Research On Spread Spectrum Signal Acquisition Algorithm And Implementation Technology In Broad And Narrow Band Interference

Direct Sequence/Frequency Hopping(DS/FH) hybrid spread spectrum communication system combines the advantages of direct sequence spread spectrum and frequency hopping spread spectrum, so it has a strong anti-interference ability and anti-interception capability. It has been applied in military communications and civilian communications widely. As DS/FH system applied in deep space detection and emergency communication, the acquisition algorithm of DS/FH is facing more challenges. In these applications, the received signal is extremely weak and subjected by various forms of interference. Therefore the paper researches the acquisition algorithm of DS/FH hybrid spread spectrum with broad and narrow band interference.At first, paper discusses the research background and significance, as well as the development present situation at home and abroad. Then paper research the DSSS signal acquisition algorithm and FHSS signal acquisition algorithm. After comparison and analysis, the DS/FH signal structure of DS chip and FH chip solid related is selected. And on this basis, a fast DS/FH hybrid spread spectrum acquisition algorithm is proposed.To further enhance the ability of the narrowband interference, paper researches the frequency domain narrowband interference suppression algorithm. Firstly, paper studies the application of the window functions, including: Influence of function window on spectrum leakage; the loss of SNR caused by window function; improvement of SNR caused by overlapping and window algorithm. Secondly, paper introduces several kinds of interference detection and suppression algorithm. Based on these algorithms, paper presents a three threshold interference suppression algorithm based on piecewise power statistics. The effectiveness of the algorithm is verified by MATLAB simulation. To further improve the algorithm broadband anti-interference ability, paper studies the high sensitivity acquisition algorithm, including: weak signal accumulation technology; code Doppler compensation; detection decision strategy of acquisition algorithm.At last, the FPGA platform is used to realize the DS/FH hybrid spread spectrum acquisition algorithm. The correctness of the design is proved by the experimental results.