SBIR-STTR Award

Precision navigation is key to future warfighting doctrine. The ability to accomplish extremely accurate en-route, targeting, and terminal operations based upon precision navigation has become an assumption of battle planning and warfighting operations. The Global Positioning System (GPS) is the critical element for precision navigation. Fully exploiting its capability while ensuring the integrity of the navigation solution is the precision navigation imperative. Differential GPS has been selected by the DoD's Joint Precision Approach and Landing System (JPALS) program for implementation of the JPALS. The DoD recognizes that certain attributes of current, commercial differential GPS system require augmentation to establish navigation integrity for mission critical operations. The DoD's Multi-function Information Distribution System (MIDS) provides a secure communication link and relative navigation capability that can augment GPS for improved integrity and survivability of precision navigation operations. Phase I Tasking that investigates MIDS as a potential communication link for differential corrections, examines the optimal integration of MIDS, GPS, and INS data for a more robust nav solution, and explores the use of ground-based MIDS in conjunction with GPS as a secure back-up for differential GPS-based precision approach and landing systems is provided.

U.S. Coalition Military Link-16 networks, as implemented in Joint Tactical Information Distribution System (JTIDS), F-15 Fighter Data Link (FDL) and NATO Multifunctional Information Distribution System (MIDS) terminals, provide Anti-Jam cryptographically secure communications, crypto participant identification and time-of-arrival (TOA) ranging based navigation. Military Global Positioning System (GPS) provides accurate navigation based on TOA ranging to multiple satellites. Both of these systems are mandated on front line Tactical Weapon Systems (air and surface), Sensor and Command and Control military platforms. This effort proposes to use the best aspects of both Link-16 and GPS to provide secure, anti-jam accurate navigation to military users of these platforms with minimal impact (minimal cost) to the platforms. Many sources have identified inexpensive, effective jamming threats to GPS receivers. Most threats attack the low rate C/A access code that the military receivers also use for cold starts. Link-16 could be used to provide the jammed GPS receivers with the time and navigation data plus crypto keys needed to allow direct P(Y) military code rapid acquisition which will make the GPS receivers tolerant to a higher level of jamming. In addition, the Link-16 TOA measurements combined with GPS TOA measurements could help GPS coast through jamming periods. This program addresses how to accomplish both of these as well as demonstrate and quantify the level of the navigation benefits achievable. A Navy effort in 1999 (JTIDS Time-Aiding of the Global Positioning System) showed the benefits achievable with direct P(Y) code acquiition through time aiding from JTIDS Link-16. Phase I of the SBIR program reached the conclusion that the navigation data to be transferred from an unjammed GPS receiver set, the security levels and the anti-jam protection are all compatible with both Link-16 and GPS equipment architectures. It was identified that interfaces between the two systems must be developed and tested for the Link-16 aid to the GPS receivers. It was also shown in Phase I that there are some Link-16 protocols that will limit the precision of an integrated Link-16/GPS navigation solution. Phase II will dramatically showcase the navigation improvements possible through demonstrations at the SPAWAR Systems Center GPS Facility and will identify to the development commands, the upgrades required to achieve the navigation benefits that result from the synergism between Link-16 and GPS.

Benefits:
The primary benfit of this multi-phased SBIR program is the implementation of high-performance, robust and cost effective interfaces and processing to enhance the performance and capacity of tactical military navigation systems. The results of this program will directly benefit the Military GPS navigation community by providing a low cost method to improve the jamming performance for those platforms with both Link-16 and GPS on-board. Other government and civilian users will benefit from the extension of current research that will be published in journals such as the IEEE MILCOM transactions and civilian applications of the concept (with a commercial data link other than military Link-16) will improve the reliability of Civilian SATNAV, of Lacal Area Augmentation System (LAAS) and of Wide Area Augmentation System (WAAS).

Keywords:
GPS Link-16 MIDS JTIDS Anti-Jam Navigation Secure Communication Integrated Navigation