Research On Detection Methods Of Adaptive Line Enhancer

Under the background of strong radiated noise,weak target detection and extraction has been the focus of underwater acoustic signal processing research.Aiming at this problem,the classical spectrum estimation method and adaptive line enhancer commonly used in signal detection are studied deeply and used widely as the basic methods.And in this paper,the traditional adaptive line enhancer will be changed and combined with multi-stage background balance and principal component analysis to improve the detection performance.Firstly,the existing adaptive line enhancer method will be improved.Use two different time delay adaptive line enhancer structures to enhance the signal,then the two-way outputs do cross power spectrum.Because of the different time coherent characteristics between the signal and noise,the noise will be removed again to raise the signal-noise ratio.Then,this paper explores the effects of the combined processing methods.The principal component analysis is used as the preprocessing part of the adaptive line enhancer.Get the main components of the input signal first in order to remove the noise on a certain degree.And then put the extraction of the main components of the signal to the adaptive structure for further enhancement.This application can effectively remove the momentary interference noise of high energy and wide frequency bandwidth to present a clear LOFAR figure showing signal line spectrum.Multi-stage background balance method plays as a post-processing role in conjunction with adaptive line enhancer.The input signals do the amplitude adjustment in time domain first to reduce the fluctuation of the signal.And the weak signal is enhanced by the way.Then the output signal carry on the spectrum adjustment in frequency domain to weaken the background noise and emphasize the signal line spectrum.It will take out the background noise and retain more signal components at the same time.At the end,by means of calculations and simulations under the conditions of Gaussian colored noise,non-Gaussian noise and actual data of sea experiments,these methods achieve very good detection results.The performance of existing adaptive signal detection method is much improved,so that it can be better used in the environment of strong noise extraction and weak signal detection.And the essay also provides new methods and ideas for the research of underwater acoustic signal processing.