Satellite Navigation Signal System Research And Design Under The Environment Of Multiple GNSS

In order to introduce a new service, all the countries are conducting research and design on the GNSS signal scheme. Introducing new service would cause severe compatibility problem since the L band is now heavily congregated by different GNSS signals. Design experience on L band GNSS signal is studied first and summarization is made, and then this paper presents a GNSS signal waveform appropriate to new band based on the study and summarization mentioned before. Specific work is done as follows:(1) The study of Interplex and signal waveform that are widely used for the current L frequency, mainly including BPSK, BOC and MBOC. Firstly, the evaluation models of navigation signal are established, and then the influence of part of the parameters on the GNSS signals performance is carried out based them. In this part the author mainly analyze the influence of subcarrier rate and code rate on the power code tracking precision, anti-multipath performance and compatibility of GNSS signals at first. Then, the author designed a three code-eight phase Interplex modulation method which solved the problem of fuzzy corresponding relation between eight different combinations of input signal values and six different phase quantity corresponding in traditional mutual multiplexing modulation method. Finally, in order to analyze compatibility of GNSS signal in L1 band, GNSS signals’ spectrum separation coefficients on L band are calculated. The design philosophy that new navigation signals must be compatible with existing business within frequency has been dug out, especially for avoiding military signal interference. Meanwhile it also highlights the importance of grabing the frequency resources in advance, which cumulative experience for satellite navigation signal design on new band.(2) In order to solve the problem of frequency spectrum resource, this paper put forward to realize the global satellite navigation in S band and design navigation signal for it. Firstly, the author analyzed the feasibility and necessity of S band in achieving global satellite navigation, and put forward a new modulation method--unilateral triple offset carrier modulation(UTOC). After the analysis of the performance of UTOC modulation signal, the presented study put forward two design schemes of S-BD signal. After a performance comparison, the results show that the design scheme based on UTOC modulation perform better in code tracking precision performance, anti-multipath performance and anti-narrowband interference performance than the design scheme based on BOC modulation under certain conditions. Thus, the author deemed that UTOC can be candidates as S-BD signal modulation mode.(3) In order to analysis compatibility between S-BD signals with existing signals in S band, this paper calculated carrier-to-noise degradation under the interference. The result shows that the design scheme based on UTOC modulation signal waveform was more suitable than the signal waveform design scheme based on BOC modulation for S frequencies of beidou satellite navigation system around the world.