DoT Report Evaluates GPS Back Up Technologies

11 Companies Evaluated…

By Kevin Dennehy, Location Business News

The U.S. Department of Transportation last month released its Complementary PNT and GPS Backup Technologies Demonstration Report that details technologies offering complementary service in the event of a GPS disruption.

The DoT’s Volpe Center, through a competitive acquisition process, selected 11 candidate technologies to demonstrate positioning or timing functions in the absence of GPS:

• Two vendors demonstrated Low Earth Orbit satellite PNT technologies, one L-band, one S-band Two vendors demonstrated fiber-optic timing systems, both based on the White Rabbit Precision Time Protocol (PTP) technology.
• One vendor demonstrated localized database map matching database, Inertial Measurement Unit (IMU), and ultra-wideband (UWB) technologies.
• Six vendors demonstrated terrestrial RF PNT technologies across, Low-Frequency (LF), Medium-Frequency (MF), Ultra-High Frequency (UHF), and WiFi/802.11 spectrum.

GPS expert and consultant Logan Scott said that while the report was excellent, and provides good guidance on technologies that may provide solid GPS augmentation, he cites several that were not demonstrated, notably 4G and 5G NR. “Both of which have significant, and demonstrated, timing and positioning capabilities independent of GNSS. The market will play a major role in deciding what actually will be available,” he said.

In addition, Scott said the report’s section that ranks performance sensitive and cost-sensitive bases has received a lot of industry attention. “While I don’t disagree with the general assessments, there is a considerable hazard in applying them blindly to select a national strategy,” he said.

Scott also questioned the testing of a technology’s resiliency. “None of the technologies was tested in an adversarial environment, e.g. jamming, cyber-attack, etc. A truly resilient system is a system of systems and the measure of its resilience is performance under attack and that is mostly a function of how well the systems are integrated,” he said.

Scott said that some of the technology is already offered in the marketplace. “Some — Satelles [LEO Iridium] — are available now for a subscription price. Others, NextNav [928 MHz beacons], perform extremely well, but will require significant infrastructure investment as contrasted with UrsaNav [eLoran], which provides lesser positioning capabilities, but can be deployed fairly inexpensively. Ultimately, the choices will be made by the market, he said.”

The DoT’s Volpe Center, through a competitive acquisition process, selected 11 candidate technologies to demonstrate positioning or timing functions in the absence of GPS:

• Two vendors demonstrated Low Earth Orbit satellite PNT technologies, one L-band, one S-band Two vendors demonstrated fiber-optic timing systems, both based on the White Rabbit Precision Time Protocol (PTP) technology.
• One vendor demonstrated localized database map matching database, Inertial Measurement Unit (IMU), and ultra-wideband (UWB) technologies.
• Six vendors demonstrated terrestrial RF PNT technologies across, Low-Frequency (LF), Medium-Frequency (MF), Ultra-High Frequency (UHF), and WiFi/802.11 spectrum.

NextNav’s TerraPoint terrestrial-based location product earned high ratings in the testing. TerraPoint works with a network of transmitters and altitude stations.

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