Yasin Yousif Al-Aboosi

arXiv2020

Image denosing in underwater acoustic noise using discrete wavelet transform with different noise level estimation

In many applications, Image de-noising and improvement represent essential processes in presence of colored noise such that in underwater. Power spectral density of the noise is changeable within a definite frequency range, and autocorrelation noise function is does not like delta function. So, noise in underwater is characterized as colored noise. In this paper, a novel image de-noising method is proposed using multi-level noise power estimation in discrete wavelet transform with different basis functions. Peak signal to noise ratio (PSNR) and mean squared error represented performance measures that the results of this study depend on it. The results of various bases of wavelet such as: Daubechies (db), biorthogonal (bior.) and symlet (sym.), show that denoising process that uses in this method produces extra prominent images and improved values of PSNR than other methods.

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arXiv2019

Modeling Of A Shallow Water Acoustic Communication Channel

In these last years, many studies have focalized on the design of reliable underwater acoustic communication systems. However, the ocean acoustic communication channel exhibits strong amplitude and phase fluctuations and the phenomena of diffraction, refraction and reflection. Due to the complexity of the environment, the motions of transducers, sea surface, etc., the underwater acoustic signals exhibit random temporal and spatial frequency fluctuations in both amplitude and phase. Therefore, it is very important to model a so complex channel. Acoustic propagation is characterized by three major factors: attenuation that increases with signal frequency, time-varying multipath propagation, and low speed of sound (1500 m/s). The background noise, although often characterized as Gaussian, is not white, but has a decaying power spectral density. The channel capacity depends on the distance and may be extremely limited. In this paper, we propose a new multipath channel model for shallow underwater acoustic communications. In particular, our model takes into account the effects due to spreading loss, scattering and reflections.

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