FM Jammer Suppression in GPS Receivers Exploiting Sparsity and Chirp Signal Approximations

Moeness G. Amin, Yimin D. Zhang, Ben Wang

Peer Reviewed

Abstract:	Anti-jamming capability is critical for GPS receivers operated in challenging environments as GPS reception is vulnerable to jammers. An important class of jammer is frequency modulated (FM) signals whose waveforms exhibit nonstationatity by the virtue of linearly or nonlinearly sweeping the signal bandwidth over time. These FM jammers display clear signatures in the time-frequency (TF) domain. As such, suppression of FM jammers is typically performed by utilizing the joint time-frequency domain for signal representations. The jammer instantaneous frequency (IF) is first estimated through linear or bilinear TF analysis methods, and then this estimate is used to remove the jammer through a variety of filtering and projection techniques. In this paper, we consider an effective method for complex jammer IF signature estimation. Our focus is on the case where the received signals are incomplete, i.e., the received GPS signals, contaminated by FM jammers, do not follow the typical assumption of uniform Nyquist sampling. Rather, some data samples are missing due to, for example, impulsive noise removal, line-of-sight obstruction, and/or multipath fading. The method proposed in this paper is based on sparse TF signature reconstruction for jammer IF estimation. It utilizes the fact that the FM jammer signals have continuous IF signatures that are well approximated by piece-wise chirps. Such approximation calls for using chirp atoms in sparse signal TF representation. It is demonstrated that the use of chirp dictionary is deemed to enhance IF estimation with improved IF signature conti¬nuity compared to the conventional sinusoid dictionary.
Published in:	Proceedings of the 28th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2015) September 14 - 18, 2015 Tampa Convention Center Tampa, Florida
Pages:	3284 - 3288
Cite this article:	Amin, Moeness G., Zhang, Yimin D., Wang, Ben, "FM Jammer Suppression in GPS Receivers Exploiting Sparsity and Chirp Signal Approximations," Proceedings of the 28th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2015), Tampa, Florida, September 2015, pp. 3284-3288.
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