With the fast growing diffusion of real-time high-accuracy applications based on the global navigation satellite system (GNSS), the robustness of GNSS receiver performance has become a compelling requirement. Disruptive effects can be induced to signal processing stages of GNSS receivers due to the disturbances from radio frequency interference (RFI), even leading to a complete outage of the positioning and timing service. A typical RFI threat to GNSS signals is represented by portable jammers, which transmit swept-frequency (chirp) signals in order to span the overall GNSS bandwidth. The implementation in the receivers of adaptive notch filters (ANFs) for chirp cancellation has been extensively investigated and proved to be an efficient countermeasure. However, the performance of the ANF is strongly dependent on its configuration setup. Inappropriate parameter settings of the ANF for interference removal may induce severe distortion to the correlation process. In addition, an effective mitigation will still introduce a vestigial signal distortion contributed by the residual unmitigated chirp and the ANF operation itself, being not negligible for high-accuracy solutions. This article addresses the detailed analysis for assessing the effects of interference mitigation by notch filtering. A bias compensation strategy is proposed, wherein for each pseudorandom noise, the biases due to parameter settings of the notch filter are estimated and compensated. The impact of using the ANF operation on chirp signals at the acquisition and tracking stages of GNSS receivers is analyzed. On the basis of the three proposed metrics, the effects can be quantitatively estimated to depict a complete picture of the most influential parameters of the chirp and the ANF configurations, as well as the optimal achievable performance at the acquisition and tracking stages.

中文翻译：

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用于去除干扰的自适应陷波滤波器对 GNSS 接收器信号处理阶段影响的评估

随着基于全球导航卫星系统 (GNSS) 的实时高精度应用的快速普及，GNSS 接收器性能的稳健性已成为迫切要求。由于射频干扰 (RFI) 的干扰，可能会对 GNSS 接收器的信号处理阶段产生破坏性影响，甚至导致定位和授时服务完全中断。对 GNSS 信号的典型 RFI 威胁由便携式干扰机表示，它们传输扫频 (chirp) 信号以跨越整个 GNSS 带宽。用于线性调频消除的自适应陷波滤波器 (ANF) 在接收器中的实现已被广泛研究并证明是一种有效的对策。但是，ANF 的性能在很大程度上取决于其配置设置。用于干扰去除的 ANF 参数设置不当可能会导致相关过程严重失真。此外，有效的缓解仍然会引入残余未缓解的线性调频和 ANF 操作本身造成的残留信号失真，对于高精度解决方案来说是不可忽略的。本文详细分析了通过陷波滤波评估干扰减轻的效果。提出了一种偏差补偿策略，其中对于每个伪随机噪声，估计和补偿由于陷波滤波器的参数设置引起的偏差。分析了在 GNSS 接收机的捕获和跟踪阶段使用 ANF 操作对啁啾信号的影响。在提出的三个指标的基础上，