Quality Evaluation And Fast Determination Of GNSS Precise Satellite Clock Bias

Satellite clock bias as to keep the synchronization of space and ground time of navigation system,plays an important role in satellite navigation and positioning applications.This paper mainly analyzes the atomic clock performance and its products and studies the fast determination and prediction method of precise satellite clock bias.The main work and results are summarized as follows:1.The data integrity and accuracy of broadcast ephemeris satellite clocks of GNSS systems are evaluated using the post-precision satellite clock bias issued by the GFZ Analysis Center.The results show that the Galileo system has the highest accuracy,followed by GPS and BeiDou system,whereas GLONASS system is the lowest,and the satellite clock bias quality of the satellite which are equipped with H atomic clock is significantly higher than that are equipped with Cs and Rb atomic clocks.Besides,the product qualities of different precise satellite clock bias and their influences on precise point positioning are evaluated.2.The comparison of several mount points that are transmitting real-time satellite clock correction shows that the data receiving rate of IGS03 is the highest,and its average receiving rates of GPS and GLONASS real-time satellite clock error correction are as high as 98.63% and 98.58% respectively,while the data receiving rate of CLK53 is the lowest,only 93.05%.The average data receiving rate of GLONASS is 97.57%,followed by GPS and Galileo,95.74% and 94.37%,respectively,and BeiDou is the lowest,only 87.67%.The real-time satellite clock correction accuracies of different analysis centers are nearly the same,which can satisfy the requirement of real-time precise point positioning.3.Several GNSS analysis centers,such as CODE,GFZ and WHU,provide BeiDou clock products and these products are collected and released by the IGS Multi-GNSS Experiment(MGEX).This paper analyzes the performance of different sampling interval clock data of different GNSS analysis centers and makes comparison on the continuity,consistency,fitting accuracy and prediction characteristic of these clock data.At the same time,the short-term frequency stability of BeiDou satellite clock is evaluated with BeiDou satellite clock products,and some useful conclusions are drawn.4.In order to improve the efficiency of undifferenced estimation of satellite clock bias on the premise of acquiring high accuracy result,this paper optimizes the matrix design and data processing in the process of satellite clock bias estimation,and improves its calculating speed.On the basis of observation data of global distribution uniformity of IGS reference station and the use of self-compiled software,the results show that the proposed method in this paper can achieve rapid estimation of precise satellite clock bias.Compared with the traditional algorithm,the calculation time can be saved by more than 90% using the new algorithm.5.In order to improve the performance of satellite clock bias prediction,a new prediction method is proposed considering periodic errors and stochastic characteristics.The precise data of satellite clock bias within 15 minutes from IGS are used to conduct experiment on different models.The result shows that the model with two dominating periodic errors is better than the model with other dominating periodic errors,the proposed model performs better than commonly used models in short-term prediction and it shows better performance for satellite with rubidium atomic clock than cesium atomic clock in mid-long term prediction.6.Based on GNSS data processing software GNSSer,GNSS satellite clock differential decoding software prototype is developed,and its design method and functional components are introduced in detail.