Research And Implementation Of GNSS Receiver High Dynamic Weak Signal Acquisition Algorithm

With the gradually mature of the satellite navigation industry,navigation receivers are gradually used in various industries.High dynamic receivers have also received much attention due to their applications in the military field,and the demand for high dynamic receivers with high sensitivity performance has gradually increased.For the receiver,signal acquisition is the key prerequisite for the receiver to implement baseband signal processing and navigation solution.High dynamic scenes require fast acquisition modules,and weak signal scenes need to increase the accumulation time to obtain better sensitivity,how to balance the contradiction between the two in practice and improve the performance of satellite navigation signal acquisition under high dynamic environment is of great significance.The main research contents and results of the paper are as follows:First,the paper introduces the characteristics of satellite navigation signals,based on the universality of the satellite signal design,the four frequency bands selected for the project are BDS B1 I,BDS B3 I,GPS L1,and GLONASS L1.Starting from the function and basic principles of signal acquisition,by comparing the performance of the three basic algorithms in terms of performance and hardware resource consumption,PMF-FFT acquisition algorithm is selected as the basic algorithm for the subject design.At the same time,the influence of high dynamic weak signal scene on signal acquisition is analyzed.Secondly,in order to reduce the impact of scallop loss on acquisition performance,the method of zero-filling the FFT input is used to suppress the scallop loss of the acquisition algorithm.Aiming at the problem of poor acquisition performance of the acquisition algorithm in high dynamic weak signal scenarios,a dual-parallel PMF-FFT acquisition algorithm is proposed,this algorithm not only expands the search of the acquisition module in the frequency dimension through the dual-carrier parallel acquisition method The range also increases the acquisition speed by 10 times through the parallel acquisition method of 10 pseudo-codes,which improves the dynamic performance and acquisition speed of the acquisition algorithm.At the same time,in order to improve the sensitivity of the acquisition algorithm,research and compare the integration methods of weak signal acquisition,and choose the differential coherence method as the integration method of the acquisition module,this method is very suitable for high dynamic scenes where the coherent integration should not be too long,and improves the sensitivity of the capture algorithm.Thirdly,in order to complete the hardware implementation of the acquisition algorithm and build the acquisition module test platform,the overall scheme and communication scheme design were completed based on the Zynq 7000 platform.The Verilog HDL hardware description language was used to complete the compilation of each sub-module of the acquisition system,and the function of each sub-module was verified by Vivado simulation.The overall hardware circuit design of the acquisition module is completed through the series construction of each sub-module and the design of the acquisition judgement and channel switching controller.At the same time,aiming at the problems of hardware resource occupation and acquisition efficiency,the design of the acquisition strategy and re-acquisition strategy of the multi-band common acquisition module is completed.Finally,in order to verify the feasibility of the acquisition algorithm and the correctness of the design of the acquisition module,the performance test and functional verification of the acquisition module were completed.The test results show that the acquisition module basically meets the design goals in terms of acquisition speed and acquisition sensitivity performance.At the same time,the acquisition sensitivity has been improved to a certain extent compared with high dynamic receivers on the market.Tests on other functions of the receiver also show that all functions of the receiver are normal,the acquisition strategy design is correct and effective,and the acquisition system has certain practicability.