The Application Research Of Spread Spectrum Technology In LPI Radar

Nowadays, the application of Electronic Support Measure (ESM) receivers, Radar Warning Receivers (RWR) and especially ARM forms a serious menace to radar's existence and The Low Probability of Interception (LPI) radar just appears under this circumstance. LPI radar attempts to use various techniques to make radar signal not be intercepted by intercept receivers. With adopting spectrum-spread technology to the LPI radar, the radar has an excellent ability of LPI and counter electronic countermeasures of electric interference. But it also has other problems in practice.This paper focus on these problems and discusses the possibility of using Pseudo-Random Code Phase Modulated (PRCPM) technology in measuring high speed target .At first the basic principle of the m series is given,then a Doppler pretreatment method is given. Through utilizing the shift multiplication characteristics of m series, this kind of radar system eliminates the bad effect of Doppler frequency .In theory, the Doppler tolerance of the radar system can reach the half of the code rate with proposed echo pretreatment method in this paper. As a result, it is suitable for the ultra-high-speed target detection. Secondly, based on the methods of fast acquisition for code, a new algorithm with two-dimensional FFT in order to increase the speed of signal processing is proposed. In this way, it can achieve accuracy speed and range of the target. After establishing the model of Intermediate Frequency Direct Sequence Spreading Spectrum (IF DSSS) receiver, comparing and analyzing several conventional code acquisition methods, code and carrier two-dimension fast acquisition scheme based on two-dimension FFT is proposed. Finally, the situation for two targets is analyzed.At last, the result shows that the method of this paper is effective by simulation.