基于最佳一致逼近法的逆海洋滤波器设计

Research on Ocean-compensation Filter Based on Best Uniform Approximation Method

针对海水低通特性会使水下超低频段大气噪声波形畸变,使接收超低频信号时信噪比变差的问题,研究了海水在超低频段的幅频特性,仿真了在不同深度上海水对超低频大气噪声的影响,并采用最佳一致逼近法设计了逆海洋滤波器,对畸变的大气噪声波形进行频率补偿。当采样率fs=1kHz时,在30m^200m深度上最大采用9阶IIR滤波器,可以使逆海洋滤波器的幅频特性与理论值的最大偏差小于0.5dB,能够很好的还原超低频大气噪声尖峰的锐利程度,提高了接收信号的信噪比。

The low‐pass characteristic of the ocean in ELF band will result in distortion of the atmospheric noise and worse signal to noise of the receiver .To address this problem ,magnitude‐frequency characteristic of the ocean in ELF band were researched .Influence on the atmospheric noise in different depth of the ocean was simulated .And ocean‐compensation filter was designed using best uniform approximation method to compensate the distorted atmospheric noise .With the sam‐pling frequency f s = 1kHz ,at 30m ~ 200m depth ,9th‐order IIR filter was used to design ocean‐compensation filter .The maximal error of the magnitude‐frequency characteristic of the filter is less than 0 .5dB compared with the theoretical .With the filter ,the sharpness of the ELF atmospheric noise spikes were restored and the SNR of the receiver was improved .