Locata Passes Critical Design Review Milestone for U.S. Air Force Ground-Based Positioning System
Locata Corporation announced it has successfully completed the Critical Design Review (CDR) contract phase for a Locata network which will enable the USAF to deploy a new ground-based, centimeter-accurate “truth-reference level” positioning system for use in GPS-denied environments. The USAF 746th Test Squadron (746TS) awarded Locata a multi-year contract for this project in July 2010, and the CDR was the last milestone to be met before the USAF committed to a technology demonstration in the USA. Locata’s Non-GPS Based Positioning System (NGBPS) – sold commercially as a LocataNet – will provide accurate positioning when GPS is jammed over 2,500 sq. miles (6,500 sq. kilometers) of the White Sands Missile Range (WSMR) in New Mexico.
The project’s most significant milestone to date, completion of the CDR demonstrates the company’s detailed LocataNet design as capable of meeting the non-GPS based positioning component of the 746TS Ultra-High Accuracy Reference System (UHARS). The contract now moves to an initial deployment over approx 600 sq. miles (1,500 sq. kilometers) at WSMR for further testing in October 2011.
Locata brought together many years of engineering experience and numerous Locata technical “firsts” to deliver NGBPS technology to the 746TS in these flight trials, including:
- demonstrating Locata’s autonomous, nanosecond-accurate TimeLoc synchronization capability when Locata transmitters (LocataLites) are placed up to 30 miles (50 km) apart;
- demonstrating that TimeLoc can be “cascaded” from one LocataLite to another in multiple “TimeLoc hops” of at least 30 miles (50 km) per hop;
- showing LocataLites can be successfully attached to various high-powered transmit amplifiers to deliver much longer ranges, yet continue to maintain accurate TimeLoc;
- demonstrating that Locata receiver tracking loops perform adequately under demanding “military-spec” speed, acceleration and jerk stresses;
- demonstrating Locata receivers acquiring and tracking Locata positioning signals at a range of at least 30 miles (50 km);
- showing navigation solutions with tropospheric models that adequately mitigate the large tropospheric errors encountered by terrestrial signals at these long ranges;
- demonstrating a carrier-phase “truth-reference” solution to the 746TS of <18 cm at a range of 30 miles (50 km) with a PDOP <3 and;
- developing, manufacturing and demonstrating new transmitter and aircraft antennas to provide both satisfactory network coverage to the WSMR test area and adequate gain and multipath mitigation capabilities for the aircraft. The new antennas were developed in collaboration with Cooper Antennas Ltd of Marlow, Buckinghamshire, UK.
Dr. John Raquet, Director of the Advanced Navigation Technology Center at the Air Force Institute of Technology and Satellite Chairman for The Institute of Navigation, joined six other positioning experts from the 746TS at Locata’s Australian Headquarters to conduct the CDR. Over a four day period, the group conducted a meticulous review and analysis of real-world data gathered by Locata during two flight trials over a 600 sq. mile (1,500 sq. kilometer) LocataNet deployed around Cooma airport in southern New South Wales. Following this analysis, Locata produced a final CDR Report which was tendered, and accepted. Locata has now been advised officially that the NGBPS CDR objectives have been achieved and the CDR is formally closed.
The 746TS is scheduled to present a paper on the NGBPS program at the Institute of Navigation (ION) GNSS 2011 Conference in September in Portland, Oregon. The paper will outline the history of the 746TS positioning capabilities and present results from relevant Locata flight tests.