基于小波分析的侧扫声呐信号非线性增强算法

Nonlinear Enhancement Algorithm of Side Scan Sonar Signal Based on Wavelet Analysis

摘要:

侧扫声呐回波信号是形成侧扫声呐图像的基础，是侧扫声呐系统对水下目标的最直接观测量， 将一维小波变换与非线性增强方法相结合，提出了一种基于小波变换的侧扫声呐回波信号非线性增强算法， 用以改善侧扫声呐图像对比度低、噪声强度大的问题。首先利用改进的 Bayes 阈值对侧扫声呐 ping 信号进行一维小波分解，提取信号特征信息；然后利用 2 种不同的非线性函数对高、低频小波系数进行处理；最后利用小波反变换重构信号，形成增强后的侧扫声呐图像。实测数据验证结果表明：利用该算法对侧扫声呐 ping 信号进行处理，实现了侧扫声呐图像对比度的增强和对噪声的抑制，可以获取较好的图像视觉效果。

Abstract:

The sidescan sonar echo signal is the foundation for sidescan sonar image formation，and it is the most directly observed quantity of the underwater target by the side scan sonar. Combining one-dimensional wavelet transform with nonlinear enhancement method，this paper proposes a nonlinear enhancement algorithm of side scan sonar signal based on wavelet analysis to improve the problems of low contrast and strong noise intensity of the side scan sonar image. Firstly，the one-dimensional wavelet decomposition is performed on the ping signal of side scan sonar with improved BayesShrink to obtain signal characteristic information. Then two different nonlinear functions are used to process the high frequency and low frequency coefficients. Finally，the inverse wavelet transform is used to reconstruct the signal to form an enhanced image. The verification result of measured data shows that the method proposed by this paper can realize the enhancement of image contrast and the noise suppression，and can obtain a better visual effect of image.