Simulation research on coherent detection of pulsed laser based on LFM

Aiming at the problem that the laser coherent detection system is easy to be annihilated in the noise in the long-distance and complex environment, resulting in the system unable to extract effective information, In this paper, the pulse compression theory and matched filter principle are analyzed, and a target high-precision matched filter LFM system model suitable for laser coherent detection is proposed, by transmitting a linear frequency modulation signal, combined with the matched filter algorithm to process the echo signal, realizes the target distance solution under the condition of low signal-to-noise ratio. At the same time, the influence of FM bandwidth on the multi-target extractionability under different SNR is studied, and the FM bandwidth-ranging accuracy model is established. Compared with the ordinary windowing algorithm, by increasing the system FM bandwidth, it can be effective in extremely low signal-to-noise ratios. Extract multi-target distance values. The simulation results show that under the condition of -40 dB signal-to-noise ratio, setting the frequency modulation bandwidth to 4 GHz can effectively achieve multi-target detection, and the ranging accuracy can reach 4.5 mm.