时变单音干扰下GPS系统的性能分析及干扰抑制方法

Performance analysis of GPS and interference cancellation scheme in presence of time-varying single-tone jamming

针对实际系统中干扰源的移动特性,将干扰信道建模为时变瑞利衰落信道,分析了时变单音干扰下多普勒频移对GPS系统性能的影响并推导了误码率公式,提出了一种基于短时傅里叶的自适应时频域干扰抑制算法。该算法首先对接收到的GPS信号进行时频分析,检测出受到干扰的频点,然后设置合理的干扰剔除门限,最后通过自适应二阶IIR格型陷波器将所受干扰的频点剔除。与基于LMS的时域自适应滤波算法进行了对比,实验证明,所提算法对时变单音干扰具有较好的干扰抑制能力。

The interference channel is modeled as a time-varying fading channel as the motivation of the jamming sources in the practical scenario. Focusing on this problem,this paper analyzed the effect of the Doppler shift on the performance and derived the BER expression in the presence of time-varying single-tone jamming on GPS（ global positioning system）,and proposed an adaptive short-time Fourier transform（ STFT）-based jamming mitigation system. Firstly,it made a time-frequency（ TF） analysis of the received GPS signals to detect the contaminated frequency bins,and then set a proper threshold which used to mitigate the jamming signal. Finally,it used a second-order IIR filter with a lattice structure to null the estimated contaminated frequencies. Compared with the adative filtering algorithm based on LMS,simulation results show that the proposed method can perform better than adaptive filtering techniques.