NBS time to the Western Hemisphere by satellite

Abstract

As a complement to the present time and frequency services of WWV, WWVH, and WWVB, the National Bureau of Standards (NBS) is now providing a satellite‐disseminated time code using the Geostationary Operational Environmental Satellites (Goes) of the National Oceanic and Atmospheric Administration (NOAA). The time code is referenced to the NBS time scale, giving coordinated universal time (UTC). In addition to the usual information of day of year, hours, minutes, seconds, and the UTl correction the time code contains the satellite's current position for use in path delay calculations. The time signals are relayed to the entire Western Hemisphere from two geostationary satellites on a full‐time basis except during brief periods of solar eclipses occurring during the vernal and autumnal equinoxes. The time code, originally intended for use by environmental monitoring platforms, is easily accessible by anyone using relatively simple, commercially available equipment. Physically small antennas (30 cm × 30 cm × 1cm) are typical. The generation, satellite relay, and recovery of these signals is discussed. Results obtained with commercial receiving equipment are included.

The GOES time code service, 1974-2004: A retrospective

“…The CDA continuously relays interrogation messages to both GOES-East and GOES-West via two 18.3 m diameter parabolic antennas at an S-band frequency of approximately 2034 MHz. The interrogation messages are sent back to Earth at downlink frequencies of 468.825 MHz from GOES-West and 468.8375 MHz from GOES-East at a data rate of 100 bits per second, using just 400 Hz of bandwidth [ 29 , 30 ].…”

“…Corrected mode required the receiver to have a microprocessor so it could read the ephemeris data code, and compute the free space delay from the satellite to the receiver’s antenna (the receiver’s coordinates were entered by the user and stored in memory). This improved the timing uncertainty to ±100 µs [ 30 ], and allowed GOES to become the first time code service of any type that allowed receivers (Sec. 8) to automatically correct for path delay.…”

“…GOES time at the CDA was synchronized by NIST personnel using a number of techniques throughout the years, including the use of television signals from nearby Norfolk, Virginia, LORAN-C transmissions from Cape Fear, North Carolina [ 29 , 30 ], portable clock carries from Boulder to Wallops Island [ 39 ], and eventually through the use of GPS signals [ 32 ]. The performance of the station clock was continuously monitored from Boulder using a remote controlled data logger [ 40 ], which was replaced by more modern equipment in 1999.…”

Calibration and related measurement services of the National Bureau of Standards

“…An effort will be made to discuss the measurement requirement with the customer so as to give proper service at minimum cost and delay. [6] Preparations for gage block comparison measurements, C. D. Tucker, NBSIR 74-523, 14 pages (July 1974). Order from NTIS as COM 75-1 1 126.…”