On Nov. 4, 2019, the U.S. Department of Transportation awarded contracts to 11 companies to demonstrate their technologies’ ability to act as a backup for GPS.
We wanted to know a bit more about what each of them were going to demonstrate, so we asked each for an explanation. Most provided just that, so much of what appears here is in their own words. A couple of companies sent us a whole lot more than 100 words and two did not respond. For those, we did our best with the materials they sent us and other publicly available materials.
Wi-Fi, Cellular, Ultra-Wideband
PhasorLab plans to demonstrate its Hyper Sync Net (HSN) technology as a backup to GPS-based PNT solutions. HSN is a self-organizing mobile mesh network capable of maintaining high-precision time (<<1 ns) and frequency (<<1 ppb) synchronization throughout the whole network as well as an instantaneous 3D locational map of the whole mesh network requiring as little as a single master reference node.
The HSN can be deployed either as a set of fixed reference nodes providing time and positioning references to other mobile UE clients, which is like a terrestrial version of GPS, or as a private ad-hoc mobile mesh network where all members are expected to be mobile.
Skyhook Technology’s system is powered by an immense database — created and maintained by Skyhook — that contains more than five billion geolocated access points and 200 million cell base station IDs, enabling it to accurately locate phones and devices worldwide. The user is not required to be connected to a Wi-Fi network for the system to work. The scan will simply detect Wi-Fi access points in the local area based on signals sent periodically (or on demand) according to the IEEE 802.11 specifications. Many devices will acquire information on as many as 100 access points in the surrounding area. Skyhook’s Wi-Fi positioning system (WPS) will compute an estimated end-user location based on each of the signal sources independently, and compute an optimal hybrid location estimate from all sources.
Fiber/Network
OPNT’s Global Terrestrial Timing Service (GTTS) provides GPS-independent timing-as-a-service over global fiber-based networks. Trading off cost versus service-level agreement (SLA)-backed accuracy, standard network connectivity offerings and bidirectional fibers are combined to meet application needs. As will be demonstrated with simulations of National Institute of Standards and Technology (NIST) and the two U.S. Naval Observatory (USNO) clocks, OPNT’s fully redundant solution receives its core Coordinated Universal Time (UTC) timing directly from the non-maskable interrupts (NMIs).
The demonstration will include sub-nanosecond stability with fault detection and glitchless recovery. Using the precision-timed fiber base, OPNT will also demonstrate precision monitoring of wireless signals with continuous, real-time corrections to keep the wireless transmissions and its local timing source in sync.
Seven Solutions’ core technology is called White Rabbit and was born at CERN. In this demonstration, Seven Solutions plans to showcase the performance of this technology, both on local and wide-area deployments, and explain the capabilities in terms of interoperability (integrating multiple synchronization technologies, i.e. IEEE 1588 PTP, NTP, PPS, 10-MHz clocks), scalability and resiliency. The goal is to provide a reference technology that can provide very stable time references over fiber in GPS-denied scenarios as a backup source or to complement other PNT solutions that need timing distribution at their core.
eLoran
Hellen Systems’ team said it is excited by its recent contract award to perform a GPS back-up demonstration for the Department of Transportation. Its team plans to demonstrate advanced eLoran technologies and offer resilient PNT services. Its next-generation solution will include a solid-state eLoran transmitter from Continental Electronics Corp. integrated with advanced timing and frequency products from Microsemi, a Microchip company. Hellen Systems also plans to deploy its proprietary receiver and reference systems developed by Microsemi.
Hellen Systems and program integrator L3Harris will manage the demonstration, with Booz Allen Hamilton providing technical and engineering leadership.
UrsaNav supplies eLoran, LFPhoenix and low-frequency technology for very wide-area, GPS-independent, PNT data and frequency services. UrsaNav was selected by the Volpe Center to demonstrate wide-area UTC time synchronization and distribution utilizing the former Loran site in Wildwood, New Jersey. UrsaNav will provide innovative new eLoran technology at the site in Wildwood to broadcast a UTC-synchronized eLoran signal. The demonstration will be conducted at one of the Volpe Center demonstration sites at Joint Base Cape Cod in Massachusetts or the Langley Research Center in Langley, Virginia. Either site can be utilized in the demonstration as eLoran signal transmissions from the Wildwood site can easily cover 700 miles or more.
Serco recently acquired Alion’s Naval Systems Business unit. This included a group working in New London, Connecticut, that has previously worked with and published on eLoran. While we did not get a response from Serco to our inquiry, eLoran is likely the technology the company will demonstrate.
Satellite
Globalstar-Echo Ridge’s system is based on Augmented Positioning System (APS) technology that uses ordinary signals from communications satellites (not special positioning/navigation signals, such as those from GPS satellites) to produce accurate position and timing information in compatible user devices. No new infrastructure is needed; Globalstar’s constellation of 24 low-Earth-orbit (LEO) satellites and Echo Ridge software and compatible devices at the user end provide the building blocks for the APS-based system. APS technology has been successfully demonstrated in diverse environments and incorporates multiple features to assure accurate PNT information under circumstances that can challenge or disable GPS/GNSS technology.
Satelles provides unique timing and location solutions delivered over the Iridium constellation of 66 LEO satellites. These timing and location signals are available anywhere on Earth without the need for local infrastructure, making the system perfect for complementing GPS and other location-based technologies.
Unlike standard GPS, these high-power signals can reach into many building structures. Most importantly, Satelles has customized the Iridium signal-in-space to provide a location-specific signature that can reliably prove (or authenticate) the location of a mobile device or other equipment, while being virtually impervious to spoofing and other attacks.
TRX Systems’ NEON Personnel Tracker provides ubiquitous 3D location, tracking and mapping. (Screenshot: TRX Systems)
Other
TRX Systems is the developer of NEON GPS-denied location solutions, delivering 3D location and mapping for dismount personnel where GPS is not available or is unreliable — including indoors, underground, in dense urban areas, and where GPS is found to be erroneous. NEON delivers ubiquitous, low-cost, GPS-denied location by using advanced sensor fusion, ranging and patented dynamic mapping algorithms that improve safety and situational awareness for military, public safety and industrial personnel.
NextNav’s Metropolitan Beacon System (MBS) is a 3GPP-compliant, terrestrial network of long-range broadcast beacons, transmitting a “GPS-like” signal in licensed spectrum in the sub-GHz range. The combination of an on-board atomic clock and the ability to self-synchronize allows the system to operate independent of GPS and provide full PNT services in its footprint. The ability to integrate the MBS signal in mass-market GPS and LTE chipsets can provide a seamless ability to provide full PNT services in the presence and absence of GPS. Because of its terrestrial nature, MBS is able to work indoors, in urban environments and outdoors; for barometer-equipped devices, MBS also enables floor-level altitude determination.