Research On Signal Acquisition And Tracking Of Beidou Satellite Based On FPGA

With the increasing progress of modern science and technology,satellite navigation technology has penetrated into every corner of our life.In recent years,China's space satellite technology has been developing continuously.In the past ten years since the launch of the first Beidou 1 satellite in 2003,China has steadily developed and built its own global satellite navigation system Beidou satellite navigation system.Now,the construction of the Beidou satellite navigation system has been preliminarily completed,and the coverage of the Asia Pacific region has been achieved.The design of the receiver has become the top priority of the current scientific research.At the present stage,the Beidou satellite has been in the initial stage of development,and the accuracy and speed of the receiver part of the ground end still needs great improvement.How to improve the accuracy and speed of the Beidou navigation satellite receiver has become a major problem that needs to be tackled at the present stage.The baseband signal processing part of the receiver has a great influence on the accuracy and speed of the satellite positioning receiver.Therefore,the research on this part has become the focus of the research in all walks of life in China.This thesis mainly focuses on the internal baseband signal processing of Beidou satellite navigation system receiver.Beidou satellite receiver receives the Beidou satellite signal,and it is converted into intermediate frequency signal after processing by radio frequency unit.The intermediate frequency signal enters the digital receiver channel.The capture and tracking of satellite signals are mainly carried out in this channel,and the navigation message is demodulated during the tracking process.First of all,the principle of signal acquisition algorithm is introduced,and the traditional acquisition algorithm,serial time domain sliding capture algorithm,parallel frequency acquisition algorithm and parallel code phase acquisition algorithm are introduced in succession.The advantages and disadvantages of these algorithms are compared,including the capture time,the amount of resource usage,and the complexity of the algorithm.Secondly,the tracking algorithm after the capture algorithm is analyzed and analyzed.The main principle is that the signal capture can be real-time and dynamic using the principle of phase locked loop.Finally,the serial sliding acquisition algorithm is simulated and tested under the existing conditions.The experiment part includes the realization of Beidou satellite signal simulation in matlab.According to the principle of pseudo code generation,37 Beidou ranging codes are implemented,and the satellite signals are captured.The simulation results show that the satellite signals can be correctly captured,and the Doppler frequency shift and the phase shift of the code phase can be correctly captured.Then,in order to combine with the hardware,this paper attempts to build the key modules in FPGA and simulate it.The main modules include pseudo code generation module,local carrier generation module,intermediate frequency signal generation module,mixer module and correlator module.The simulation results can reflect that the design has reached the basic goal.