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Indoor GPS Satellite Constellation Antenna Array




OBJECTIVE: The design, development and fabrication of a realistic indoor GPS constellation simulated signal environment to support GPS antenna and receiver testing in a jamming environment to greatly reduce the need to conduct outdoor jamming testing and bridge the capability gap between outdoor testing and laboratory testing.

DESCRIPTION: Typical laboratory GPS testing lacks realism compared to live testing and laboratory test configurations do not precisely represent the motion of the orbiting GPS satellites with respect to the GPS receiver antenna being tested. The spatial relationships between the GPS satellites and the test item’s antenna is either ignored (when injecting the GPS signals into the receiver’s RF input port) or can only be approximated (tripods/fixed GPS satellite positions) for a short time period since the live GPS satellites are constantly in motion.

The indoor GPS satellite constellation antenna array will provide a complimentary test capability that supplements outdoor GPS EA/ET testing and can greatly reduce the amount of outdoor GPS EA/ET testing events. It will not completely replace outdoor test events but it will provide better realism than existing laboratory testing without the need for spectrum coordination at local, regional, and national levels associated with outdoor GPS EA/ET testing. It will allow for additional opportunities to test GPS systems under realistic conditions to better ensure vulnerabilities are not overlooked. This solution bridges the gap between laboratory and outdoor GPS EA/ET testing.

The position of individual GPS satellite (space vehicle) signal emissions in the indoor array will be dynamic to match the simulated GPS satellite relative position with respect to the receiver under test. The fact that the orbital movement of the actual GPS constellation has the effect of real-time motion makes this solution as realistic as possible. The system should work with a commercial-off-the-shelf (COTS) GPS signal simulator (for example the Spirent Federal Systems, Inc. Model 7790) to produce a realistic and dynamic GPS signal constellation at signal levels consistent with live GPS signals and separate them onto individual outputs (channels) that will feed the array. The array will be controlled by the GPS Simulator. The array should be capable of simulating the dynamic positions of at least 14 satellites (L1 & L2 frequencies at C/A-code, Y-code, and M-code).

The size of the array would need to be scalable to fit within a climate-controlled anechoic chamber. The antenna array should be able to be used within a chamber equipped with up to seven other antennas which would be providing threat signal generation. GPS Satellite Simulator Signals will be provided from a control room, adjacent to the anechoic chamber, where EA/ET Signal Generators, Test Control Computers, and Data Collection equipment will reside.

PHASE I: Determine feasibility and provide a prototype design for the Indoor GPS Satellite Constellation Antenna Array.

PHASE II: Develop and demonstrate a prototype Indoor GPS Satellite Constellation Antenna Array which can be integrated with a commercial-off-the-shelf (COTS) GPS signal simulator.

PHASE III DUAL USE APPLICATIONS: A commercial variation may include a complete system package, including the antenna array, EA/ET system generation and control, control and data collection systems and software, and test item positioner, ready for installation into a suitable chamber and connection to a COTS GPS simulator.



KEYWORDS: GPS, Antenna, Array, Position, Dynamic, Satellite, Simulator, Constellation, Attack, Emerging, Threat, Anechoic, Chamber, Global, Positioning, Controlled, Radiation, Pattern, Jamming, Indoor


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