GNSS jam-proof test range ready for customer testing

A new dimension in real-world PNT testing has arrived. One of the most critical things to predict for chips, receivers and devices using alternative or back-up PNT technologies is how they will actually perform without GPS.

Filling this need, the U.S. Air Force 746th Test Squadron has declared Initial Operational Capability (IOC) for its new truth reference, the Ultra High-Accuracy Reference System (UHARS) at the White Sands Missile Range in New Mexico. Even when GPS — or any other GNSS system — is being completely jammed, UHARS provides extremely accurate positioning, navigation and time (PNT) over the large area that the system was designed to cover.

“Initial testing shows that UHARS delivers accurate independent PNT as good as, or better than, the Air Force’s current Central Inertial and GPS Test Facility (CIGTF) Reference System (CRS), so it is perfectly able to support current customer requirements,” said Dr. Jim Brewer, Chief Scientist of the 746th Test Squadron. “However, more data are required to tune the UHARS filter and optimize its accuracy to meet even tighter PNT requirements, which is our objective. When this is achieved, UHARS will deliver truth accuracy for next-generation military capabilities, and we will declare UHARS Full Operational Capability.”

“UHARS is a rack-mounted, tightly integrated system of improved navigation sensors, a data acquisition system (DAS) and a new post-mission Kalman filter, all of which need to work together,” explained John Cao, Technical Director of the 746th Test Squadron. “It’s working very well, but once we completely measure and characterize the individual components and then tune and validate the filter, the complete system will provide a significantly more accurate reference solution for future airborne and land-based test vehicles in navigation warfare environments where modernized and legacy GPS signals are jammed from friendly or hostile systems.”

To achieve these accurate reference solutions, UHARS requires a core Non-GPS Based Positioning System (NGBPS) component capable of operating and providing sub-meter position accuracy in a GPS-denied (jamming) environment. The NGBPS subsystem of the UHARS program employs a network of ground-based LocataLite transceivers and test vehicle receivers manufactured by the Locata Corporation. The Locata network deliver centimeter-level positioning and navigation as well as nanosecond-level synchronization, which may be useful for military applications requiring precise time transfer in GPS-denied environments.

White Sands Missile Range (WSMR) is a United States Army rocket range of almost 3,200 sq mi (8,300 sq km) in parts of five counties in southern New Mexico. It is the largest military installation in the United States.

The importance and uniqueness of the WSMR as GPS test facility spring from the fact that it is illegal to jam GPS elsewhere without a special permit. Thus it is extremely difficult to create a real-world test scenario for various GPS and other PNT devices, to see how they perform under denied or restricted circumstances. This is of critical importance for flight testing (UAVs and other avionics) for which the UHARS was primarily designed and optimized.

The LocataNet truth reference system can also provide a 2D solution to support ground vehicle testing.  Reportedly, the 2D solution, while also very good, has not yet been fully characterized. Once the filter has been fully tuned in this respect, WSMR could serve as a test facility for autonomous driving. There are many miles of paved highway on the WSMR, possibly in the hundreds of miles.

History of UHARS Development. Based on successful results of the original technical demonstration at WSMR in a real-world end-to-end environment, the USAF proceeded to the NGBPS production and fielding phase in 2012. The Locata Corporation was contracted to provide production ground transceivers and receivers, navigation algorithms required for data analysis and subject matter expertise. The TMC Design Corporation, the integrating contractor for this program, was tasked to develop the production hardware to house the Locata hardware, develop the command and control hardware and software, and field the production hardware at WSMR. The Locata network was fielded in September 2014, and its NGBPS capability is now core to the UHARS that is replacing the CRS.

“Our team is thrilled to be part of this historic USAF capability,” said Nunzio Gambale, CEO and co-founder of Locata Corporation. “Locata products developed and fielded by important commercial partners like Hexagon and Perrone Robotics routinely prove our technology is a game-changer for positioning over industrial-sized areas. However, leveraging Locata technology as the core non-GPS-based PNT solution over a vast military area when GPS is jammed instantly elevates our achievements into a completely new league. Clearly, we are witnessing the arrival of one of the most important technology developments for the future of the entire PNT industry.”

Customers wishing to leverage UHARS into their test programs should contact the 746th Test Squadron at (575) 679-2123 or 746ts.info@us.af.mil for scheduling information.