Research On Configurable Multi-constellation GNSS Signals Synchronization Technology

With the rapid development of the four Global Navigation Satellite Systems, multi-constellation navigation receiver has become one of the hot research areas of navigation. Compared to the traditional single-system navigation receiver, multi-constellation navigation receiver has better positioning accuracy, velocity measurements and timing performance and better environmental adaptability, etc. However, the most important issue faced by the multi-constellation receiver is how to complete synchronization progress of different navigation signals properly and reliably. The synchronization of GNSS signals is devided into two steps: acquisition and tracking. In this paper, acquisition and tracking algorithms for GNSS signals are studied in detail, and some improved algorthims are proposed. Besides, configurable acquisition and tracking schemes based on software platform are designed, and a software for multi-constellation signals synchronization is developed. The main content of the research and innovation are as follows:1. Four GNSS signals, i.e., BDS B1 I, GLONASS L1, GPS L1 C and Galileo E1 B signals are introduced. Modulation, PRN code, autocorrelation function and some other characteristics are studied in detail, and autocorrelation functions of different signals are analyed and compared, the effect on acquisition and tracking introduced by the difference of the signals also has been pointed out.2. Coherent CBOC type receiver of the SCPC technique for Galileo CBOC signal is proposed. The proposed method can exploit all the composition of Galileo CBOC signal, thus compared to noncoherent CBOC type receiver, BOC(1,1) type receiver of the SCPC technique and classic BPSK-like technique, the proposed method has the best performance. Besides, coherent joint data-pilot acquisition strategy for GPS L1 C signal is proposed. Theoretical analysis and simulation results both show that coherent joint data-pilot acquisition strategy outperforms than single-channel acquisition strategy.3. The traditional tracking algorithm for BPSK signal and unambiguous ASPeCT tracking algorithm for CBOC signal are analyzed, simulation results demonstrate the effectiveness of the traditional tracking algorithm for BPSK signal and effectiveness of unambiguous ASPeCT tracking algorithm for Galileo E1 B and GPS L1 C signals.4. The difference of acquisition algorithms and difference of tracking algorithms for different navigation signals are analyzed, the configurable acquisition scheme and configurable tracking scheme based on software platform are designed. The acquisition, tracking parameters and algorithms can be adjusted according to different navigation signals in these schemes. These schemes utilize module reused technology to acquire and track different navigation signals effectively, while with low complexity, short development cycle and low cost.5. A software for multi-constellation signals synchronization has been developed based on the configurable acquisition and tracking schems. The framework of the software is designed and the detail design and realization of the software is implemented. Test results show that the software is capable of acquiring and tracking different navigation signals correctly, which demonstrates the feasibility of the configurable acquisition and tracking schemes designed in this paper.