Limits of narrowband interference mitigation using adaptive notch filters

Interference and jamming are of growing concern for the GNSS community. The robustness of a GNSS receiver against interferences can be increased significantly by using an adaptive notch filter, which estimates the instantaneous frequency of the interfering signal and suppresses it. In this paper, the foundations of adaptive notch filtering are described. Then, experiments are performed with an arbitrary waveform generator for jamming signal generation combined with a space segment simulator for GNSS signal generation. The resulting signals are recorded and post-processed in a software GNSS receiver, which implements an adaptive notch filter for interference mitigation. This setup is used to demonstrate mechanisms that limit the interference mitigation capabilities of adaptive notch filters.