Tag: GNSS

The United Kingdom’s spectrum agency, Ofcom, is seeking comments on its proposal to issue licenses for broadcasting eLoran signals and services. This initiative comes, it says, after the agency was “…approached with a request to authorize use of the 90-110 kHz spectrum for the provision of a long-range navigation system, based on eLoran technology.” Issuing licenses could be a way to treat all interested parties fairly.

After briefly describing the importance of positioning, navigation, and timing (PNT) services to modern life, the Ofcom request for comment observes: “Satellite-based PNT systems like the Global Positioning System (GPS) can be susceptible to interference and can be vulnerable to space weather events. The eLoran technology provides a terrestrial-based alternative … which could in [the] future act as a supplementary or back-up system to GPS. [I]t has the potential to support innovation in the delivery of resilient PNT.”

This rationale is quite similar to that cited by other governments operating Loran-like systems around the world.

Until now, with a few minor exceptions, only government entities and those working on their behalf have been authorized to use the frequency. Such licenses would authorize holders to broadcast eLoran in the 90 kHz to 110 kHz band, which is the portion of spectrum reserved internationally for radio navigation.

From October 2014 to December 2015, the UK had an operational eLoran network serving the waters off its east coast and authorized for maritime use. That system was discontinued when France and Norway bowed to pressure from supporters of Europe’s Galileo system, which was still in development. The UK Ministry of Defence still broadcasts a single eLoran signal from Anthorn, UK, that can be used as a wireless timing source.

Several other nations currently broadcast some version of Loran in the 90 kHz to 110 kHz band. These include PNT systems operated by South Korea, Saudi Arabia, Russia and China. Reports indicate Iran is also broadcasting in the spectrum, though other details remain unclear.

Unconfirmed reports from amateur radio operators in the United States seem to indicate that testing of Loran-like signals in the 90 kHz to 11 0kHz band has been conducted in North America periodically over the last 10 years.

Until now, the UK has only formally authorized eLoran and the frequency for maritime use. Observers in the UK say this Ofcom initiative will almost certainly expand that to its use everywhere and for multiple applications, such as timing for critical infrastructure.

Ofcom says, “[d]eployment of eLoran in the UK could complement existing PNT services, particularly in locations where there is poor GPS coverage or weak signals, like tunnels or deep inside buildings. eLoran could also provide resilience (i.e., back-up) for satellite-based systems against interference, jamming and spoofing, thereby aiding protection of key national infrastructure…”

This Ofcom notice may be the first official move toward encouraging one or more entirely commercial eLoran services.

Commercial wide-area PNT services capable of protecting critical infrastructure and national economies have long faced an uphill battle, though.

Several industry leaders have commented that “it’s impossible to compete with free GNSS!”

The same leaders have also criticized the U.S. government for not “walking the talk” when it comes to resilient PNT. At a U.S. Department of Transportation meeting last year they urged the government to not just tell others, but to set an example and protect itself with resilient PNT services. Doing so, they said, would show industry and users the government is serious and instill confidence that commercial services were reliable and would be sustained.

Yet, experts cite a “chicken and egg” problem.

“The government can’t subscribe to services that don’t exist, and companies can’t stand up and provide nation-wide services without having an anchor-customer first,” according to an industry insider.

To solve this dilemma, public-private-partnerships have been proposed over the years in both the UK and the United States. To date, a willing “public” or government partner has yet to be identified for either nation.

This might be changing in the UK government with growing awareness about the limitations of and threats to GNSS and other space systems. While a national strategy for PNT has been promised for years and is yet to be published, a cross-government PNT office has recently been established.

“The UK is in a great position to lead the world on resilient PNT,” said one observer at a recent Royal Institute of Navigation event. “The key is working with GPS and other GNSS, while at the same time ensuring your nation has its own sovereign system independent of space. We (in the UK) have deep expertise and experience at the GLA (General Lighthouse Authority) with eLoran, and we have a superb tech economy. Britain could be the world’s leading producer of a resilient PNT tech stack that includes eLoran transmitters, receivers that use GNSS, eLoran, and other signals or phenomena, and all the supporting gear and IP (intellectual property) to make it all work.”

“Realizing that vision will take a bit more government leadership than just issuing a few broadcast licenses, though,” they said.