A Novel Algorithm for Adaptive Notch Filter to Detect and Mitigate the CWI for GNSS Receivers

The continuous wave interference (CWI) and the pulsed CWI have been shown to have severe impacts on the quality of the received GNSS signal. This paper presents a novel algorithm for adaptive notch filter (ANF) based on direct form structure, which is constructed of the second-order infinite impulse response (IIR) notch filter with constrained poles and zeros in detection and mitigation of CWI for Global Navigation Satellite System (GNSS) receivers. The novel algorithm for ANF can estimate each CWI frequency and computer the power of each CWI in frequency domain, then give the appropriate value of the other parameter for ANF by looking up the Mapping Table which shows the one-to-one relationship between the power of CWI and the depth of ANF. Finally, it constructs the ANF when there is a CWI in time domain. The effective carrier-to-noise power ratio (C/N
₀
) is introduced to reflect the effect of interference on characteristics at the input of the GNSS receivers. In order to assess the performance of the novel algorithm to detect and mitigate the CWI on GPS L1 signals, positioning accuracy which reflects the final capability of most GNSS receivers is proposed. A group of experiments has been carried out to prove the performance of the novel algorithm. From the results of experiments, the novel algorithm for ANF can detect the CWI in frequency domain, and mitigate the CWI in time domain.