Research On Fast Acquisition Technology Of Inter-Satellite Link Signal In Navigation Constellation

In the inter-satellite link spread spectrum communication system,it's a common method to packetize and transmit data using a synchronous head fragment to guide the data segment.In order to meet the requirements of stable transmission and reception under low SNR conditions,the sequence of the spread spectrum code is required to have a sufficient length to improve the capture probability.The long pseudo random code generally has a higher code rate and the far-longer single-cycle duration,and these characteristics bring it strong anti-interference and confidentiality.on the one hand,the long pseudo random code can meet the requirements of the burst spread spectrum communication system.But on the other hand,it causes great difficulty for direct fast capture.So if we are talking about long code direct capture,it1 s important to make sufficient optimization of the algorithm's calculation amount,capture accuracy,capture speed and other factors.Based on this problem,this thesis mainly studies and discusses the improvement and implementation of the long pseudo code capture algorithms,and solves the following key technical problems:(1)Analysis of the key characteristics of long code in capture,and summarize the advantages and disadvantages of the classic capture method in dealing with long code capture problems;(2)Using the partial correlation parallel phase method to complete the fast capture of the long code,and analyzing the algorithm flow and the capture effect,according to which the fast and high gain capture criteria meeting the project requirements are established;(3)According to the characteristics of the capture system,the implementation scheme of the long code fast capture system on the Xilinx UltraSccale+ platform is given,and the working mode and process of each main module are analyzed in detail.At the end of the thesis,the prototype of the long code capture system is given.The feasibility and effectiveness of these techniques are proved by constructing simulation and actual test,in order to provide certain reference value for the subsequent receiver system development.