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Jam-Resistant Global Positioning System/Inertial Navigation System (GPS/INS) Deeply-Coupled Navigation System


OBJECTIVE: Design and develop high performance and jam-resistant Global Positioning System/Inertial Navigation System (GPS/INS) navigation technologies in support of the Navy Warfighter. DESCRIPTION: GPS vulnerability to radio frequency (RF) interference is well known. An inexpensive one-watt noise jammer can deny GPS availability at distances of many miles for some receiver types. The integration of GPS with INS offers significant anti-jam (AJ) and other navigation performance benefits. The INS can aid the GPS signal tracking loops, allowing reduction in bandwidth and hence provide more immunity to jamming. The INS error models may be calibrated by GPS when available, and the INS may be used as a flywheel navigation capability when GPS is completely denied by jamming [1]. Many loosely and tightly-coupled GPS/INS navigation systems have been deployed in existing air vehicle and other types of systems, e.g. the Embedded GPS/INS (EGI) [2]. More recently deeply-coupled GPS/INS architectures have been shown to offer significant enhancements to AJ and other measures of performance beyond traditional GPS/INS loose and tight-coupling configurations. Two examples of deeply-coupled GPS/INS designs are described in references [3] and [4]. Standardized requirements, form factors and interfaces suitable for replacement and upgrade of currently deployed military navigation systems in existing air, sea and ground systems, and for integration in new military systems are desired. The GPS/INS technologies developed under this SBIR will need to surpass the existing technologies by maintaining the Positioning Navigation and Timing (PNT) service and achieving good accuracy at jammer-to-signal power ratio J/S levels of at least 75 dB using Microelectromechanical systems (MEMS) Inertial Measurement Unit (IMU) quality characteristics as indicated in reference [4]. Fast, jamming and spoofing-resistant capabilities are desired for the GPS signal acquisition and reacquisition states. Size, weight and power (SWAP) should be suitable for precision guided munitions (PGMs) tactical weapon systems ranging from 10-inch to 30-mm diameters, and unmanned air systems (UAS) ranging from Group 1 to Group 4 categories. [5] The GPS/INS technologies need to meet military GPS receiver Selective Availability Anti-Spoofing Module (SAASM) security, reliability, environmental, and other requirements for operational use. Objectives include anti-spoof protection and synergistic operation with other GPS anti-jam technologies. Offerors should consider working with platform prime contractors, navigation system prime contractors and others, as appropriate. PHASE I: Design and demonstrate proof-of-concept for GPS/INS deeply-coupled configurations. Analyze performance and suitability of designs to support successful mission operations using representative air and other vehicle mission scenarios. PHASE II: Further develop the designs into mature test beds and prototype systems and demonstrate performance. PHASE III: Finalize system that meets the operational requirements. Integrate, test and transition the resulting technology as appropriate. PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: This technology may also be used for navigation on commercial air, sea and ground vehicle systems, e.g. civilian manned and unmanned air vehicles. Because of the proliferation of low-cost GPS jammers, the FAA is becoming more concerned about the loss of GPS signals due to RF interference, such as recently occurred in the Newark airport area. In this case, GPS/INS deeply-coupled architectures provide significant AJ protection to allow continuation of the navigation function at higher RF interference levels, e.g. to maintain continuity of the navigation function during the critical approach and landing phase. REFERENCES: 1. Parkinson, B., Spilker J., Axelrad, P. & Enge, P. (1996). Global Positioning Systems, Theory and Applications, Volume II. 2. Embedded GPS/INS (EGI). 3. Gustafson, D., Dowdle, J. & Flueckiger, K. (2000). A High Anti-Jam GPS-Based Navigator. Proc. ION National Tech. Meeting. & idno=60 4. Ohlmeyer, E. (2006). Analysis of an Ultra-Tightly Coupled GPS/INS System in Jamming IEEE Position Location and Navigation Symposium (PLANS). & tag=1 5. Weatherington, D. (2010). Unmanned Aircraft Systems OUSD(AT & L)/PSA.
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