De-noising algorithm for SNR improvement of underwater acoustic signals using CWT based on Fourier Transform

摘要

Underwater wireless communication is a prominent research field owing to its vast range of applications such as underwater sensor networks, remotely operated vehicles (ROVs) and tsunami warning systems. The acoustic signals used in the underwater wireless systems are 105times slower than light which makes it band-limited. Communication under water is affected not only by natural activities but also by shipping noises, all of which degrade the performance of underwater systems. Hence appropriate de-noising algorithms have to be developed to improve the performanceof the band-limited underwater systems. The algorithm described in this paper was developed using linear frequency modulation (FM) waveform as input and using the continuous wavelet transformation (CWT) based on fast Fourier Transform (FFT) method with Morlet wavelet. The proposed algorithmprovides an SNR improvement of around 12 dB when compared with the algorithm developed using the chirp signal as input and using Morlet wavelet with wavelet packet decomposition (WPD) technique.