用超声测量火箭发动机包覆层厚度时，当包覆层较薄时检测回波信号会出现时域混叠。为此提出一种时间延迟估计的新方法。该方法能对修正的检测信号能量谱的对数微商求逆傅里叶变换。实验结果表明，该方法能准确估计出时域混叠信号的延迟时间。提高了火箭发动机包覆层厚度测量精度。

When measuring the cladding thickness of rocket motor by ultrasonic means, the obtained echoes of the thin cladding will overlap in the time field. Based on the characteristics of overlapped echoes, a new method for time delay estimation was presented. The method consisted in taking the envelope of the inverse Fourier transform of a corrected measured signal. Experimental results showed the method could estimate the delay time of the overlapped signals accurately. It improved the measuring precision of the thickness of rocket motor cladding.