Truckers (and others) using jamming devices to spoof trailer owners are causing problems for any receiver in range.
"The growing use of the devices could also torpedo any plans to introduce "pay as you drive" insurance or road toll systems if the vehicle owner was able to block communications with monitoring systems."
http://www.guardian.co.uk/technology/20 ... oads-risks
http://www.economist.com/node/18304246
"A secret network of 20 roadside listening stations across the UK has confirmed that criminals are attempting to jam GPS signals on a regular basis, a conference at the National Physical Laboratory, in London, will hear later today."
http://www.newscientist.com/blogs/onepe ... resen.html
http://www.gps.gov/spectrum/jamming/
http://www.novatel.com/assets/gajt/pdf/ ... -paper.pdf