CAJ | 학술논문

针对小波阈值去噪传统方法所使用的阈值函数存在不连续或估计的小波系数存在偏差导致去噪效果不理想的问题，提出了双重指数型阈值函数。该阈值函数呈双重指数形式，不是分段函数，含有一个调控参数控制估计的小波系数向分解的小波系数或0逼近的速度，以阈值和分解的小波系数的比值是否大于1判定估计的小波系数的逼近方向。仿真结果表明在对多普勒回波的去噪过程中，使用双重指数型阈值函数的去噪结果优于使用传统阈值函数的去噪结果。
침대소파역치거조전통방법소사용적역치함수존재불련속혹고계적소파계수존재편차도치거조효과불이상적문제，제출료쌍중지수형역치함수。해역치함수정쌍중지수형식，불시분단함수，함유일개조공삼수공제고계적소파계수향분해적소파계수혹0핍근적속도，이역치화분해적소파계수적비치시부대우1판정고계적소파계수적핍근방향。방진결과표명재대다보륵회파적거조과정중，사용쌍중지수형역치함수적거조결과우우사용전통역치함수적거조결과。
For the threshold function used by the traditional method of wavelet threshold denoising presence not continuous or the estimated wavelet coefficients had deviations cause the denoising effect undesirable,a double exponential threshold function was put forward.The threshold function was a double exponential form but a piecewise function,containing a control parameter which controled the approximation rate of the estimate wave-let coefficients to the decomposition wavelet coefficients or 0,determined the estimated wavelet coefficients ap-proach direction with size of the relationship between 1 and the ratio of the threshold and the decomposition wavelet coefficients.Simulation results showed that during the process of de-noising on the Doppler echo,the results of double exponential function threshold denoising was better than using traditional threshold function denoising .