Delivering Unencrypted Assured PNT in GPS Denied Environments
Joshua Prentice, Applications Engineer, Orolia Defense & Security & Nick Newhart, Systems Engineering Supervisor, Orolia Defense & Security
Location: Ballroom A
Date/Time: Thursday, Jun. 15, 1:05 p.m.
The modern warfighter relies heavily on Assured Positioning, Navigation and Timing (APNT); however, as we’ve recently seen GPS denial is more prevalent than ever in combat areas. To support the warfighter Orolia Defense & Security (ODS) has worked with a US Department of Defense (DoD) customer to identify the need to provide APNT over RF to GPS reliant hardware in GPS denied environments. One solution to such a need is to use an APNT system that receives encrypted military codes coupled with an integrated IMU and transcode positional information into to a standard GPS L1 RF output. This allows non-keyed Commercial Off The Shelf (COTS) GPS devices to function in environments where GPS is denied.
Such a system has been tested in a real-world environment using a mobile test vehicle. The system consisted of an “all-in-one” APNT product that integrates a multi-constellation GNSS receiver , high performance internal time-base and inertial sensor, a GNSS time and frequency source with NTP/PTP time server, and GNSS spoofing and jamming detection with the addition of a RF transcoder to provide a GPS L1 RF output. The system was connected to a GPS RF splitter with a variable attenuator in line with the antenna input used to simulate various levels of GPS denial. The test was conducted both with and without a GPS antenna connected to test the functionality in both an ideal and a total GPS denied environment. The RF output of the system was connected to a COTS uBlox receiver. The USB output of the uBlox receiver was connected to a Windows PC using GNSS visualization software to provide data recording, analysis, and performance evaluation. The mobile test vehicle drove a route through Rochester, New York exercising various speeds and turning maneuvers.
The real-world test results demonstrated the RF output of the transcoder system matching the pre-transcoded solution and truth position to within 20 meters of accuracy. These results were observed in both GPS aided and GPS denied environments. A follow up real-world test was conducted at Fort Bragg with results demonstrating an accuracy to within 5 meters.
The demonstration will consist of a simulation of the real-world tests described above as well as a simulation of an “expanded” test that would be much harder to conduct in a live-sky testing environment. The simulation of the Rochester & Fort Bragg scenarios will focus on observing the results in real time using GNSS visualization software to compare the pre-transcoded and post-transcoded solutions to the simulated truth signal. Additionally, this simulation will eliminate some of the intricacies of conducting a real-world test such as a slightly misaligned IMU due to physical mounting of the system in the test vehicle. The second “expanded” simulation will emulate a much more intricate scenario beyond a total GPS denial. The scenario will be representative of some of the navigational warfare (NAVWAR) threats a warfighter may encounter such as stationary or dynamic jamming or spoofing using various techniques. Additionally, the expanded scenario would not be limited to only ground based vehicles and could include naval or airborne environments.
The capability to use non-keyed commercial GPS reliant hardware would greatly expand the options the warfighter has available in environments experiencing NAVWAR threats. Furthermore, the reduction of the number of keys and keying equipment necessary for operation would decrease the amount of management required to use such hardware. This demonstration would exhibit a potential solution that shows lots of promise for further iteration and improvements as it approaches the production-ready status.