Research On Principles And Compatibility Of GNSS Signals

Global satellite navigation system(GNSS) is a unified title of global position system(GPS), GLONASS system and Galileo system, and also on behalf of the enhanced position system. The members also includes the under development systems such as our Beidou navigation system, Japan’s Quasi-Zenith system and the Indian Regional Navigation system. As the most critical part of the navigation system, the signal principles determine the innate performance, and has a decisive impact on compatibility between different systems. Thus, both in the process of building a new system or the modernization of GPS, the structural design is focus on the signal constitution. Besides, due to the rapid development of GNSS, and the International Telecommunication Union restrictions on navigation signal bandwidth, compatibility issues between various systems are bound to exist. As the prerequisite for coexistence and interoperability of the satellite navigation systems, signal compatibility is also the focus of international frequency coordination.This thesis is divided into two parts. In the first part, the GNSS signal principle and method for evaluation the compatibility are studied. In the second part, different signals in the BOC type are researched based on waveform design, and a constant envelope of navigation signal called PS-Alt BOC is put forward, which inherited from the standard Alt BOC modulation. And time domain and frequency domain model is established, the modulation method is also designed. And finally analyzed the performance of PS-Alt BOC in the aspects of out-of-band loss, code tracking ability, anti-multipath performance, anti-jamming performance and compatibility performance, assuming used in Beidou B2 band.The main contribution of this thesis and research are as follows:The signal constraction of GPS, Galileo and Beidou are analyzed in the view of signal multiple choice, frequency planning, pseudo code design, signal waveform design and pilot signal design. And the GNSS signal compatibility is studied. The BOC modulation, Alt BOC modulation and TD-Alt BOC modulation are analyzed in detail.Made the foundation for the establishment and construction of new navigation signal for Beidou system.Established a new signal model with constant envelope called PS-Alt BOC, solvethe non-constant envelope problem of standard Alt BOC modulation signal. Analyzed the performance of PS-Alt BOC modulation in the aspects of out-of-band loss, code tracking ability, anti-multipath performance and anti-jamming performance. Analyzed the compatibility performance between GPS system Galileo system and Beidou system,assuming that PS-Alt BOC(15,10) applied to Beidou B2 band. The results provide the theoretical support for the new signal design of Bedou system.