In-Band Cancellation of Jamming for Robust GPS Navigation

Rick Vosburgh, Charley Wilson, Vrinda Haridasan

Abstract:	The present paper describes Continuous Adaptive In-band Nulling (CAIN) for signal agnostic in-band cancellation and blocking of interference. CAIN comprises an ultrawideband tunable RF filter for cancellation of narrowband and wideband jamming at GPS, and other frequencies from White Space to Wi-Fi. CAIN employs two closely spaced (?/4) antennas or antenna elements connected to a low size, weight, power and cost (SWAP-C) circuit assembled of COTS components for single-pass feedforward anti-jamming using a deterministic calculation of phase shift to align the jamming content of one antenna signal anti-phase with respect to jamming content of the second antenna signal, steering a sharp null precisely (<0.1 degree) at a jammer, cancelling it by >>30 dB. Modeling and field test data are presented to characterize CAIN at GPS and other UHF frequencies. Results are also presented on the use of an antenna arrangement in which a nulling field is induced around a GPS antenna to block jamming rather than removing it after the fact. Cancellation and blocking can be used to additive effect against a single jammer or to defeat two independent jammers. Initial modeling of passive linear phase bandpass filters is presented as means of enhancing localization by precision GPS receivers. CAIN, as an effective defense against jamming, is also expected to deter what would be futile jamming attack, including against GPS-dependent infrastructure.
Published in:	Proceedings of the 2013 International Technical Meeting of The Institute of Navigation January 29 - 27, 2013 Catamaran Resort Hotel San Diego, California
Pages:	856 - 863
Cite this article:	Vosburgh, Rick, Wilson, Charley, Haridasan, Vrinda, "In-Band Cancellation of Jamming for Robust GPS Navigation," Proceedings of the 2013 International Technical Meeting of The Institute of Navigation, San Diego, California, January 2013, pp. 856-863.
Full Paper:	ION Members/Non-Members: 1 Download Credit Sign In