The Pulse

Australia & United States (December 07, 2021)


Russia’s recent threat that it could blow up all the GPS satellites with its new anti-satellite technology (ASAT) should come as no shock to those following space-related events. In the past, China shot down one of its own Low Earth Orbit Satellites (LEOS) using a medium-range ballistic missile, and the United States used a modified antiballistic missile to shoot down one of its own spy satellites. Blowing up satellites, solar flares, ever increasing hazards from “space junk”, and thousands of new satellites in the launch queue all make space a congested and increasingly dangerous place.

Locata Corporation and Ursa Navigation Solutions, Inc. (“UrsaNav”) today announced a Technology Partnership specifically aimed at providing resilient PNT (Positioning, Navigation, and Timing) solutions to national governmental and commercial interests globally. Combining Locata’s high-accuracy local-area and UrsaNav’s very wide-area PNT produces a potent solution which lessens any nations’ dependency on easily disrupted and increasingly vulnerable space- based signals.

Read Full Press Release:

November 2021 – There is a lot of coverage of (e)Loran in the latest NIST Technical Notes #2187 and 2189, available at these links: and Full disclosure, although NIST did not reach out to UrsaNav to provide direct input/comment to their publications (not unusual), they used a lot of UrsaNav text, graphics, and pix in their discussions of Loran and eLoran. These documents are an incredibly rich source of timing information for the public and private sectors. NIST (and USNO) has always been a fan of eLoran, and Loran-C before it, so we were glad to see they still consider it a valuable alternative to GNSS. As you may recall, Loran-C was a DOD system so its timing was “sourced” from the USNO (via “hot clocks”) and the USNO monitored its relationship to UTC and provided notices to users of any offset(s) and drift rates. This is similar to the function that the USNO provides for GPS.

Note that NIST did not mention that (e)Loran can operate in a Two-Way Low-Frequency Time Transfer (TWLFTT) mode. TWLFTT can provide a terrestrial, layered time-transfer network wherein time is transferred between any two (e)Loran transmission sites that can receive each other’s signals. UrsaNav tested this theory as part of our first CRADA with the USCG Research and Development Center, which started in 2012. Note that TWLFTT is completely “sky-free”.

Note also that there has been a lot of “hay” made from (e)Loran competitors that there are no miniature LF receivers. This is simply not true. Even at the 60kHz signal that WWV uses (40 kHz lower than Loran), timing receivers are easily chip-scale. See page 148 of NIST 2187. Further miniaturization is not an issue of science or technology; it’s simply a matter or market demand.

There were a couple of statements in NIST 2187 that we found extremely troubling, and which we are bringing to the attention of the authors:

“Beginning in the early 1990s, the Loran-C stations were synchronized with GPSDCs, with the Hewlett-Packard GPS Smart Clock used as the primary reference at many station sites after about 1997. This direct synchronization to GPS did, of course, invalidate the premise that Loran-C, and the proposed eLoran system that followed, were GNSS independent, which made them unsuitable as a GPS backup system.”

(e)Loran stations in North America were NEVER directly linked to GPS. All three Primary Reference Standards at transmitting sites operated independently of each other, and independently of any remote timing source. The (e)Loran system was designed specifically with no direct connection to any external timing source, whether it be GNSS, TWTT, or fiber. All of these sources might be monitored, but there is an air-gap between them and the triple ensemble of cesium-based Primary Reference Standards. The system was purpose-built to not allow an external timing reference to be able to “walk” the station’s timing away from UTC. What the authors might have misinterpreted is that we did start installing Time-of-Transmission Monitors (TTM) at the transmitting sites in the late 1990’s and early 2000’s. The TTM included a GPS Disciplined Clock (GPSDC), but the system was not directly connected to the station timing generation equipment, and was not used to control the transmissions. The TTM only reported the difference between the transmission times and UTC, as referenced against a local, survey-grade GPSDC. (e)Loran has never relied on GPS as its timing source.

November 2021 – UrsaNav and its CEO, Charles Schue, are cited several times in the GPS World article entitled: “eLoran: Part of the solution to GNSS vulnerability”. UrsaNav has always considered eLoran a key component of a service provider’s “Resilience Triad” that delivers Resilient PNT (RPNT), and also a major component of any PNT System-of-Systems. Another necessary component is GNSS. It is time to consider that a triad might not best represent the RPNT model of the future. Certainly, two very important components are eLoran and GNSS, but other solutions include fiber, a Metro Beacon System (MBS, e.g., Locata), and even 5G or R-Mode (VHF). From a user’s perspective, their PNT “sensor ensemble” should include GNSS and eLoran for wide area coverage, an MBS for local area coverage, and a good on-board clock for timing applications or inertial navigation system for positioning. Fiber is a great option for point-to-point solutions that do not require wireless capabilities. See:

July 2021 – A collaboration of the Oscilloquartz (an ADVA company) grandmaster clock and our own eLoran receiver technologies yields a robust and reliable backup for GPS and other GNSS, and could be used to provide an assured position, navigation, and timing (PNT) service. Harnessing ADVA’s flexible OSA 5420 Series, designed with assured PNT (aPNT) technology, UrsaNav has shown that eLoran can provide a new layer of protection and significantly boost timing resilience and security. See:

July 2021 – UrsaNav’s CEO, Charles Schue, was cited in the First Fix segment of the July issue of GPS World where he stated that “the only replacement for a GNSS is another GNSS” and for his definition of alternative PNT: “An alternative PNT solution is one that is readily available; provides an easy and seamless transition to/from the primary or other alternatives; allows continuity of operation at a possibly degraded, yet usable, accuracy, availability, integrity, or continuity; and is dissimilar enough from other alternatives to withstand the effects that might be affecting the primary solution.” He also contributed to the Alternative PNT Q&A article.

