Monitoring Frequency Stability of GNSS Satellite Clock Utilizing Modified Technique Based on the In-Orbit Data of Phase Comparison

Clock plays a vital role in navigation satellites, and its design method has a high barrier to entry. The in-orbit anomalies of clocks of global navigation satellite system (GNSS) such as Galileo and Indian Regional Navigation Satellite System (IRNSS) indicate that the stable operation of clocks has the characteristic of high-risk. Thus, it’s of great importance to monitor the frequency stability of that. Currently, monitoring technique based on the in-orbit data of phase comparison between a master and a backup clock (IDPCMB) is able to solve traditional disadvantages of complexity, expensiveness, and unstable measurement accuracy; however, it obtains a poor accuracy when faced with condition of short-term stability. The primary purpose of this study is to design a modified IDPCMB monitoring technique, which is based on an analysis of Allan Variance from a different perspective, and can solve the drawbacks of traditional technique. The testing results show that the modified technique is superior to the traditional one.