Federal Radionavigation Plan Touches on NDGPS, eLoran

May 27, 2015  - By
Image: GPS World

News courtesy of CANSPACE Listserv

The 2014 Federal Radionavigation Plan, just released from the U.S. Department of Transportation, touches on funding for the Nationwide Differential GPS and the use of eLoran as a precision timing alternative.

The plan is signed by the Secretaries of Defense, Transportation and Homeland Security, and released by the DOT Office of the Assistant Secretary for Research and Technology. A PDF of the document has been posted to the NAVCEN’s website.

Nationwide Differential GPS (NDGPS). The nationwide differential GPS (NDGPS) service augments GPS by providing increased accuracy and integrity using land-based reference stations to transmit correction messages over radiobeacon frequencies. The service has been implemented through agreements among federal agencies including the Coast Guard, DOT and the Army Corps of Engineers, but a decision has not yet been made on funding beyond FY2016:

“The Department of Homeland Security, in coordination with the Department of Transportation, is analyzing the future requirements for the NDGPS to support investment decisions beyond Fiscal Year (FY) 2016. Future investment decisions might include maintaining NDGPS as currently configured, decommissioning NDGPS as currently configured, or developing alternate uses for the NDGPS infrastructure. Contributing factors to these decisions are: (1) the U.S. Coast Guard change in policy to allow aids to navigation (ATON) to be positioned with a GPS receiver using Receiver Autonomous Integrity Monitoring (RAIM), and to allow USCG navigation in all waters using the WAAS receiver; (2) limited availability of consumer grade NDGPS receivers; (3) no USCG DGPS carriage requirement on any vessel within U.S. territorial waters; (4) the Presidential Directive turning off GPS SA; (5) continuing GPS modernization; and (6) the Federal Railroad Administration’s determination that neither NDGPS, nor High Accuracy NDGPS, are requirements for the successful implementation of Positive Train Control.”

eLoran for Timing. eLoran is mentioned in the plan only briefly, in the following excerpt about precision timing alternatives:

“For precise timing applications, chip-scale atomic clocks are now available from at least one company, and others have active research and development programs in the United States and abroad. The U.S. Coast Guard has established a Cooperative Research and Development Agreement to assess a high-power wireless alternative for providing precise time using U.S. government facilities such as mothballed Loran-C sites, upgraded to eLoran capability. If successful, this effort would offer another solution suitable for integration with GPS, or use as an independent complement to GPS, that could together provide highly available and precise timing for many applications.”

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