高频雷达中提取海洋回波信号的新方法

雷达信号经过海面反射时,由于电离层的作用和外部的干扰,必然会有一些噪声夹杂在海洋回波中。噪声是一些无规则的频谱,对分析有用信号是极其不利的,严重时甚至淹没有用的信号。将噪声中的信号提取出来成了一个很关键的问题。基于海洋回波信号是1/f类分形信号的特性,利用不同尺度下小波系数方差来估计噪声方差及分形信号参数,进而从白噪声背景下估计出海洋回波信号。实验结果表明:用新方法处理过的海洋回波的多普勒谱的信噪比提高了10-15 dB。

New method to pick up sea echo signal in HF radars

owing to the interferences of the ionosphere and other factors,some noises must be mixed with the radio signals which are reflected by the sea surface.The noises' spectrum is random,so it is very disadvantageous to analyse the useful sea echo signal.Therefore,it is a key subject to pick up the signals from the noises.However,in respect that the sea echo signal is 1/f fractal signal,and based on the variance of the wavelet coefficients of fractal signal at different levels,a new method of estimating the variance of noise and parameters of sea echo signal is proposed,then the fractal sea echo signal can be estimated from the white noise.The results show that the SNR of the DOPPLER spectrum of sea echo signal is promoted 10-15 dB by this effective new method.