Research And Realization On Beidou Pseudolite Acquisition Algorithm

With the development of economy, the requirement about precise positioning and management becomes strong nowadays. Demand on accurate positioning is increasing. Now many countries plan to build their own satellite navigation system. Bei Dou Navigation Satellite System is developed by our country. The system has a broad prospect in the field of military and civilian areas. The pseudolite technology developed from navigation technology attracts more and more attentions. This thesis puts forward an improved method of acquisition through researching the traditional acquisition algorithms, and it is applied to the pseudolite system. The new acquisition method is realized on FPGA platform. The main contents of the thesis are as follows:This thesis introduces the basic structure and related features of Bei Dou signal, and provides related simulations. Then it introduces three kinds of traditional acquisition algorithms through the formula derivation, which provides basic theories for the improved acquisition method. Then the thesis provides the comparison of the three kinds of algorithms about the time-consuming and simple resource requirements analysis. The advantages and disadvantages of them are analyzed. At the end of the chapter, multipath effect is analysed.According to the practical situation, this thesis puts forward the improved acquisition method, which is refered to the traditional algorithms. It includes partial integration and improved coherent integration. The improved method describes the specific implementation principles and methods of the improved acquisition algorithm. It also describes the parallelism about the new acquisition method. The thesis puts forward the method of re-acquisition which applies to the Bei Dou pseudolite system. It builds the simulation platform based on MATLAB, and uses the software signal generator to generate the satellite signal as a test vector for simulation platform. The thesis also compares the improved algorithm with traditional algorithms, and verifies the results. After the comparison, it comes to a conclusion that the improved algorithm can achieve quick acquisition.This thesis establishes the acquisiton system with the improved algorithm on the hardware platform. The hardware platform is based on FPGA + ARM architecture. It first discusses the plan about parameter interaction between the FPGA and ARM. The acquisition system is introduced in various parts of the hardware structure and module design. This design completes the design of communication interaction modules between the FPGA and ARM, and local related channel modules, coherent integration modules, re-acquisition modules. This topic uses the test vector to simulate the design results, and verify the validity of the modules’ results. At the end of the thesis, it analyses the consumption of hardware resources of the system. This thesis also compares the improved algorithm with traditional algorithms in consumption of hardware resources, and comes to a conclusion that the improved algorithm can achieve the requirement of the pseudolite system.