Congress mandated movement in December 2017.
U.S. National PNT Architecture from a 2007 Department of Transportation report, updated in 2017. (Graphic: U.S. Department of Transportation)
The U.S. Department of Transportation (DOT) says it will implement a terrestrial timing system to complement and back up GPS signals, and plans to demonstrate the new system “towards the end of the calendar year.”
The demo is anticipated to include a range of technologies, including among others local positioning systems such as Locata and NextNav, wide-area coverage by eLoran, and — though the parameters of DOT’s mandate specified terrestrial backup — space-based signals furnished by Satelles.
The statement came in response to an inquiry in March from the House of Representatives’ Transportation and Infrastructure Committee concerning progress on a GPS Backup Technology Demonstration that was mandated in December 2017. Although funds were appropriated for the project, committee chair Peter DeFazio of Oregon saw little to no evidence of work being done, and so required a status report.
DOT issued a Request for Information (RFI) on May 3, with a due date of June 3. The RFI asked for “readiness-level six” technologies (bearing demonstrated results in a relevant environment) “capable of providing backup positioning, navigation, and/or timing services to critical infrastructure in the event of a temporary disruption to GPS.
“This demonstration effort also is expected to encompass technologies capable of providing complementary PNT functions to GPS by either expanding PNT capabilities, including cross checks, or extending them to GPS or Global Navigation Satellite System (GNSS)-denied or degraded user environments.”
The DOT said it is “interested in leveraging PNT service technology initiatives.” Possibly, the agency intends to contract for a service rather than build a new system.
Congress first required DOT to establish an operational terrestrial timing system to back up GPS signals, then expanded that definition to include positioning and navigation services.
Systems or services, or combinations thereof, must now provide all three functions.