Gps And Glonass System Time - ashtech GG Surveyor Reference Manual

Satellites per plane
Orbital inclination
Orbital radius
Orbital period
Duration
Capacity
Time reference
Geodetic datum

GPS and GLONASS System Time

GPS system time is equal to UTC time + the number of leap seconds added since
1980 (currently 12 seconds). GLONASS system time is equal to UTC time + 3 hours.
There is an additional GLONASS time shift relative to GPS time of approximately
-28.6 microseconds. Therefore, when UTC time equals 00:00:00.000000, GPS system
time equals 00:00:12.000000, and GLONASS system time equals 00:02:59.9999714.
In other words, GLONASS system time leads GPS system time by 3 hours minus the
number of leap seconds plus the sub-second time shift value, which is currently equal
to 2:59:47.9999714 (as of 30 June 1997).
GPS+GLONASS Standards
Two standards are used widely and successfully for GPS applications. These are
Although both these standards were initially for marine use, they have been adopted
worldwide for all applications of GPS.
RTCM SC-104
The RTCM Special Committee 104 (SC-104) has defined differential correction
messages that are used worldwide for GPS. The messages that carry the GPS
A-6
Table A.1: Comparison of GPS and GLONASS (continued)
Parameter
UTC (US Naval Observatory)
RTCM (Radio Technical Commission for Maritime Services) standard for
differential corrections
NMEA (National Marine Electronics Association) standard for reporting
position, velocity and satellite data.
GPS
4, unevenly spaced
55°
26560 km
11 hours 58 minutes
NAVIGATION MESSAGE
12.5 minutes
37500 bits
WGS-84
GG Surveyor GPS+GLONASS Reference Manual
GLONASS
8, evenly spaced
64.8°
25510 km
11 hours 15 minutes
2.5 minutes
7500 bits
UTC (SU, Russia)
PZ-90