The Orbit and Clock Combination of iGMAS Analysis Centers and the Analysis of Their Precision

摘要

Several analysis centers (AC) and a product integration and service center have been built by the international GNSS continuous Monitoring and Assessment System (iGMAS) currently. Product integration and service center (ISC) analyzes the quality of product provided by analysis centers, and then reprocesses to generate a combined product. The orbit and clock solutions are the vital products of ISC and important foundation data for satellite navigation and precise point positioning (PPP). First of all, this paper introduces the principles, methods and mathematical models of orbit and clock combination. Then, the precision of combined products and analysis centers' products with respect to the IGS final is compared and analyzed. Furthermore, the PPP tests are implemented to verify the accuracy and reliability of combined orbit and clock. The results show that the RMS of combined orbit and clock with respect to referenced solutions is better than the most analysis centers. The static PPP tests prove that the combined orbit/clock consistency is maintained at millimeter level. The standard deviation of single epoch PPP difference using combined orbit/clock is comparable to the best AC orbit/clock solutions.