A comparative analysis of adaptive notch filtering and wavelet mitigation against jammers interference:

It is well known that, due to the weakness of the received Global Navigation Satellite Systems (GNSS) signals, GNSS receiver operation may be easily and seriously threatened either by the presence of several impairments such as the unintentional interference, generated by other communication systems; or the intentional interference known also as jamming; and spoofing signals which attempt to mislead receiver operation. The term jamming refers to intentional transmission of RF interference with the goal of disrupting one or more of the received GNSS frequency bands, preventing the receivers from operating correctly within a targeted area. This paper provides a comparison between two interference mitigation techniques at the digital signal processing level for jamming signal removal. The traditional adaptive notch filtering scheme, widely discussed in literature, has been compared with a more innovative technique based on the use of the Wavelet Packet Decomposition (WPD). Both techniques are implemented in software and their performance has been assessed via the use of a fully software GNSS receiver. Both techniques are first applied to a set of simulated GNSS jammed scenarios and preliminary results demonstrates that not negligible improvement is achieved at both acquisition and tracking level when the WPD algorithm is employed with respect the application of the classical adaptive notch filtering. In fact, using the adaptive notch filtering the effective range of the jamming can be reduced from approximately 474 meters up to 127 meters while when using the WPD based algorithm, such a range can be further reduced up to approximately 10 meters. These results are also confirmed by successive test campaign where performance comparison of both software implemented techniques is assessed considering synthetic GNSS data interfered at Radio Frequency (RF).