The method of refining real-time satellite clock offset reference

For timing based on PPP method, the high-accuracy time reference of satellite clock products is very important. Aiming at the problem that the time reference of real-time satellite clock products is not stable enough, this paper uses a set of IGS tracking stations with external input of atomic clock to establish a reference refinement method that takes into account the variation characteristics of atomic clocks. Firstly, we analyze the stability of the external atomic clock of the IGS tracking station based on Allan variance, and select highly stable atomic clocks to correct the time reference. On this basis, the Allan variance is used to calculate the noise parameters of each atomic clock and the corresponding weight ratio relationship. Finally, this paper establishes a stochastic model of time reference corrections and calculates the time reference after refinement. By comparing with the time reference implied by the IGS precision clock products, the STD of the corrected time reference is better than 0.1 ns in a single day, up to 93％ compared to before the correction. At the same time, the long-term stability at 10 000 s can reach the level of 10^-15, achieving an order of magnitude improvement.