基于改进自适应滤波的广播电台信号非平稳干扰抑制研究

面对广播电台信号的非平稳干扰时,受到回波信号的时变性影响,导致干扰抑制效果不佳。为了解决该问题,提出了基于改进自适应滤波的广播电台信号非平稳干扰抑制方法。根据广播电台信号产生原理,计算脉冲重复周期内的广播回波信号,以此构建广播电台非平稳干扰信号。使用改进自适应滤波方法设计自适应信号分离器,从混合信号中分离出目标信号,有效提取有用信息。通过改进自适应滤波的差拍处理,分析移频量为0和不为0的2种情况,构建由差拍信号输入到干扰输出的改进自适应滤波响应函数,采用改进自适应滤波算法输出干扰抑制信号,计算带宽大小自适应步长。通过控制步长,抑制目标回波对广播电台信号的干扰。由实验结果可知,使用该方法抑制干扰信号时,当频率为3Hz时,频谱幅度值达到最大,为0.2d B,其余频率下的频谱幅度最大值为0.005d B,只与原始频谱幅度存在最大为0.005d B的误差,具有良好干扰抑制效果。

When facing non-stationary interference from radio signals, the time-varying effect of echo signals leads to poor interference suppression. To address this issue, a non-stationary interference suppression method for radio signals based on improved adaptive filtering is proposed. According to the principle of signal generation in radio stations, calculate the broadcast echo signal within the pulse repetition period to construct non-stationary interference signals for radio stations. Design an adaptive signal separator using an improved adaptive filtering method to separate target signals from mixed signals and effectively extract useful information. By improving the beat processing of adaptive filtering, analyzing two cases of frequency shift of 0 and non-0, constructing an improved adaptive filtering response function from the beat signal input to the interference output, using the improved adaptive filtering algorithm to output the interference suppression signal, and calculating the bandwidth size to adapt the step size. By controlling the step size, the interference of target echoes on radio signals is suppressed. From the experimental results, it can be seen that when using this method to suppress interference signals, when the frequency is 3Hz, the spectrum amplitude value reaches its maximum of 0.2dB, and the maximum spectrum amplitude value at other frequencies is 0.005dB. There is only a maximum error of 0.005dB compared to the original spectrum amplitude, which has a good interference suppression effect.