Research Online: Narrowband interference mitigation, spoofing interference classification

Spectrum of the Adaptive Notch Filter output signal for various interference levels Photo: Adaptive Notch Filter

Limits of narrowband interference mitigation using adaptive notch filters

By J. Wendel, Frank M. Schubert, Airbus DS GmbH, and A. Rügamer and S. Taschke, Fraunhofer IIS.
Presented at ION GNSS+, September 2016.

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.

Spoofing, jamming and multipath interference classification using a maximum-likelihood multi-tap multipath estimator

By Jason N. Gross, West Virginia University and Todd E. Humphreys, University of Texas at Austin.
Presented at ION ITM, January 2017.

This paper experimentally evaluates the application of existing multipath mitigation technology in conjunction with in-band power monitoring for the purpose of GNSS interference classification. Interference detection and classification metrics derived from the output of a multiple-correlation tap, maximum-likelihood multipath estimator are jointly used for the alarming the presence of GNSS spoofing, jamming or multipath. This approach is evaluated against a dozen sets of deep urban multipath recordings, several recordings of wideband jammers at several different power levels, and clean static data recordings. Two detection approaches are proposed, and one is shown to be better at discriminating between spoofing and jamming attacks.