基于SESTH的线性调频连续波激光雷达信号时延估计

Time delay estimation of linear frequency-modulated continuous-wave lidar signals via SESTH

针对线性调频连续波(Linear frequency-modulated continuous-wave,LFMCW)激光雷达低信噪比下目标回波信号参数难以提取的问题,提出了一种基于SESTH(Synchroextracting S transform based on Hough transform)变换的信号时延估计方法。首先,融入Hough变换,构建了Chirp信号的SESTH变换模型。然后,推导出Chirp信号的初始频率和调频率参数估计模型。最后,利用LFMCW激光雷达发射信号与回波信号的时频特性,构建Chirp信号的时延估计模型,有效解算出目标与雷达间的相对距离。为验证本文算法的有效性,进行了仿真对比分析。结果表明:本文SESTH算法在时延为4.34μs时,相对误差最小值为3.191×10^(-6);在SNR=-6~25 dB情况下,相对均方根误差最小值为0.01465,且对目标回波信号执行一次仅需0.0499 s。

The parameters extraction of the target echo signal of linear frequency-modulated continuouswave(LFMCW)lidar is more difficult under low signal-to-noise ratio(SNR).To solve this problem,a signal time delay estimation method based on synchroextracting S transform based on the Hough transform(SESTH)is proposed.Firstly,integrating Hough transform,the SESTH model of a Chirp signal was constructed.Then,the parameter estimation models of initial frequency and frequency modulation rate of the Chirp signal were derived.Finally,using the time-frequency characteristics of the LFMCW lidar transmitted signal and echo signal,the time delay estimation model of a Chirp signal was constructed,and the relative distance between a target and the lidar was effectively calculated.In order to verify the effectiveness of the algorithm,simulation comparative analysis were carried out.The results show that the minimum relative error value of the proposed SESTH is 3.191×10^(-6) when the time delay is 4.34μs;the minimum relative root mean square error value is 0.01465 in the case of SNR=-6~25 dB,and only 0.0499 s is consumed to execute the target echo signal once.