中文摘要：

水下动目标径向速度造成的回波和样本之间失配导致匹配滤波器对于线性调频（LFM）信号的检测性能下降。利用分数阶傅立叶变换对LFM信号的聚焦特性，提出一种基于离散分数阶傅立叶变换的水下动目标LFM回波检测算法。该算法与零速样本匹配滤波检测算法相比受目标径向速度影响较小，并且理论分析表明在目标回波存在的情况下，这两种算法输出的峰值位置之间存在数学关系。利用该数学关系本文算法同样可以估计目标距离。仿真和实验数据分析表明：本文算法在强混响噪声背景下对于径向速度未知动目标LFM回波的检测性能优于或相当于零速样本匹配滤波。

英文摘要：

The mismatch between echo and replica caused by underwater moving target（UMT）＇s radial velocity degrades the detection performance of matched filter （MF）. By using the focusing property of fractional Fourier transform （FRFT） to linear frequency modulation （LFM） signal, a discrete fractional Fourier transform（DFRFT）-based detection algorithm for UMT＇s LFM echo was proposed. The algorithm is less affected by target＇s radial velocity compared with the other MF detection algorithm utilizing zero radial velocity replica（ZRVR）, and the mathematical relation between the output peak positions of these two algorithms is present in the case of existence of target echo. The algorithm can also estimate the target distance by using this mathematical relation. The simulation and experiment data analysis show that the algorithm＇s detection performance is better than or equivalent to that of the other MF detection algorithm utilizing ZRVR for the LFM echo of UMT with unknown radial velocity under reverberation noise background.