Radio Navigation, Dodging Government GPS

Radio navigation set to make global return as GPS backup, because cyber by Sean Gallagher.

From the post:

Way back in the 1980s, when I was a young naval officer, the Global Positioning System was still in its experimental stage. If you were in the middle of the ocean on a cloudy night, there was pretty much only one reliable way to know where you were: Loran-C, the hyperbolic low-frequency radio navigation system. Using a global network of terrestrial radio beacons, Loran-C gave navigators aboard ships and aircraft the ability to get a fix on their location within a few hundred feet by using the difference in the timing of two or more beacon signals.

An evolution of World War II technology (LORAN was an acronym for long-range navigation), Loran-C was considered obsolete by many once GPS was widely available. In 2010, after the US Coast Guard declared that it was no longer required, the US and Canada shut down their Loran-C beacons. Between 2010 and 2015, nearly everyone else shut down their radio beacons, too. The trial of an enhanced Loran service called eLoran that was accurate within 20 meters (65 feet) also wrapped up during this time.

But now there’s increasing concern about over-reliance in the navigational realm on GPS. Since GPS signals from satellites are relatively weak, they are prone to interference, accidental or deliberate. And GPS can be jammed or spoofed—portable equipment can easily drown them out or broadcast fake signals that can make GPS receivers give incorrect position data. The same is true of the Russian-built GLONASS system.

Sean focuses on the “national security” needs for a backup to GPS but it isn’t North Koreans, Chinese or Russians who are using Stingray devices against US citizens.

No, those are all in use by agents of the federal and/or state governments. Ditto for anyone spoofing your GPS in the United States.

You need a GPS backup, but your adversary is quite close to home.

The new protocol is call eLoran and Sean has a non-technical overview of it.

You would have unusual requirements to need a private eLoran but so you have an idea of what is possible:

eLoran technology has been available since the mid-1990s and is still available today. In fact, the state-of-the-art of eLoran continues to advance along with other 21st-century technology. eLoran system technology can be broken down into a few simple components: transmitting site, control and monitor site, differential reference station site and user equipment.

Modern transmitting site equipment consists of a high-power, modular, fully redundant, hot-swappable and software configurable transmitter, and sophisticated timing and control equipment. Standard transmitter configurations are available in power ranges from 125 kilowatts to 1.5 megawatts. The timing and control equipment includes a variety of external timing inputs to a remote time scale, and a local time scale consisting of three ensembled cesium-based primary reference standards. The local time scale is not directly coupled to the remote time scale. Having a robust local time scale while still monitoring many types of external time sources provides a unique ability to provide proof-of-position and proof-of-time. Modern eLoran transmitting site equipment is smaller, lighter, requires less input power, and generates significantly less waste heat than previously used Loran-C equipment.

The core technology at a differential eLoran reference station site consists of three differential eLoran reference station or integrity monitors (RSIMs) configurable as reference station (RS) or integrity monitor (IM) or hot standby (RS or IM). The site includes electric field (E-field) antennas for each of the three RSIMs.

Modern eLoran receivers are really software-defined radios, and are backward compatible with Loran-C and forward compatible, through firmware or software changes. ASF tables are included in the receivers, and can be updated via the Loran data channel. eLoran receivers can be standalone or integrated with GNSS, inertial navigation systems, chip-scale atomic clocks, barometric altimeters, sensors for signals-of-opportunity, and so on. Basically, any technology that can be integrated with GPS can also be integrated with eLoran.
Innovation: Enhanced Loran, GPS World (May, 2015)

Some people are happy with government controlled services. Other people, not so much.

Who is determining your location?

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