关键词: 非高斯噪声, 小波变换, 阈值函数, 软阈值, 硬阈值, 高阶幂函数

Abstract: A new threshold function under non-Gaussian noise background was presented to overcome the limitations of wavelet threshold algorithm under the Gaussian noise background. The shortcomings of conventional function, such as discontinuity of hard threshold function and the invariable dispersion of soft threshold function, can be solved. The new function which employed high order power function was put forward based on Garrote threshold. First, the signal with a class of non-Gaussian noise was decomposed by wavelet. Secondly, each high frequency wavelet coefficient was quantified based on new threshold function. Thirdly, signal was reconstructed by the low frequency coefficients of wavelet decomposition and quantified high frequency coefficients. The simulation results under non-Gaussian noise background indicate that the new threshold function gets higher Signal-to-Noise Ratio (SNR) gains and lower minimum Mean Square Error (MSE) compared to the soft and hard threshold, two types of improved threshold and Garrote threshold.

Key words: non-Gaussian noise, wavelet transform, threshold function, soft threshold, hard threshold, high order power function