Review on Quadratic Phase Transformation for Underwater Imaging Sonar Based on the FFT

In deep sea exploration and ocean engineering, underwater imaging sonar has been widely used because of its ability of remote sensing navigation and independent operation. Aiming at the problem that it is easy to produce complex imaging and difficult analysis in polluted water or harsh environment, this paper proposes a quadratic phase transformation method of underwater sonar image based on FFT. In this paper, firstly, the frequency spectrum of each sonar signal is analyzed by fast Fourier transform technology, and the relationship between the corresponding frequency characteristic value and the quadratic phase transformation is determined by studying the correlation between the frequency domain characteristics of the original echo signal and the target characteristics. Then, on this basis, the quadratic phase transformation method is introduced to adjust the reflection characteristics of the signal, so as to realize the fine processing of underwater target recognition and imaging. The experimental results show that this method can effectively eliminate the phase distortion of signals, thus improving the quality of sonar imaging and making underwater imaging clearer, which has important guiding significance for the study of complex underwater environment and deep-sea exploration.