Optimized Space  Station CV Method and Its Differences from GNSS CV

Abstract There will be better atomic clock system and micro-wave time comparison link in the near earth space station, like Chinese Space Station and European ACES(Atomic Clock Ensemble in Space) system, than those in the GNSS(Global Navigation satellite System) satellites. Therefore, the space station common-view (CV) will realize more accurate time comparison than GNSS CV in theory. But due to the orbit characteristic of the space station, there are some limitations if traditional GNSS CV time comparison method is applied to the space station. In order to solve these problems, the GNSS CV method is optimized and the method that is appropriate for the space station is proposed. First, the basic CV principle is analyzed, and the delay items which are needed to be considered for GNSS and space station CV are compared and analyzed. Then, the differences between GNSS and space station CV are studied, and the influences of orbit error on these two CV methods are analyzed in detail. The GNSS CV method is optimized to be fit for the space station next. Finally, the performance of the optimized method is validated by simulated experiments. The simulation results show that the space station time comparison accuracy of several tens of picoseconds can be obtained by the optimized method. Furthermore, the problem of CV blind area is solved by the optimized method effectively.