Wavelet Based Adaptive Notch Filtering To Mitigate Cots Ppds

Privacy protection devices (PPDs) are cheap and freely available global navigation satellite system (GNSS) jammers which interfere with GNSS receivers. This causes major disruption, and therefore these interferences should be mitigated by receivers. Adaptive notch filtering (ANF) is an effective interference mitigation method against PPDs, as these interferences tend to transmit chirp-like signals. However, ANF requires a processing rate that exceeds the data rate of the signal for real-time applications. A wavelet based adaptive notch filter (WANF) is proposed as a method to parallelize the processing. This method uses a discrete wavelet transform (DWT) to separate the signal into multiple channels, where ANF can be done at a reduced processing rate, before the signal is reconstructed again. This mitigation method is tested against real PPDs signals, as well as being compared to other popular mitigation methods. Results show that the WANF has superior performance to ANF, and is considered an effective method against PPDs. Further, the WANF is more robust against to a non-flat spectrum but it does cause inter-channel mixing in the presence of strong interferences. The WANF is an improvement to the performance and robustness of ANF, but requires more processing resources, however, it can be parallelized, making it an enabler of ANF especially for high data rate reception channels.