Research Of Multi-targets Detection Technology For Linear Frequency-modulated Continuous Wave Radars Based On Millimeter Wave

Linear Frequency Modulated Continuous Wave(LFMCW)radar has the advantages of small size,low cost,low power consumption and high range resolution.It has gradually become an important sensor for commercial civilian use.Based on the millimeter wave LFMCW radar as the research background,this paper systematically studies the multi-targets pairing problem in multi-targets detection.The main contents are as follows:This article first introduces several modulation waveforms commonly used in the current LFMCW radar system,explains the principles of target range estimation and range resolution,speed estimation and speed resolution,and clarifies the range-speed coupling phenomenon existing in LFMCW radar.In multi-targets recognition and detection,symmetric triangle wave,variable-period triangle wave and trapezoidal wave have up-and-down sweep frequency,so there will be up-and-down sweep multi-targets pairing problem.From the perspective of LFMCW radar signal processing,it is divided into one-dimensional FFT(Fast Fourier Transform)processing and two-dimensional FFT processing.In the one-dimensional FFT processing,the spectral peak error row-column pairing method,the secondary mixing method,the distance and speed cross pairing method and the speed pairing method were studied for different modulation waveforms,and the pairing process was evaluated through MATLAB verification.Then,a pairing method of neighboring units is proposed based on the situation of symmetric triangle waves and road targets,that is,according to the principle that the distance units generated by the same target sweeping up and down are not more than two,the matching range is reduced,and fast and more accurate multi-targets pairing is achieved.The specific pairing The algorithm was verified by MATLAB.In the two-dimensional FFT processing,the sawtooth wave target detection and the symmetric triangular wave two-dimensional multi-targets pairing method are studied,and the variable-period triangular two-dimensional joint pairing method and the trapezoidal wave MTD(moving target detection)constant frequency velocity pairing method are proposed.For the variable-period triangular two-dimensional joint pairing method,firstly,the two targets of the same fuzzy channel after two modulated sweep two-dimensional FFT are paired separately.Pairing twice to get real target information;Trapezoidal wave MTD constant frequency velocity matching method,using the two-dimensional FFT of up and down frequency sweep to pair the same fuzzy channel,if the same fuzzy channel presents multiple targets,then the speed information is paired twice to realize multi-targets detection.Finally,MATLAB is used for digital simulation to verify the feasibility and effectiveness of the method.In this paper,a variety of multi-targets pairing methods are studied,and each multi-targets pairing method is verified and evaluated.At the end of the article,the LFMCW radar ambiguity function is studied and its characteristics are analyzed.