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Home》Time and Frequency Transfer/
GPS Observations
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GPS and Glonass Observations
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Due to clocks has become more precisely and accurately, the timing community is continuously seeking more precise and accurate systems to help them with synchronization. Global positioning system (GPS) is not only a navigation system, but also a reliable time-transfer system.
A GPS receiver can be programmed to display the difference between the local clock and the GPS time. GPS can easily provide the capability to allow synchronization of clocks to better than 100 ns in time.
In the technique of GPS common view, two GPS receivers (known as GPS time transfer units) simultaneously observe the same GPS satellite. Two clocks located at different sites can compare with each other by means of the GPS time derived by the two GPS receivers. Since the GPS time is common, the difference between the outputs from the two GPS receivers, programmed as mentioned above, is simply the difference between the two clocks. The technique known as GPS common view can be used to synchronize clocks over a large geographical area with uncertainty as good as 3-5 ns.
For the routine international collaboration, TL operates two AOA TTR6 GPS receiver and obeys the recommended GPS common-view tracking schedules of BIPM. Data in the CCDS format are sent to BIPM per monthly. A GPS/GLONASS multi-channel receiver R100-30T from 3S navigation is operating for test now. An Ashtech Z12T GPS receiver is set for the research of IGS/BIPM pilot project. Two Ashtech Z-survery GPS receivers are operating to study the GPS carrier phase time and frequency transfer.
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