Once powered up, a typical GPS jammer can be fully operational in under 20 seconds. GPS jammers - devices that block signals for the Global Positioning System satellites that orbit the earth - have been around for many years, but just as their usage has soared thanks to the inclusion of GPS tracking technology in most modern smartphones, so the use of GPS jammers has also soared.
According to Professor Charles Curry, the managing director of Chronos Technology, a company which has carved out a successful niche in the GPS jamming remediation and analysis business, this surge in jamming is the direct result of the number of Web sites - mostly in China - that sell these devices for as little as £80.00.
In a recent analysis, he says, his team found more than 60 Web sites - mainly located in China - offering a wide variety of handheld multi-functional jammers, including units that can block GPS and cellular transmissions.
"One unit we bought recently for US$ 180 [about £120] was found to block all GPS signals for a range of several hundred metres," he told his audience at a presentation held this week at Counter Terror Expo.
"Back in 2004, we installed a 10 watt jammer in central London and were amazed to find out that there were GPS problems in Heathrow, Stansted and Gatwick airports," he explained.
Todays jammers - which operate at around half a watt and have a range of half a kilometre - are now being used for a wide variety of criminal and allied acts, ranging from `white van man who wants to `skive off without his company knowing, all the way through to higher-powered units used to help steal high-end cars and expensive lorries plus their cargo.
In the case of lorries, he says, the criminals will drive behind and close to the vehicle, and then follow it for several miles, before staging a hijack, confident in the knowledge that - when the company calls in the police to trace the vehicle - its last known position could be many miles off its real position.
"This is what we call JAC, short for Jamming Assisted Crime, and it is most definitely on the increase," he said, adding that, once powered up, a typical jammer can be fully operational in under 20 seconds.
Contrary to what many people think, he went on to say, GPS jammers are easily detectable by police and other IT professionals, as they shine out like a light in the middle of the countryside at night.
This is why, he explained, most criminals will only use the jammers when they have to, and will try to switch them off as quickly as possible, as they know they are standing out like a lighthouse on a dark night in the country.
Having said that, he says, their usage as a means of blocking asset tracking in industry is on the rise, as criminals latch on to the fact that quite complex pieces of kit can be stolen using a jammer, then their usage can only increase.
Most jammer detectors, Professor Curry says, vary in their capabilities. Lower-cost handheld units, he adds, are non-directional, whilst more complex - and expensive units - can be used to triangulate the offending user.
One of the growing trends in criminality, he told his audience, is the use of jammers to block the asset trackers used in high-value plant kit, such as large-sized plant lorries and steamrollers, as whilst these vehicles have on-board asset tracking system, a simple GPS jammer can allow the vehicle to be stolen outside of working hours with relative ease.
Is there a method of blocking GPS jammers?
Professor Curry replied that some work is being carried out in the field of null field transmissions, which can generate a signal lobe that coincides with the location from which the jammer is being used, but the signal power levels involved are quite significant, and a commercial solution is still some way off.
Given that it is not specifically illegal to have a GPS jammer in your possession, he predicts that the usage of GPS jamming technology is likely to continue to increase in the months ahead.