Sat-nav systems under growing threat from ‘jammers’

Technology that depends on satellite-navigation signals is increasingly threatened by attack from widely available equipment, experts say. While “jamming” sat-nav equipment with noise signals is on the rise, more sophisticated methods allow hackers even to program what receivers display. At risk are not only sat-nav users, but also critical national infrastructure.

A UK meeting outlining the risks was held at the National Physical Laboratory in Teddington. The meeting was organised by the government-funded Digital Systems Knowledge Transfer Network.

“The Achilles heel of GPS is the extremely weak signals that reach the receiver.” 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.

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.

The immediate solution to the problem is not clear, since the existing US GPS and Russian Glonass systems, and the forthcoming European sat-nav effort Galileo, are equally susceptible. Some at the conference suggested the relative security of the eLoran ground-based system that is already in place, but which existing consumer devices do not pick up. There is no reason to believe, however, that widespread adoption of eLoran or any other standard would preclude eventual jamming efforts to thwart it.

“Navigation is no longer about how to measure where you are accurately – that’s easy,” said Professor Last, a consultant engineer and former president of the Royal Institute of Navigation. “Now it’s all about how to do so reliably, safely and robustly.”

http://news.bbc.co.uk