Research And Implementation Of FMCW Laser Ranging Signal Processing Technology

Laser ranging technology has been widely used in the national economy and military fields.Continuously improving the accuracy of ranging is the long-term research direction and main content in the field of ranging technology.Taking the frequency-modulated continuous wave laser ranging system as the analysis object and improving the ranging accuracy as the research goal,the following research work is carried out by theoretical analysis,simulation verification and experimental verification to solve the problem of inaccurate frequency extraction of difference frequency signal and affect the ranging accuracy:1.Based on the analysis of the principle of frequency modulation continuous wave laser ranging,taking FMCW as the analysis object,the important factors affecting the ranging accuracy are theoretically analyzed,and the accurate extraction of the frequency of the difference frequency is clarified as the research goal of this paper.The commonly used Fast Fourier Transform(FFT)spectrum analysis method for frequency extraction and the noise generated by the device and channel during the system implementation process are analyzed and studied.2.Aiming at the problem of channel and device noise affecting the ranging accuracy,a wavelet threshold denoising scheme is designed.The thermal noise and shot noise generated by the communication channel and various devices during the implementation of the system were analyzed and classified as Gaussian white noise,and the wavelet threshold denoising method was designed to filter the obtained difference frequency signal,and the effectiveness of the denoising algorithm was verified by MATLAB simulation,and the simulation results showed that the signal-to-noise ratio before denoising was 5.2828 and 18.4349 after denoising,and the denoising effect was good.The algorithm is described using the Verilog language and its functionality is verified by Vivado platform simulation.3.Aiming at the leakage problem caused by FFT transformation to obtain the frequency of the difference frequency after direct truncation of the signal,this paper studies the relevant theory of full-phase spectrum analysis,and proposes to use the comprehensive phase difference spectrum correction algorithm based on the traditional FFT and full-phase FFT spectral analysis methods to process the difference frequency signal of the frequency-modulated continuous wave laser ranging system to extract the difference frequency signal frequency.The algorithm is described using Verilog language,and its function is verified by Vivado platform simulation,and the simulation results show that the algorithm can reach a measurement resolution of 15.2Hz in the measurement range of 1～1000KHz,which meets the needs of the system.4.Based on the above theoretical research,the external cavity tunable laser is used as the system light source,and the frequency-modulated continuous wave laser ranging system for FPGA is designed and built,and the functional verification of the system is carried out,and the effectiveness of the information processing scheme designed in the paper is proved by the analysis of experimental results.