Research On Noise Cancellation Under High Noise Condition

Noise interference with voice communications, resulting in the deterioration of voice quality. Especially under the high noise condition, voice signals was even completely overwhelmed by background noise and almost impossible to identify. Voice communications can not be achieved. It has a significant impact on industrial production, daily life and military operations, also makes huge economic losses to the individuals, factories and even the nation. Therefore, under the high noise condition, how can we suppress and eliminate the noise effectively has become a hot research issue.This paper is based on the study of voice processing in VHF communications system,which is one part of the project of the vessel traffic management systems of between Zhicheng Bridge Station of Yichang and Badong station The purpose of this paper is to denoise in voice communications under high noise condition.After the analysis and comparison of existing denoiseing methods, feasibility of adaptive noise cancellation was selected. Then, the finite impulse response (FIR) horizontal filter structure and recursive least squares (RLS) algorithm were chosen to construct the system model after the analysis and comparison of the structure and algorithm.Adaptive filtering algorithm was the main contents of this paper. Based on in-depth analysis of the standard recursive least squares (RLS) algorithm, the improved scheme was proposed for its inherent weaknesses.Three improved algorithms were introduced which has been successfully used in adaptive equalization and adaptive estimation. Then, the standard recursive least squares (RLS) algorithm and the improved algorithms were applied to adaptive noise cancellation system.The above four algorithms denoised the voice signal by MATLAB simulations, which was interferenced by noise. And the experimental results were analyzed and summarized.A new least-squares algorithm based on the Kalman filter was proposed by Kwang-Seop Eom and the other people. The algorithm(ISPRLS algorithm) not only has a fast tracking capability, but also was immunised against measurement noise. Under the high noise condition, it also can achieve excellent denoising effect.The effectiveness of the algorithm were confirmed by computer simulations.