18. The iGMAS Combined Products and the Analysis of Their Consistency

Several analysis centers (AC) and a product integration and service center have been built by the international GNSS continuous Monitoring and Assessment System (iGMAS). Product integration and service center (ISC) is a reprocessing center of high-precision products, which is also the window of products distribution center. Product integration and service center analyzes the quality of product from each analysis center, and then reprocesses to generate the combined product. The consistency of combined products is very important to the users of navigation and positioning, which directly affects the service performance of combined products. At first, this paper introduces the progress in iGMAS product combination. Then, the consistency of basic combined products (orbits, Earth rotation parameters, station coordinates, and clocks) is analyzed in details. And the precise point positioning tests are implemented to verify the consistency of combined products. Finally, some suggestions are given according to the test results of the present stage. The results of PPP test show that the static PPP coordinate daily repeatability of combined orbit/clock is at millimeter level. The standard deviation of combined orbit/clock single epoch PPP difference is comparable with the best AC orbit/clock solutions. The results of static and dynamic PPP also prove that the consistency of combined orbit/clock considering the consistency correction is improved significantly.