Analysis And Optimization Of Multipath Mitigation Technologies In GNSS

As the development of Global Navigation Satellites System, many error sources has been reduced by methods such as modeling and differential. Multipath error, which is corresponding to the signal modulation, receiving scenario and the software/hardware processing algorithms of the receivers, is difficult to eliminate in traditional ways. In that case, multipath error has been one of the main error sources that affect the positioning precision. Among various multipath mitigation methods, technologies that optimize the receivers'tracking loops play a vital role. Once designed, these technologies are less apt to multipath environments than other various multipath mitigation measurements, and the study on these technologies is always attracting researchers'attention.This paper firstly analyzes how the multipath signals are introduced, the characters of them and the influence on positioning. In the following, this paper introduces the multipath mitigation technologies which are practical for BPSK, BOC(1,1) and MBOC modulated signals, and simulates their performances. Then some conclusions are validated through the analysis of observed data.Specifically, this thesis mainly includes the following in detail:(1)Systematically studies the basic theory of multipath, including the characters and common mathematical models; introduces the typical GPS receiver's working process and analyzes the influences that multipath signals make on the tracking loops, which are the base of following study.(2)Studies the multipath mitigation technologies that are suitable for the BPSK modulated signals, including Narrow Correlator, Double-Delta, Code Correlation Reference Waveform; analyzes the working process of each technology and the factors that influence the performances, like channel characteristics and gate width; compares the performances under different conditions by analyzing the observed data.(3)Introduces the characters of new modulated signals, including their signal structures and auto-correlation functions; studies multipath mitigation technologies that are practical for BOC(1,1) and MBOC modulated signals, including conventional technologies and the new ones designed for new modulated signals; analyzes the multipath mitigation performances under different parameters and proposes the suitable parameters for receivers of different types.