Abstract:

In the signal generation, emission, transmission and receiving processes of the global navigation satellite system (GNSS), due to some unpredictable anomalies or effects, there are various abnormalities that would affect GNSS signal quality. Consequently, those unpredictable anomalies and effects received by users would influence the position, velocity and time (PVT) performance of the GNSS. By monitoring and assessment of GNSS signal quality, it would be possible to detect signal distortions and warn the users as soon as possible, thus guaranteeing a safe and efficient use of the GNSS, especially for civil aviation and maritime affair users. However, for the monitoring and assessment of a variety of abnormal GNSS navigation signals, there are no comprehensive and systematic research results yet, and no real-time or quasi real-time automatic identification and mechanism for signal distortion analyzing at present. The idea of establishing a GNSS signal distortion model is introduced. To detect GNSS signal distortions caused during the processes from signal generation to signal receiving, and to further analyze their impacts on the service performance of the GNSS, a relatively complete mathematical method is proposed through simulation and data verification. Besides, the generation mechanisms and characteristics of GNSS signal distortions are analyzed in detail, and based on that, the influences of GNSS signal distortions on signal quality assessment and user positioning are given both in qualitative and quantitative methods. The achievements in this paper could be used as a valuable technical reference for automatic identification and locating of GNSS satellite faults. In addition, it could also be a good reference for satellite signal generation designers in signal designing and optimizing.