April 2021 – UrsaNav continues to deliver exceptional products and services, even during the dreadful global Pandemic. As an example of how things can go with a committed customer, we are completing a High-Power RF transmitting station site project that was started the summer before the COVID Pandemic. This high-power radio station is located in difficult terrain and includes very complex construction, technology, and security elements. As the pictures below can attest, our management of the project has kept things moving even in incredibly difficult times. We are working with almost 50 vendors, partners, and government organizations and are close to making the site operational. Our customer has been 100% involved, committed, and supportive from starting the project through helping ensure its success. Together, we have overcome all of the travel and supply chain issues that have plagued projects since COVID impacts began back in November 2019. We have carefully followed all CDC guidelines and successfully balanced the needs of our customers, vendors, and partners, with those of our staff. I am confident that, working with you, we can perform similarly for all of your PNT service delivery or user experience needs.

High Power RF Transmission Site - Winter
High Power RF Transmission Site - Spring

April 2021 – UrsaNav is pleased to announce its continued support of the South Korean Ministry of Oceans and Fisheries (MOF) in their deployment of a terrestrial eLoran PNT system to complement and back up GPS/GNSS. UrsaNav was the key technology provider to the South Korean Government for their eLoran IOC system, and we look forward to supporting MOF as they expand their eLoran system to cover all of their sovereign territory and maritime exclusive economic zone. South Korea is a first mover in the provision of a comprehensive system-of-systems approach to PNT services that protect their critical national infrastructure and their citizens. Please see Terrestrial navigation system ready for use in S. Korea to cope with jamming and electric warfare ( for additional information.

March 2021 – The US Patent and Trademark Office (USPTO) has approved UrsaNav’s Private eLoran patent (United States Patent Application 20190377055). Private eLoran is a new and innovative breakthrough in terrestrial PNT technology that provides secure, un-spoofable, and virtually un-jammable PNT signals. Private eLoran provides a secure co-primary alternative, or complementary backup, to GPS/GNSS for individual nation-states or collaborative regions. Private eLoran significantly reduces the risk/reward equation for those who wish to jam or spoof PNT signals, especially those that are space-based. With this new capability, service providers can now deliver fully-open or fully closed solutions, or a combination of both. This new patented technology is another leap forward in UrsaNav’s progressively innovative eLoran and LFPhoenix™ products and services.

March 2021 – UrsaNav’s CEO, Charles Schue, and Board of Advisors Member, Dr. Wouter Pelgrum, have the pleasure of announcing that the long awaited Two-Volume Set entitled “Position, Navigation, and Timing Technologies in the 21st Century, Volumes 1 and 2: Integrated Satellite Navigation, Sensor Systems, and Civil Applications, Set 1st Edition” is now available. Chapter 41 provides historical and current information on “Navigation with Low-Frequency Radio Systems”, and also provides a peek into what may be coming in the future. Given the authorship of this chapter, it naturally includes a comprehensive study of Loran-C and Enhanced Loran systems. We are extremely honored to have been selected to participate in this incredibly important and comprehensive project that showcases all the various technologies necessary for a resilient PNT ecosystem. The work is available from Wiley ( and other fine outlets.

March 2021 – UrsaNav comments on the recently released “Complementary PNT and GPS Backup Technologies Demonstration Report – DOT Report Number DOT-VNTSC-20-07 dated January 2021.”

In June 2020, UrsaNav completed delivery of an eLoran Transmission system at a temporary location near Incheon, ROK.
For additional information:

Find us at the International Defence Exhibition & Conference (IDEX), Abu Dhabi, UAE – February 17-21, 2019.

In collaboration with the General Lighthouse Authorities of the UK and Ireland (GLA), UrsaNav provided an article for the Royal Institute of Navigation’s Navigation News Magazine entitled: “The Resilience Series: Ground-Based Navigation Systems”. Please read the excerpted article here and be sure to sign in to read it on the RIN’s website:

Find us at the ION International Technical Meeting (ITM) / Precise Time and Time Interval (PTTI) Conference in Reston, VA – January 28-31, 2019.

Charles Schue appointed to the Institute of Navigation (ION) Council – January 28, 2019.

Charles Schue co-authored the Low Frequency Radio Navigation chapter of the Position, Navigation, and Timing Technologies in the 21st Century: Integrated Satellite Navigation, Sensor Systems, and Civil Applications book edited by Jade Morton, Frank van Diggelen, James Spilker, Bradford Parkinson, with associate editors Sherman Lo and Grace Gao. The book was recently announced on Wiley Publications’ website.

ROK eLoran Contract Award – The Korea Research Institute of Ships and Oceans Engineering (KRISO) has awarded UrsaNav, through its agent, Dong Kang M-Tech, a contract to supply an eLoran Transmitter Test Bed System in the Republic of Korea. Read More

UrsaNav is pleased to be working with Spectracom on the development of this exciting new timing product. It demonstrates the market’s demand and the importance companies have started to place on resilient timing solutions for critical operations and infrastructure. Read More