Satellite-navigation signals under increasing threat from ‘jammers’

LONDON - Scientists have said that satellite-navigation signals is under increasing threat from ‘jammers’.

According to BBC News, while “jamming” sat-nav equipment with noise signals is on the rise, more sophisticated methods allow hackers to program what receivers display.

At risk are not only sat-nav users, but also critical national infrastructure.

“GPS gives us transportation, distribution industry, ‘just-in-time’ manufacturing, emergency services operations - even mining, road building and farming, all these and a zillion more,” said David Last, a consultant engineer and former president of the Royal Institute of Navigation. But what few people outside this community recognize is the high-precision timing that GPS provides to keep our telephone networks, the internet, banking transactions and even our power grid online,” he added.

“Satellite failures, though dramatic, are not the main problem. The Achilles heel of GPS is the extremely weak signals that reach the receiver,” he said.

Each satellite in a sat-nav constellation is putting out less power than a car headlight, illuminating more than a third of the Earth’s surface at a distance of about 25,000 km.

What that means, and what has brought this group of policy-makers, academics and industry figures together, is that the signals can be easily swamped by equipment back on Earth.

This can be done unintentionally by, for example, pirate television stations, or with a purpose in mind.

Military systems have been doing this “jamming” - flooding an area with a signal at the GPS frequency - for years in a bid to frustrate enemy navigation systems.

But small jamming devices are increasingly available on the Internet.

Low-power, hand-held versions can run for hours on a battery and confuse sat-nav receivers tens of kilometres away.

Higher-power versions can do far worse, and at both GPS and mobile phone frequencies.

What is more, receivers can be “spoofed” - not simply blinded by a strong, noisy signal, but fooled into thinking their location or the time is different because of fraudulent broadcast GPS signals.

“You can now buy a low-cost simulator and link it to Google Earth, put on a route and it will simulate that route to the timing that you specify,” said Professor Last.

“A GPS receiver overcome by it will behave as if you’re travelling along that route,” he said.

The approach still costs in the thousands and is the preserve of what Professor Last calls the “real techies”, but he guessed that the tools could be in the hands of criminals within a year or wo. (ANI)