超声回波信号解调及其包络相关时延估计算法

互相关函数法是脉冲法超声测距中最常用的时延估计算法,但窄带超声回波信号的振荡特性导致它们的相关函数在峰值位置近似作等幅振荡,从而为精确搜索相关函数的峰值带来困难,所以有必要对相关函数包络的峰值进行搜索.首先分析了超声回波信号解调的常规算法,然后提出了基于FFT的直接提取相关函数包络的快速算法.仿真与实验研究表明,该方法能精确提取相关函数的包络,在不增加计算量的情况下精确搜索到相关函数的峰值位置.

Algorithm of TDE Based On Ultrasonic Echo Demodulation and its Envelope Correlation

Cross-correlation is the common arithmetic in pulse-echo ultrasonic measurement distance. Because the narrow-band echoes are oscillatory, the cross-correlation is high oscillatory with similar amplitudes around the peak and it becomes difficult to find the actual maximum. It is necessary to search the peak of the envelope of the cross-correlation. Firstly, the conventional algorithm of ultrasonic echo demo dulation is analyzed, then the fast algorithm of extracting directly the envelope of the cross-correlation is presented. It is proved by simulation and experiment that the envelope of the cross-correlation can be extracted and the peak can be found exactly by this method.