The test and evaluation of GPS on-board clock

In satellite navigation system, the main time-frequency equipment of space segment is on-board clock, and its performance directly related to the pseudo code ranging and doppler effect observation precision, then affects the satellite navigation system orientation, velocity measurement and time service, so the test and evaluation of the on-board clock is very important. The methods and indicators used to evaluate the on-board clock in this paper. The performance of GPS on-board clock is evaluated based on the GPS on-board clock time difference data released by the IGS. Using Hadamard variance to evaluate the stability, the results show that the stability a day of most GPS on-board atomic clocks can reach 2×1014, in the time interval of 5 days, the stability reaches the highest level.