From maps on car dashboards and mobile phones, to road tolls, aviation and marine navigation systems and even financial exchanges, much of modern life relies on Global Navigation Satelite Systems (GNSS) that use satelite signals to find a location or keep exact time.

The familiar Global Positioning System (GPS) set up by the U.S. government, and GLONASS, a similar Russian system, were both built for military purposes but are now available to anyone with a device that can receive a signal. The European Union, China and India are setting up similar systems.

Experts are worried about havoc that could be caused if GNSS signals were illegally jammed, said Bob Cockshott, a director at Britain's ICT Knowledge Transfer Network - an initiative funded by the UK's national innovation agency - which is hosting a conference in London on Wednesday.

The problem was illustrated in 2009 when navigation systems at Newark Airport in the United States began suffering daily breakdowns brought about by a truck driver with just a cheap, low-powered jammer in his vehicle going by on a nearby road.

"We have moved on from a potentially threatening situation to a real danger that we must address now," Cockshott said.

JAMMING INCIDENTS

Widely available on the internet, jammers are not illegal to own but are illegal to use. Just how widespread they are is unclear but research to be unveiled at the London conference will reveal monitors at one location in Britain recorded 60 individual jamming incidents over six months.

Criminals have also embraced the technology, Cockshott said, with cases where thieves had hijacked vans carrying high value goods after jamming their GPS and cellphone systems.

"Certainly toughening the law to make it illegal to possess one is certainly a step that can be taken. But before that, we need to know just how many of them there are and how widespread the problem is," he told Reuters.

Some devices confiscated by police possessed "monstrous" transmission power when compared with the weak signal emitted by satellites and that had serious implications, Cockshott said.

Researchers in 2010 issued low-level jamming from the coast to see the effect on shipping in the English Channel, one of the world's busiest shipping lanes.

They noted that ships veered off course without their knowledge, gave out false readings to other vessels about their position so risking collisions, and caused communications systems to fail, preventing crew talking to coastguard.

Cockshott said there were now serious concerns "that we are going to see a disaster" in the Channel within the next decade.

Nor do the jammers require great expertise to make. "You could imagine the bored teenager, hacker personality builds one of these things just to see what would happen," he said.

"SPOOFING" THREAT

While jamming poses an immediate threat, a potentially more serious risk is posed by "spoofing" - creating false GPS signals to alter users perceptions of time or location.

Until recently, while theoretically possible, such technology was not seen as viable or affordable.

However, Todd Humphreys, a specialist in GPS technology from the University of Texas, told Reuters he had developed the first GPS civilian spoofer, a "very powerful" device which cost under $1,000 to assemble.

He said spoofers could be attractive to anyone who could make money from fooling GPS systems, from fishermen wanting to work in forbidden waters, motorists dodging road charges to those wanting to cheat the world's financial trading markets.

"The financial exchanges that depend so much on their own credibility and on people's trust of the markets could be damaged fairly significantly by routine manipulation of the time stamps that they apply to all of their transactions," he said.

"That could cause turmoil in the markets and people to pull out of the market automatically because their algorithms are designed to pull out when something looks fishy."

Unscrupulous traders could also use a time discrepancy of just a few milliseconds to make large gains via inter-market arbitrage. Like jammers, they could be easy to put together.

"It's not outside the capability of any other smart graduate student in GPS or GNSS across the world," he said. "And it's not outside the capability of any kind of sophisticated terrorist organisation."

No fully-fledged spoofing attacks have yet been reported, although an Iranian engineer claimed to have used the technique to down a U.S. stealth drone last December.

"It was within the realm of possibility and that was the real story," said Humphreys who studied the engineer's report.

Whether the authorities are ready for such a threat is unclear. A spokeswoman for London's Stock Exchange said the exchange was unaware of such a threat and Humphreys said while the U.S. Department of Homeland Security had conducted a risk assessment last year, more needed to be done.

"I think the U.S. is finally taking this seriously," he said. "But I haven't seen any serious money put down on spoofing counter measures or even jamming counter measures in the United States."

(Editing by Peter Graff)

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