| Combined the fractional Fourier transform (FrFT) theory, a method for detecting the target echo in reverberation is proposed 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 (u domain) for each block. Then the signal is recovered through inverse FrFT. Final output of the system is the energy of the signal. When target echo exits in one block, the output energy is strong. By using this method, we solve the problem of error filter though searching for the peak value in u domain. The result of numerical simulation and lake experimentation show that the method has better detection performance than matched filter¡¯s. |