Research On Feature Extraction Methods Of Passive Targets

Recognition technique on underwater targets is an important research in the underwater acoustic signal processing field, but also one of the difficulties in the filed. Feature extraction is the key link of the targets recognition, on account of the sea environment complexity and the underwater acoustic channel particularity, it's difficult problem to extract a kind of target essence feature and underwater distant detection effective feature.Firstly, the paper introduces the conventional method of extracting modulation feature of passive target, and research an improved DEMON analysis method based on wavelet transform and high distinguishable ZFFT. By Compared to conventional methods , the method take full advantage of the information of the signal in all frequency band, improving the demodulation quality.Secondly, after having got the information of the DEMON line-spectrum, the paper estimates the frequency features of the target by using difference frequency and double frequency method, and compares the two methods.Lastly, in order to solve the problem of frequency estimate precision in low SNR, the paper combine fractal theory and wavelet, inspired by the fractal idea, extracting the new feature- wavelet mufti-resolution energy fractal features to detect passive target. The paper introduce detailed the basic mind and principle , and do some simulation research . The results of simulation experiment proves that it is suitable for the new feature parameter; which provides new feature extraction method and new feature parameter for the detection of passive targets.