改进的超低频广义旁瓣噪声抵消算法

为了有效地改善超低频频段的通信质量,在广义旁瓣抵消算法的基础上,提出了一种改进的广义旁瓣噪声抵消算法。首先,该算法将主通道中的延时求和用线性滤波算法代替,有利于进一步提高非相干噪声的抑制能力;其次,鉴于各通道信号强度存在差异,采用优化后的阻塞矩阵代替原来的简单相减阻塞矩阵,有利于减少期望信号的残留,从而提高算法的性能;最后,采用线性滤波代替原来的自适应算法,可以在实现噪声抵消的同时不降低主天线的灵敏度,且提高算法的运算速度。为了验证所提算法的有效性,在实验室环境下搭建了实验平台,设计了多组对照实验。实验结果表明,这种模拟电路可有效地抑制工频及其谐波干扰。改进后的广义旁瓣抵消算法相比于原算法,在信噪比和噪声底限的改善上有较大的成效。

Improved generalized sidelobe cancellation algorithm in ELF communication

In order to improve the communication quality in extremely-low-frequency(ELF) communication, based on the generalized sidelobe cancellation(GSC) method, an improved GSC method is proposed and constructed. First, the delay summation in the main channel is replaced by the linear filtering algorithm, which is beneficial to further improving the suppression ability of incoherent noise. Second, by considering the difference in signal energy among channels, using the optimized blocking matrix can reduce the amplitude of the desired signal and improve the performance, comparing to the original blocking matrix obtained by simple subtraction among the main channels. Finally, the method using linear filtering instead of the original adaptive algorithm can achieve noise cancellation without reducing the sensitivity of the main antenna and improve the algorithm’s operating speed. In order to verify the effectiveness of the proposed algorithm, an experimental platform is set up in laboratory environment and a series of control experiments are designed. Experimental results show that the designed analog circuits can suppress 50 Hz and its harmonic components and that the improved GSC algorithm is better than the original algorithm in terms of improvement of the signal-to-noise ratio(SNR) and the noise floor.