GPS Jamming

Warning on increased risk of GPS jamming

Cheap GPS jammers bought off the internet could seriously disrupt busy shipping lanes writes Craig Eason in Lloyds List Tuesday 13 October 2009

NAVIGATION experts are warning about the increasing availability of jamming devices that can render ships without key satellite positioning data.

Experts claim that even the forthcoming European Galileo constellation is no safer from malicious or accidental jamming, as it will use a similar range of frequencies as existing global navigation satellite systems. These include the US Global Position System constellation, Russia’s Glonass and China’s Compass systems.

Electronic transmitters — some smaller than a mobile phone — can be used to disrupt the GPS signals from satellites, leaving equipment such as electronic navigation tools and mandatory vessel monitoring systems all but useless.

There have been official trials that have demonstrated the impact of this simple, readily available equipment, which can be used maliciously to disrupt shipping. These include tests last year by Trinity House, the UK’s lighthouse authority responsible for aids to navigation. It managed to send a jamming signal from a UK headland and destroy GPS signals on one of its vessels 20 nm away.

Satellite and communications consultant David Last advises organisations such as the Royal Institute of Navigation about the increased risk of malicious jamming.

He said UK police were aware of an escalated criminal tendency to use jammers bought off the internet. They are being used to help steal high-value cars or expensive freight loads with built-in GPS tracking.

In a number of cases, the small jammers were plugged into the cigarette lighter socket of a car that was then put in a container and shipped out of the country. Consequently, those onboard the vessel were unaware of the presence of an active jammer that could produce GPS signal distortions.

When technical experts at UK’s General Lighthouse Authority performed jamming trials on one of its vessels, Pole Star , last year they were shocked at the impact onboard the vessel.

GPS provides position, navigational direction and, most vitally for many industries as well as maritime, time keeping. It is a key input into the Electronic Chart Display and Information Systems that the shipping community has been told to install on all its ships over the next nine years.

Timing gives Ecdis the accurate positions, helps drive the gyro compasses and is the key position and time producer for the data included in mandatory transmissions in automatic identification signals and long-range identification and tracking.

“We had AIS tracks doing 1,000 knots over land,” said Trinity House deputy master Jeremy de Halpert.

The test led to confusion and pandemonium on the bridge of the vessel. “All the alarms went off — not just some, but nearly all of them,” he added. Vessel systems relying on the GPS signal became unreliable and the level of automation on the vessel threatened to leave it out of control.

Rear Adm De Halpert said the bridge team found it difficult to navigate and respond to the bridge alarms and systems losses at the same time. The gyro compass was erratic, so there was no accurate heading indication, the auto pilot threatened to change course and the crew were concerned that the engine systems would be impacted.

This test occurred when the crew was expecting the disruption and there was more than one person on the bridge. A solitary navigating officer on the bridge of a modern vessel could be at a loss responding to the continual alarms, rather than attempting to understand the cause of the disruption.

Jamming is not always deliberate. There have been incidents of unintentional jamming — one of the Trinity House vessels reported a fault in the VHF aerial that inadvertently jammed the GPS signal until it was discovered two days later.

GPS jamming also has implications for banking and trading, which are reliant on precise time keeping. Other systems that could be seriously adversely affected by a jammed GPS signal are the National Grid, mobile phones and hospitals.

In 2007, there was a major jamming incident at the port of San Diego. A US Coast Guard investigation found that it was caused by a US Navy vessel, which was taking part in a communications exercise. It inadvertently jammed the GPS signals for two hours across the harbour and city.

“Because GPS is the principal system for synchronising telecommunication systems, they lost 150 mobile phone cells around the city, as well as affecting all the ships in the port,” said Prof Last.

Hospital pagers failed to work and aviation GPS systems were also said to be affected, he added.

Experts say GPS equipment is susceptible to jamming because of the weak signal ground receiving stations, such as a mobile phone network or a ship navigation system, obtain from a distant satellite. The Trinity House trial used a jammer producing only 1.5 watts to create a 20 nm disruption zone.

Prof Last, Rear Adm de Halpert and other experts are concerned that the shipping industry is placing a huge dependence on a sole means of position determination that is proven to be easily fallible, yet are refusing to take the risks seriously.

“We know there is a major vulnerability. It is a bit like the first computer viruses, which were out there and no one was worried,” said Prof Last.

Trinity House plan to run a similar GPS disruption test in December in northeast England, in a bid to make industry and government more keenly aware of the issues, said Trinity House and General Lighthouse Authority director of research and radio navigation Sally Basker.

This test would use a much smaller jamming device to prevent systems off the vessel being affected, but will demonstrate the severity of the situation, Ms Basker added.

While the Trinity House tests have used relatively small jamming devices to minimise disruption, Prof Last warned that the bigger systems on the market could cause disruption over an area of more than 300 sq km.

If such a signal is used maliciously close to Dover it could create havoc in one of the busiest shipping lanes in the world and could render the AIS signals received by the local traffic control centres as meaningless.

The proof that GPS is fallible also comes with reports that the US-controlled GPS constellation is likely to suffer over the next five years as the number of active satellites drops by 20% during a renewal and maintenance period. This could render a drop in the accuracy of the signals.

Trinity House, with support from the French and Norwegians, has been promoting e-Loran as a useful back-up for GPS.

While Rear Adm de Halpert recognises that GPS is normally both reliable and accurate, he is pushing to get countries to support the development of e-Loran, a land-based system that sends out a signal similar to GPS.

Although any radio signal could be jammed, according to Ms Basker, it would be much harder to jam an e-Loran signal as it is 10,000 times stronger and cannot be drowned out as easily as the much weaker GPS signal.

“It is the difference in power between a 100 watt light bulb and a rock concert in your back garden,” Ms Basker added.

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