Detect, Locate, and Mitigate GPS Threats

TECHNOLOGY AREA(S): Sensors OBJECTIVE: The objective of this topic is to develop an innovative approach to detecting, locating, and potentially mitigating RF sources of GPS jamming and spoofing. DESCRIPTION: Novel processing techniques have increasingly begun utilizing the geometric RF-diversity of hostile transmitters, i.e., jammers, to mitigate unfriendly signal injection. These techniques typically "form" weighted divergent measurements, from RF samples, based on energy, directional delay and Doppler. In addition to mitigation of these signals, some algorithms have been developed to determine direction of arrival of these hostile RF signals (primarily jammers). For example, MUltiple SIgnal Classification (MUSIC) algorithms use controllable reception pattern antenna (CRPA) derived covariance matrices to determine angle-of-arrival for jamming signals (or signals with higher-than-expected energy). This SBIR aims at the development of novel techniques, which use existing antenna configurations or minor changes to the vehicle's RF front-end, to determine direction-of-arrival of malicious interference sources (i.e., trackable spoof signals) on a missile platform (potentially extendable to other platforms). Direction-of-arrival determination of such interference may rely on the geometric diversity of multiple antennas, multipath assumptions or other RF characteristics that highlight unique transmitter-related RF characteristics. For example, trackable interference, aka spoofers, likely generate the entire GPS-like constellation and transmit from a common point; thus, these signals generate exogenous constellation-wide delay (i.e., in a bend-pipe versus line-of-sight RF transmission). Other defining characteristics of a malicious interference may include increased energy (i.e., jammers), clock drift/offset coloring, inter-satellite interference, etc. In the proposed solution, SBIR respondents are encouraged to use generally realizable, or available, hardware and assets on missile platforms to achieve an on-board mitigation routine for interference signals. The available hardware may include on-board CSAC (chip scale atomic clocks), a FRPA antenna and, potentially, one multiple-element CRPA antenna+module (with available covariance estimation). Software approaches are encouraged, but minor hardware upgrades may be considered. PHASE I: Initial research and first-order simulated results. Work performed under Phase I is expected to develop and determine the feasibility of several novel techniques and to develop a preliminary design for a selected approach. The technique development and evaluation is expected to provide a reasonable literature search and an initial evaluation of at least two options in software (The software may assume static or dynamic motion relative to the interference source.). Each technique should also incorporate hardware/software requirements. The Phase I deliverable will be a final report detailing all methods studied plus evidence of their feasibility on an aerial platform. The final report will also include an initial prototype design to be implemented in Phase II. PHASE II: Work performed in Phase II is expected to mature the Phase I design, implement selected approaches, and develop a prototype system to detect, locate, and potentially mitigate RF sources of GPS jamming and spoofing. Use of GPS simulators and laboratory signal generators to simulate electronic interference will be used in this phase. Phase II deliverables will be a prototype system, as well as a final report describing the prototype design and implemented approaches. PHASE III: In Phase III, the prototype system will be matured and finalized. A technology transition plan will be developed for consideration by US Army program managers. Commercialization applications include other DoD users operating in contested GPS environments, as well as commercial sectors such as aerial transportation, and potentially truck, train, and naval transportation. REFERENCES: 1: Chen, Yu-Hsuan, et al., Design and Implementation of Real-Time Software Radio for Anti-Interference GPS/WAAS Sensors, Sensors journal, ISSN 1424-82202: (Removed on 5/16/17.)3: (Removed on 5/16/17.)4: (Removed on 5/16/17.)5: Tao, Huiqi, Li, Hong, Zhang, Weinan, Lu, Mingquan, "A Recursive Receiver Autonomous Integrity Monitoring (Recursive-RAIM) Technique for GNSS Anti-Spoofing," Proceedings of the 2015 International Technical Meeting of The Institute of Navigation, Dana Point, California, January 2015, pp. 738-744. (Updated on 5/16/17.)6: (Removed on 5/16/17.)7: Timothy Pitt, Greg Reynolds, US Army, AMRDEC; Will Barnwell, US Army, PM UAS; Laura McCrain and Jonathan Jones, NTA, "Test and Evaluation of Mitigating Technologies for Unmanned Aircraft Systems in GPS Degraded and Denied Environments", ION PACIFIC PNT Conference, May 2017. (Added on 5/16/17; uploaded in SITIS on 5/16/17.)8: Starling, J. and Bevly, D. M. "Error Analysis of Carrier Phase Positioning Using Controlled Reception Pattern Array Antennas," Proceedings of the Institute of Navigation International Technical Meeting, Monterey, California, January 2017. (Added on 5/16/17.)9: Powell, R., Starling, J., Bevly, D. M., "A Multiple-Antenna Software GPS Signal Simulator for Rapid Testing of Interference Mitigation Techniques," Proceedings of the 2017 International Technical Meeting of The Institute of Navigation, Monterey, California, January 2017. (Added on 5/16/17.) KEYWORDS: RF, GPS, GPS Threat