Research On GNSS Real-time Clock Offset Fast Estimation And Integrity Monitoring Algorithm

With the gradual expansion of the application of real-time navigation and positioning technology,users' demand for high-precision and real-time positioning is increasing.The real-time wide-area differential service system is also quickly established.In wide-area differential products,the real-time orbits can be predicted by post-mortem precision products.The accuracy of the predicted orbits meets user needs and is used for real-time positioning.However,because the navigation satellite atomic clock is susceptible to internal noise and the external environment,the forecast accuracy is difficult to meet user needs,so the clock difference must be estimated in real time.At the same time,multi-system GNSS data processing and application has become a development trend in the field of GNSS;on the one hand,with the increasing number of on-orbit navigation satellites,the estimation efficiency has become a bottleneck for real-time estimation of satellite clock difference;When the clock difference is estimated,various system errors such as inter-system deviation and inter-frequency deviation must be fully considered to avoid being absorbed into the clock difference parameters and affecting the accuracy of the clock difference estimation.In addition,in order to provide users with reliable data,complete monitoring of satellite clock differences is required.Based on the investigation and analysis of the related research status and research hotspots at home and abroad and the absorption of previous research results,this paper has made some attempts and explorations on the rapid estimation of GNSS real clock difference and the complete monitoring algorithm.The main contents of this article are as follows:(1)The system introduces the basic theoretical knowledge of real-time satellite clock error estimation.By analyzing the clock error estimation observation model,the characteristics and correction methods of various error sources,and parameter estimation methods,a four-system satellite clock error real-time estimation is designed that takes into account the inter-system deviations Process flow.And introduces the complete monitoring method of satellite clock difference.(2)This paper mainly introduces the block QR decomposition method,and gives a multi-system GNSS satellite clock estimation method based on block QR decomposition.The results show that using 37 stations to estimate the satellite clock difference of four systems in real time,the average time of a single epoch of traditional methods is 5.004 seconds;and the estimation method based on block QR decomposition can increase the data processing efficiency to 2.9998 per epoch second.(3)By studying the satellite clock error completeness monitoring algorithm,a clock error data processing strategy based on epoch single difference method and fuzzy cluster analysis method is proposed.And analysis examples of simulated data and measured data are carried out to verify and analyze the effectiveness and related characteristics of the proposed processing strategy.