卫星导航接收机中积分清零器的性能分析

Performance of integrate and dump filters in GNSS receivers

为了使跟踪环路得到最高的输入信噪比,卫星导航接收机在时延估计时应使用匹配滤波器。但出于节省硬件资源的考虑,卫星导航接收机通常采用积分清零器完成相关运算。然而积分清零器相对于匹配滤波器存在性能损耗,对此目前尚无量化的结论。本文推导出积分清零器性能损耗的解析表达式,并使用Monte Carlo仿真的方法验证结论的正确性。理论和仿真结果表明当采样率为2倍的前端带宽时,积分清零器相比匹配滤波存在约0.44dB的损耗,当采样率提高到4倍信号带宽时,积分清零器的性能损耗几乎可以忽略。该结论对卫星导航接收机的设计具有重要的意义。

In global navigation satellite system （GNSS） receivers, matched filters should be applied in time delay estimation to maximize signalto-noise ratio of tracking loops. Integrate and dump filters are often used as a simplification to reduce hardware cost; however, there is no quantitative conclusion about its performance degradation yet. To deal with this issue, analytical expression of performance degradation is derived, and Monte Carlo simulations are given to support the analysis. Theoretical and simulated results show that the performance degradation is about 0. 44rib if sampling frequency is twice of signal bandwidth, and it can be neglected if sampling frequency is increased to four times of signal bandwidth.