Precision Evaluation And Consistency Analysis Of IGMAS Products

iGMAS is the world’s continuous monitoring and evaluation system initiated by China in the international arena. iGMAS aims to establish a global distribution network of GNSS signal tracking to provide services to global customers, through precision GNSS receivers and high-gain omnidirectional antenna, it can monitor service performance and signal quality of GNSS. GNSS global users via the internet not only to obtain monitoring and assessment service information for each GNSS system, but also can get some high-precision data products. Similar to IGS, iGMAS products include GNSS four systems’ precise orbit/clock,iGMAS station coordinates and velocity, ERP, geocentric change and troposphere/ionosphere products. Precision and consistency of these products is basic protection to ensure users carry out high-precision positioning and navigation. This paper focuses on precision evaluation and consistency analysis of iGMAS orbit and clock products. consistency were analyzed based on PPP technical. In addition, the difference of reference framework in iGMAS orbit, station coordinates and ERP products resulting from different strategies, will also bring navigation and positioning error, the paper systematically studied consistency of reference framework between these three products, and it’s the basic insurance for high-precision navigation and positioning. Main achievements and contributions are as follows:1. Interpolation error of satellite clock difference were studied by comparison of the different order Lagrange interpolation accuracy, and conclusions that the accuracy loss caused by interpolation is less than mm when orbit and clock products are transferred from BDST to GPST. So in practical application it can be without considering the error.2. Using a differential method, DBD method and the second-order difference method respectively, the accuracy of orbit and clock product from iGMAS different analysis centers were assessed. The result shows that:there are some gaps of products precision between iGMAS analysis centers and CODE, but with the completion of the global BDS system, this gap will be gradually reduced.3. The method of using PPP technology to analyze the consistency of satellites’ orbit and clock products is put forward. Selected two groups orbit and clock products with equivalent accuracy and MGEX stations with good quality observation to calculate single epoch PPP, the PPP precision can indirectly reflect the orbit and clock products’ consistency.4. The method with using the seven parameters of Helmet transform to analyze the consistency of the reference frames defined by orbit, station coordinate and ERP products is put forward. And on the basis, a method for quantitative analysis of the correlation coefficient between the conversion parameters is proposed. With iGMAS measured data, the consistency of the three products’ reference frame is anayezed and compared which is generated by different analysis centers.