Abstract:
The Japanese QZSS satellite will provide real-time PPP services by broadcasting the L-band augmentation signals with real time high rate GNSS precise orbit and clock corrections. This paper based on the 1Hz high rate GPS clock provided by JAXA MADOCA data center, we firstly evaluates the short-term stability of satellite clock corrections with Allan variance. To simulate the real time products latency, the first-order, second-order polynomials and grey model were used as the clock predictions model, and the fitting windows with 5, 10 and 30 s were used to predict the following 10 s clocks corrections. Over 21 continuous days data range from January 1 to 21 on 2020 were used on the clock stability analysis, the results show that the GPS clocks can reach 10-12with 1, 5 and 10 s intervals. On the prediction model comparison, a whole days analysis results show that, if less than 10 s fitting windows were used, the first-order linear model shows highest stability with accuracy less than 0.1 ns, and if the fitting windows were set to 30 s, the second-order polynomial model has the highest accuracy as the clock drift effects were taken into account. It can be concluded that the satellite clocks from MADOCA-LEX product could be precisely predicted to satisfy the real-time precise point positioning applications.
