The study of GPS Time Transfer based on extended Kalman filter

GPS Time Transfer is a perfect combination of the advantages of GPS atomic clock group and the receiver crystal oscillator. But is now mostly just used code pseudorange observation equation solving user clock offset in GPS timing receiver, while ignoring the impact of the receiver clock drift. In order to improve the GPS receiver Timing precision, the single satellite timing method is discussed, and the extended Kalman filter algorithm is used to estimate and predict the clock offset and clock drift. The receiver clock model is constructed by the clock offset and clock drift. The clock offset and clock drift have integral relationship, and often used as Kalman filter state variables. The white noise spectral amplitudes of clock offset noise and clock drift noise can be related to the classical Allan variance parameters Based on relationship between Allan Variances and Power spectral density Parameters. The pseudorange-rate equation is derived according to pseudorange observation equation. The error source is analyzed and quantified with respect to the pseudorange and the pseudorange-rate. The EKF method is tested and verified based on IGS data, and the timing precision of the GPS single satellite can be improved through this method.