Research On Millimeter Wave Short-range Target Detection Algorithm

With the background of short-range target detection,this paper focuses on algorithm of millimeter-wave short-range target detection,including the principle of range and speed measurement of several systems radar,multi-target detection algorithm,constant false alarm rate processing algorithm,system hardware and software design and experiments,and other aspects.The main research contents are as follows.(1)Explain the reason of choosing continuous wave as the short-range target detection system.By building a mathematical model of beat signal from a single target,the range and speed measurement of constant frequency continuous wave,triangular wave linear frequency modulated continuous wave(LFMCW),frequency shift keyed continuous wave,and triangular wave and sawtooth wave LFMCW radar with multi-period accumulation are systematically described.The principles of LFMCW are used to provide the theoretical basis for the algorithm research in the later chapter.The single-period triangular wave LFMCW radar and the multiperiod triangular wave LFMCW radar are studied separately with the help of ambiguity function tool,and the performance of LFMCW radar for range and speed measurement is analyzed by the derivation of equations.(2)The 2D FFT multi-target detection algorithm based on sawtooth wave and triangular wave LFMCW is studied and analyzed.The 2D FFT multi-target detection algorithm based on triangular wave LFMCW is studied in a focused manner.For the case that the ambiguous Doppler frequency is corresponding to multiple targets,the velocity information of the targets obtained by pairing the center frequencies of the upper and lower sweep frequency bands is matched one by one using the relationship between the Doppler frequency and the ambiguous Doppler frequency of the target,so as to eliminate the false targets and obtain the distancevelocity information of the real targets.The one-dimensional FFT multi-target detection algorithm based on triangular wave and trapezoidal wave FMCW is studied and analyzed,and a multi-target detection improvement algorithm based on variable-period trapezoidal wave FMCW is studied for the problem of large computation of the multi-target detection algorithm based on variable-period trapezoidal wave FMCW,the essentially of which is to perform tolerance matching of combined targets in the distance dimension to eliminate more false targets,so as to achieve the purpose of improving the efficiency of the algorithm.(3)Several Constant False Alert Rate(CFAR)processing algorithms are studied and analyzed,focusing on CA-CFAR,SO-CFAR and GO-CFAR based on mean level,OS-CFAR based on ordered statistics,and VI-CFAR which is one of adaptive CFAR detectors.Through simulation experiments.the detection performance of several CFAR detectors mentioned above is analyzed and verified in different background.For the problem that the detection performance of VI-CFAR decreases when the number of interfering targets in the front and rear sliding windows increases,the algorithm is improved by adding ACMLD-CFAR.The improved VICFAR detector with good detection performance in multi-target background is demonstrated by simulation.(4)The software and hardware design of the signal processing module of the short-range target detection system is introduced.The hardware part mainly includes the design of DSP module,ADC module and signal modulation module,and the software part mainly includes the implementation of multi-target detection and constant false alarm rate processing algorithms.Then the system is tuned and tested,and field experiments are conducted to analyze the algorithm performance.The analysis of the experimental data confirms that the algorithm in this paper is effective and ensures a good ranging accuracy of the close range target detection system.