GPS is ubiquitous and an essential component of many critical things — and, as New Scientist points out, GPS reception can be knocked out in a wide area by an inexpensive device, thanks to the fact that GPS signals are comparatively quite weak.

[GPS jammers] 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. […]

Though illegal to use in the U.S., U.K. and many other countries, these low-tech devices can be bought on the internet for as little as $30. Sellers claim they’re for protecting privacy. Since they can block devices that record a vehicle’s movements, they’re popular with truck drivers who don’t want an electronic spy in their cabs. They can also block GPS-based road tolls that are levied via an on-board receiver. Some criminals use them to beat trackers inside stolen cargo. “We originally expected that jammers might be assembled by spotty youths in their bedrooms,” says [consultant David] Last. “But now they’re made in factories in China.”

Via @gpstracklog.