GNSS Systems strongly rely on measuring the time of arrival of radio signals propagation. Thus, each GNSS System has its own time reference from which all elements of the Space, Control and User segments are time synchronized, as well most of the GNSS-based applications. The most relevant GNSS time references are briefly described below.

GNSS  Timing Center 

RKTPL has expertise to setup highly precise timing center for GNSS (Global Navigation Satellite Systems ). We help Space programs in following segments:

  • Highly Precise Timing Center for GNSS.
  • Generate maintain and disseminate GNSS network time using an ensemble of highly stable atomic clocks.
  • Estimate
    • onboard satellite clock bias and drift rate
    • Ionospheric delay
  • Enable 24X7 automated operation of the GNSS Ground Segment
  • Setup Timing Center as the reference timescale for the GNSS system for the generation, dissemination and maintenance of a precise and stable system time of GNSS.
  • Ensemble of Active Hydrogen Masers, Passive Hydrogen Masers and Cesium atomic clocks.
  • Timescale output will be steered to a desired reference.

There are many ways to improve the GNSS accuracy. The stability of the satellites’ onboard clocks can be improved from 5 x 10–13 to 1 x 10–13 over 24 hours with precision thermal stabilization.Let’s discuss your project to offer you highly precise timing facility for ground and space segments.



GPS Time (GPST) is a continuous time scale (no leap seconds) defined by the GPS Control segment on the basis of a set of atomic clocks at the Monitor Stations and onboard the satellites. It starts at 0h UTC (midnight) of January 5th to 6th 1980 (6.d0). At that epoch, the difference TAI−UTC was 19 seconds, thence GPS−UTC=n − 19s. GPS time is synchronised with the UTC(USNO) at 1 microsecond level (modulo one second), but actually is kept within 25 ns.


GLONASS Time (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 (i.e.,GLONASST=UTC(SU)+3hτ, where |τ|<1milisec.), but τ is typically better than 1 microsecond. Note: Unlike GPS, Galileo or BeiDou, GLONASS time scale implements leap seconds, like UTC.

Galileo System Time (GST)

Galileo System Time (GST) is a continuous time scale maintained by the Galileo Central Segment and synchronised with TAI with a nominal offset below 50 ns. The GST start epoch is 0h UTC on Sunday, 22 August 1999 (midnight between 21 and 22 August).

BeiDou Time (BDT)

BeiDou Time (BDT) is a continuous time scale starting at 0h UTC on January 1st, 2006 and is synchronised with UTC within 100 ns< (modulo one second).

For Further Information

Please Contact Us for more information.