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GLONASST is generated by the GLONASS Central Synchroniser and the differ- ence between the UTC(SU) and GLONASST should not exceed 1 millisecond plus three hours<ref group="footnote">The difference between Moscow Time and Greenwich Mean Time (GMT).</ref> (i.e.,<math>t_{GLONASS}=t_{UTC(SU)}+3^h-\tau</math>, where <math>|\tau|< 1
GLONASST is generated by the GLONASS Central Synchroniser and the difference between the UTC(SU) and GLONASST should not exceed 1 millisecond plus three hours<ref group="footnote">The difference between Moscow Time and Greenwich Mean Time (GMT).</ref> (i.e.,<math>t_{GLONASS}=t_{UTC(SU)}+3^h-\tau</math>, where <math>|\tau|< 1
milisec.</math>).
milisec.</math>).


Revision as of 09:04, 17 January 2012


FundamentalsFundamentals
Title Time References in GNSS
Author(s) J. Sanz Subirana, J.M. Juan Zornoza and M. Hernández-Pajares, Technical University of Catalonia, Spain.
Level Basic
Year of Publication 2011

Regarding the GNSS, the GPS Time (GPST), GLONASS Time (GLONASST), Galileo System Time (GST) and BeiDou Time (BDT) are the reference times used in GPS, GLONASS, Galileo and Compass applications, respectively.


GPST is defined by the GPS Control segment on the basis of a set of atomic clocks aboard the satellites and in the Monitor Stations. It is synchronised with the UTC(USNO) at nanosecond level. The origin epoch of GPS time is 0h UTC (midnight) of January 5th to 6th of 1980 (6d· 0). At that epoch, the difference TAI−UTC was 19 seconds, thence GPS−UTC=n − 19s.


GLONASST is generated by the GLONASS Central Synchroniser and the difference between the UTC(SU) and GLONASST should not exceed 1 millisecond plus three hours[footnote 1] (i.e.,[math]\displaystyle{ t_{GLONASS}=t_{UTC(SU)}+3^h-\tau }[/math], where [math]\displaystyle{ |\tau|\lt 1 milisec. }[/math]).


GST will be maintained by the Galileo Central Segment and synchronised with TAI with a nominal offset below 50 ns. The starting time of Galileo system is not already defined.


Notes

  1. ^ The difference between Moscow Time and Greenwich Mean Time (GMT).

References

  • Hofmann-Wellenhof, B., Legat, K. and Wieser, M., 2003. Navigation. Principles of positioning and guidance. Springer-Verlag, Wien, Austria.
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