GNSS Interference Localisation Method Employing Inverse Diffraction Integration with Parabolic Wave Equation Propagation

Troy A. Spencer, Rodney A. Walker and Richard Hawkes

Abstract:	While GPS is a relatively mature technology, the susceptibility of the standard positioning service (SPS) to radio frequency interference (RFI) is substantial. Various reports have been presented in relation to GPS susceptibility. The Volpe report provided to the U.S. Department of Transport in 2001 [1], recognised and highlighted the vulnerability of GPS to RFI. The “GPS Risk Assessment Study” report provided by the John Hopkins University Applied Physics Laboratory in 1999 [2] did not consider the risk of GPS to intentional interference to be significant, but it concurred with the Volpe report in recommending that methods should be developed to monitor, report and locate interference sources for applications where loss of GPS is not tolerable. With NAVSTAR-GPS becoming an integral part of developed society, high significance must be placed on research that can improve the capabilities of GPS RFI localisation. In response to the Volpe report recommendation for development of interference localisation methods, a novel technique referred to as the Inverse Diffraction Parabolic Equation Localisation System (IDPELS) has been developed. This localisation technique involves the integration of inverse diffraction with the Parabolic Wave Equation Model (PEM). PEM is an electromagnetic propagation modelling tool that has been extensively used for many applications where information concerning radar coverage is required. The application of PEM requires the terrain profile to be apriori known. In an urban environment, the possibly of non-line-of-sight (NLOS) paths existing is highly realistic. The motivation for conducting this research was to determine how useful the IDPELS technique would be for scenarios where only NLOS signal paths, between the jamming source and detecting antenna array existed. The hypothesis to be tested concerned whether an improved localisation estimate could be made with the use of an inverse propagation model and detailed knowledge of the terrain. Simulation results of IDPELS have indicated that in a free-space environment, it is a technique that is capable and accurate in performing localisation of multiple interference sources. With the increasing reliance being placed on GPS, IDPELS is a technique that should be considered when current strategies are not ensuring the availability of GPS.
Published in:	Proceedings of the 17th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2004) September 21 - 24, 2004 Long Beach Convention Center Long Beach, CA
Pages:	87 - 98
Cite this article:	Spencer, Troy A., Walker, Rodney A., Hawkes, Richard, "GNSS Interference Localisation Method Employing Inverse Diffraction Integration with Parabolic Wave Equation Propagation," Proceedings of the 17th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2004), Long Beach, CA, September 2004, pp. 87-98.
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