GPS is the basis for satnav and a range of positioning services, as well as for many other technologies such as parts of the mobile phone networks. Although the use and sale of GPS jammers is illegal, it is not illegal to buy them. 

Since cell phone towers and some electrical grid systems use GPS signals for time-keeping, buy GPS jamming can throw them off and cause outages. "We're seeing a large number of low power devices which plug into power sockets in a car, These devices take out the GPS tracker in the vehicle, but they also create a 'bubble' of interference, sometimes out to up to 100 yards. They're illegal, so their quality control is generally not good. If you're the type who just may be the victim of undercover GPS tracking, you should give some serious thought to this one. Buy this GPS jammer knocks out ALL GPS logging GPS systems that may be operating. In your vehicle, and considering that it sports a 20 meter operating range, just about every automobile, including an 18-wheeler or limousine are covered.

Some are worried that we are now leaning too heavily on a technology that can all too easily fail – and it doesn't need a freak navy training exercise to cause havoc. Their biggest concern is a GPS jammer – a plastic device that can sit on car dashboards. These can be bought on the internet, and tend to be used by say, truckers who don't want their bosses to know where they are. Their increasing use has already caused problems at airports and blocked cellphone coverage in several cities. One jammer can take out GPS from several kilometres away, if unobstructed. No surprise, then, that researchers across the world are scrambling to find ways to prevent disastrous GPS outages happening.