacturers of Time and Frequency Receivers. NIST . 5 January 2010. 11 January 2018. 12 January 2018. https://web.archive.org/web/20180112042533/https://www.nist.gov/pml/time-and-frequency-division/time-services/manufacturers-time-and-frequency-receivers. live.
  20. Web site: Radio Sync - WWVB Receiver and Software for Windows. www.beaglesoft.com. 2018-01-11. 2017-12-31. https://web.archive.org/web/20171231194903/http://beaglesoft.com/radsynhome.htm. live.
  21. Web site: Radio Clock. www.coaa.co.uk. 2018-01-11. 2017-08-11. https://web.archive.org/web/20170811191846/http://coaa.co.uk/radioclock.htm. live.
  22. Web site: Comparison of ClockCard Editions. www.beaglesoft.com. 2018-01-11. 2017-11-04. https://web.archive.org/web/20171104174813/http://www.beaglesoft.com/clwafeateditions.htm#ClockWatch+Pro+95. live.
  23. Web site: Meinberg NTP Software Downloads. www.meinbergglobal.com. 2018-01-11. 2017-12-23. https://web.archive.org/web/20171223235000/https://www.meinbergglobal.com/english/sw/ntp.htm. live.
  24. Web site: NetTime - Network Time Synchronization Tool. www.timesynctool.com. 2018-01-11. 2018-01-18. https://web.archive.org/web/20180118072911/http://www.timesynctool.com/. live.
  25. Web site: Domain Time II. www.greyware.com. 2018-01-11. 2018-01-12. https://web.archive.org/web/20180112100827/https://www.greyware.com/software/domaintime/index.asp. live.
  26. Web site: Telephone Time-of-Day Service. NIST . 24 September 2009. 11 January 2018. 27 November 2018. https://web.archive.org/web/20181127163229/https://www.nist.gov/pml/time-and-frequency-division/services/telephone-time-day-ttds. live.
  27. Web site: Automated Computer Time Service (ACTS). NIST . 23 September 2009. 11 January 2018. 12 January 2018. https://web.archive.org/web/20180112043142/https://www.nist.gov/pml/time-and-frequency-division/services/automated-computer-time-service-acts. live.
  28. Web site: USNO Master Clock modem time. 2018-01-15. 2017-12-27. https://web.archive.org/web/20171227233738/http://tycho.usno.navy.mil/modem_time.html. live.

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