E-Loran: The PNT Technology which is more Accurate and Less Vulnerable


The shipping industry involves high value assets and movement of valuable cargo on a daily basis. Ships use GPS (Global Positioning System) and other similar devices that rely on sending and receiving satellite signals, which are vulnerable to jamming by hackers.

About 90 per cent of world trade is transported by sea and the stakes are high in increasingly crowded shipping lanes. Unlike aircraft, ships lack a back-up navigation system and if their GPS ceases to function, they risk running aground or colliding with other vessels.

When the weather is bad, and during fog, the visibility is low. During this time, ships depend entirely on GPS for their navigation. If the GPS goes wrong, the potential for accidents is very high. Losing these systems can become a big problem when visibility is an issue and on busy shipping routes such as the English Channel.

There is an increasing awareness in the maritime world that no single system can provide PNT (Position, Navigation, Time) resiliently under all circumstances. At this moment, GPS (with augmentations) is used on most commercial vessels, and in many cases, integrated into systems, which were not expected to require or use GPS-derived position or time.

Though the GLONASS, Galileo, BeiDou and other GNSS systems provide some resilience, the underlying (satellite) technology remains the same, only providing relatively weak signals from space.

Of late, the evolution of earth-based navigation technology – ‘eLoran’ (Enhanced Loran) has been revolutionary. ELoran is the latest and proven series of low-frequency, LOng-RAnge Navigation (LORAN) systems, which meets the accuracy, availability, integrity and continuity performance requirements for maritime harbour entrance and vessel movements.

It is a low-frequency radio navigation system that operates in the band of 90 to 110 kHz. It allows GNSS users to retain the safety, security and economic benefits of GNSS even when their satellite services are disrupted.

ELoran uses pulsed signals designed to allow receivers to distinguish between the ground-wave and sky-wave components. This way, the eLoran signals can be used over very long ranges without fading or uncertainty in the time-of-arrival (TOA).

Ships are more reliant on a range of electronic devices to operate. This includes – software to run the engines, complex cargo management systems, automatic identification systems (AIS), global positioning systems (GPS) and electronic chart displays and information systems (ECDIS).

Jamming or disrupting GPS systems creates significant problems. In April last year, South Korea said that around 280 vessels had to return to port after experiencing problems with their navigation systems. A cyber-attack that hit a major marine liner’s IT systems in June 2017 had disrupted port operations across the world.

Hacking leads to failure of multiple systems – navigation systems, emergency systems, the clocks and the automatic identification system (AIS), which transmits a ship’s location to other nearby ships so they appear on the radar. Jammers affect GPS receivers on ships at sea to the horizon at about 30km.

With the eLoran technology in place, the shipping industry can be protected from jammers and hackers extensively for the foreseeable future. With three eLoran transmitters in good geometry, eLoran can provide sub-10 meter (95 per cent probability level) horizontal positioning accuracy and UTC synchronization within 50 nanoseconds.

The United States, Britain and Russia have already explored adopting versions of the technology, which works on radio signals. Other nations have either begun, or are exploring, similar projects. Together with Loran transmitters in England, France, Germany, Norway and Denmark, the differential eLoran reference stations provide better than 10-meter positioning accuracy at seven ports and port approaches along the English and Scottish east coast.

Nine nations are operating Loran-C or eLoran stations, including Russia and China. According to industry sources, the Republic of Korea, India and the Kingdom of Saudi Arabia are pursuing the installation of eLoran technology or upgrading their Loran-C technology to eLoran.

US engineer Brad Parkinson, known as the ‘father of GPS’ said that ELoran is only two-dimensional, regional, and not as accurate, but it offers a powerful signal at an entirely different frequency. “It is a deterrent to deliberate jamming or spoofing (giving wrong positions), since such hostile activities can be rendered ineffective,” said Parkinson.

To be precise, eLoran, as an internationally standardised positioning, navigation, and timing (PNT) service, will be soon implemented over a wide range of applications, as an independent, dissimilar, complement to Global Navigation Satellite Systems (GNSS). PNT users will be capable of retaining the safety, security, and economic benefits of GNSS, even when their satellite services are disrupted or when using eLoran in areas where GNSS in not available.

(References: Linkedin, CNBC, Express.co.uk, GPS World)

Sea News Feature, October 11


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