The UHARS Non-GPS-Based Positioning System (NGBPS)

Amid a growing concern about Global Positioning System (GPS) jamming in military areas of operation, testing GPS receivers and antenna systems in a GPSdenied environment is becoming increasingly important to Department of Defense (DoD) agencies. However, since GPS is often the “gold standard” position, navigation and time information that serves as a truth reference during field and flight testing, conducting tests in an area that has no GPS availability because of intense jamming makes it difficult to compare observed position and navigation data to a valid truth source. Moreover, to evaluate system performance with appropriate statistical significance, the reference system against which test results are measured needs to be significantly more accurate than the system under test. Therefore, when the system under test is GPS itself, this poses an interesting problem. Figure 1: CIGTF Reference System (CRS) For more than a decade, the 746th Test Squadron (746 TS), also known as the Central Inertial and GPS Test Facility (CIGTF), has met this requirement by employing its CIGTF Reference System (CRS). The CRS (Figure 1) is a system of navigation sensors that evaluates combinations of its subsystem measurements in an extended Kalman filter/smoother algorithm to produce an optimal reference trajectory. Delivering sub-meter accuracy in non-GPS-jammed environments and meterlevel accuracy in GPS-jammed environments, the CRS is arguably the most accurate reference system in the DoD. However, many future DoD weapons systems are projected to require tighter navigation accuracies in GPSdenied environments, and as these requirements improve, the reference system against which they are evaluated must improve accordingly. To meet these test and evaluation reference requirements in a GPS-denied environment, a new reference system is needed. Answering this call, the 746 TS embarked on the development of the Ultra High Accuracy Reference System (UHARS), a next generation reference system that meets test and evaluation reference requirements for future navigation and guidance systems. UHARS consists of a rack-mounted, tightly integrated system of improved navigation sensors/subsystems, data acquisition system (DAS) and a new post-mission reference trajectory algorithm. 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. Achieving these accurate reference solutions requires a Non-GPS Based Positioning System (NGBPS) subsystem capable of operating and providing sub-meter position accuracy in a GPS-denied (jamming) environment. The NGBPS portion of the UHARS program employs a network of ground “LocataLite” transceivers and test vehicle receivers (also called “rovers”) manufactured by the Locata Corporation. Although the NGBPS uses Locata’s standard commercial LocataLites and rovers, meeting the demanding UHARS accuracy and distance requirements of better than 18 centimeters accuracy over a 30 mile range in a flight configuration necessitated custom transmit antennas, external signal amplification, custom navigational software for flight, as well as the addition of a centralized command and control (C2) capability. Distribution Statement A: Approved for public release. Distribution is unlimited. PA number: 96TW-2014-0106 Based on successful results of the technical demonstration at the White Sands Missile Range (WSMR) in October 2011 that prototyped the architecture in a real-world endto-end environment, the USAF proceeded to the NGBPS production and fielding phase. To this end, the 746th Test Squadron awarded two sole-source contracts to Locata Corporation and TMC Design Corporation, respectively. The Locata Corporation was contracted to provide production ground transceivers and rovers, navigation algorithms required for data analysis and subject matter expertise. The TMC Design Corporation, the Locata Technology Integrator (LTI) for this program, was contracted 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. This paper details the NGBPS production effort to include an overview of the design, development and network integration.