Monitoring and evaluation algorithm of GNSS signal in space availability

In civil aviation and other navigation application fields, the availability of Global Navigation Satellite System (GNSS) in Signal in Space (SIS) is a key indicator to evaluate the performance. In this paper, the SIS availability of Global Positioning System (GPS) and BeiDou Navigation Satellite System (BDS) are evaluated and analyzed. The model of satellite availability algorithm is constructed based on the Markov process, with its reliability investigated. Moreover, the evaluation algorithm of constellation availability is developed. Based on the evaluation models, the performance of GPS SIS and BDS SIS is evaluated by using the measured data, respectively. Combined with the availability standard of GPS Standard Positioning Service (SPS) performance standards and BDS Signal In Space Interface Control Document (Version 2.0), the proposed evaluation models of SIS availability are effective and the performance of GPS SIS and BDS SIS conform the availability of performance standards, respectively. Meanwhile, the results are instructive for the study of the availability performance monitoring and the evaluation of global BDS.