Study On The Signal Process Technology Of Pseudo-random Code Phase Modulation And Sine Frequency Modulation Combined Distance System

The pseudo-random code phase modulation and sine frequency modulation combined distance system works by making full use of the remarkable auto-correlation characteristics of pseudo-random code. Owing to its precise distance measurement ability and excellent anti-jamming performance, it has been proved to be one of the important development directions of distance system. So, it has important theoretical guiding significance for the research and application of the pseudo-random code ranging system by studying the signal processing technology of the combined system.In this paper, the relevant principle of the signal process on the pseudo-random code phase modulation and sine frequency modulation combined distance system is introduced in detail. Then, the characteristics of the pseudo-random code signal, pseudo-code phase modulation signal, sine FM signal,and pseudo-random code phase modulation and sine frequency modulation combined signal is analyzed detailedly in their time domain and frequency domain. The thesis is based on the detailed analysis of the operating principle of pseudo random code phase modulation and sine frequency modulation combined distance system, analyzing and deducing the mechanism process of transmitting signal and the echo signal in the system, discussing main parameters choice of the combined distance system, analyzing the detecting distance capacity, building receiver model of the combined distance system. In the conditions of Gauss white noise jamming,noise amplitude modulation (NAM) jamming and noise frequency modulation (NFM) jamming,the overall signal to jamming ratio (SJR) gain of the receiver output signal is reduced detailedly in the thesis.The anti-noise jamming performance, anti NAM jamming performance and anti NFM jamming performance of the combined system are analyzed deeply in terms of the overall SJR gain. At last, the thesis makes full use of MATLAB/Simulink to complete the simulational modularization design. And according to the design and simulation of pseudo random code generating circuit,the demodulation circuit,and digital correlator circuit,the function of the signal procession is also accomplished.