Design And Implementation Of LFMCW Radar Signal Processing System

Linear frequency modulated continuous wave(LFMCW)radars are widely used in the field of active target detection because of their small size,high ranging and speed measurement accuracy,no ranging blind spots,and low cost.In recent years,with the opening of the low-altitude field,the "low,slow and small" aircraft market represented by UAVs has entered a period of rapid development.Effective monitoring and control of UAVs has become an urgent problem to be solved.This paper uses the LFMCW system radar scheme to detect UAV targets,focusing on theoretical research and simulation analysis of key signal processing algorithms such as Doppler processing,clutter suppression,and constant false alarm detection,and is based on a hardware system with FPGA as the core.The platform completed the design and implementation of LFMCW signal processing algorithm.The main contents of this paper are as follows:1.The principle of sawtooth wave LFMCW radar signal and the method of ranging and speed measurement are studied,and the LFMCW radar signal processing system scheme and key parameters are designed according to project requirements.2.Deeply analysis of the moving target indication(MTI)technology in Doppler processing and the principle of using the velocity dimension FFT in the two-dimensional FFT to implement the doppler filter group.The algorithm is simulated to obtain the influence of the system design parameters on the algorithm performance,combining the target velocity characteristics,the velocity dimension FFT points and other important parameter pairs,which is used to guide the actual system design.Aiming at the shortcomings of traditional constant false alarm detection and variable index constant false alarm detection in complex clutter environments,the improved algorithm of variable index constant false alarm detection is studied,and combined with the requirements ofengineering realization,it is optimized and effectively improve the target detection algorithm's ability to deal with complex clutter environment.3.Implement the LFMCW radar signal processing system on the FPGA hardware platform,and verify the feasibility of the LFMCW radar signal processing system.First,the overall framework and hardware design of the system design are given,and then in response to the requirements of real-time signal acquisition,a signal acquisition module based on the ping-pong buffer structure is designed,and the method of matrix transposition using DDR is used for preprocessing of MTI and two-dimensional FFT,Which makes it more convenient and simple to perform MTI and two-dimensional FFT processing on the signal.Finally,the key modules and system functions of the system are verified to prove the effectiveness of the system.