多段同频正弦信号频谱融合的LFMCW雷达测距算法

LFMCW radar range algorithm based on spectra fusion of multi-section co-frequency sinusoids

为提高线性调频连续波(LFMCW)雷达的测距精度,提出一种多段同频正弦信号频谱融合的测距算法。首先,通过易于工程实现的间断采样方式,将LFMCW雷达若干规则区差拍信号采样为多段同频正弦信号,有效避开不规则区;其次,构造加权因子对多段规则区差拍采样信号频谱进行加权积累,得到最优加权积累频谱;然后,将多段规则区差拍采样信号的最优加权积累频谱和其累加频谱进行相关运算,得到频谱相关谱;最后,谱峰搜索频谱相关谱,实现差拍信号频率的精确估计,从而实现LFMCW雷达的高精度测距。仿真和现场实验结果表明,在5～30 m的测距范围内,该算法频率估计的平均绝对误差约为FFT+CZT法的1/5,测距精度始终保持在1 mm以下,其平均测量误差约为DEVON L80手持激光测距仪的1/3,约为基于FFT+CZT的测距法的1/5。

To improve range precision of LFMCW radar, an algorithm based on spectra fusion of multi-section co-frequency （MSCF） sinusoids is presented. To avoid sampling in the abnormal-areas, the intermediate frequency signals in the normal-areas are first converted into MSCF sinusoids by an easy sampling method. The optimization weighted- accumulation（OW-A） slypeetrum is gained through weighted-accumulation spectra of the MSCF sinusoids by desig- ning weighted factors. The correlation spectrum is constructed by correlating the OW-A spectrum and the accumulation spectrum of the MSCF sinusoids. Consequently, the exact frequency estimation of the intermediate frequency signal can be obtained through spectral peak searching of the correlation spectrum,and high precision range of LFMCW radar can be achieved. Simulation and experiment results demonstrate that the mean absolute error of frequency estimation of the proposed algorithm is about 1/5 times of the FFT ＋ CZT method. The proposed algorithm range precision can be below 1 mm in the range from 5 m to 30 m. The mean range error is about 1/3 of the hand-hold distance finder,which is 1/5 times the range measurement method based on FFT ＋ CZT.