The paper presents a detailed scheme on the reliable recognition of the ultrasonic echo-signal in high noise background. Based on the scheme, a detailed discussion of the application of the traditional digital processing methods in this field is proposed in this paper. Based on the traditional methods of wavelet analysis, some of novel algorithms are also proposed in the paper and have been programmed using Matlab. This paper also analyzed the problems that lie in the application of wavelet analysis method in the filtering of the signal with narrow spectrum. The causes of this problem are proposed and a new method of constructing the daughter wavelets is given to apply the wavelet analysis in the filtering of the signal with narrow spectrum successfully.
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