CHEN Wenjian  SUN Hui  ZHU Jianjun  ZHU Guangping  ZHANG Minghui

(National Laboratory of Underwater Acoustic Technology, Harbin Engineering University Harbin 150001)

Received Mar. 2, 2009

Revised May 15, 2009

Abstract A method for detecting the target echo in reverberation was proposed based on fractional Fourier transform theory when the transmitted signal is linear frequency modulation signal. The slow time-varying envelope of reverberation is computed to process reverberation to be stationary. The stationary reverberation is cut into blocks using a sliding window. A narrow-band filter is applied in FrFT domain for each block and the signal is recovered through inverse FrFT. Output of the system is the energy of the recovered signal. When the target echo is included in one of the blocks, the reverberation noise is reduced, and the output is the energy of the target echo. All the simulation and lake experiment results show that the detection performance of the present method is better than that of the matched filter.

PACS numbers: 43.30,43.60