As we become ever-more reliant on GPS, the prospect of it going down seems increasingly worrying.

　　Almost half a century ago, the US Department of Defense started working on an experimental project to launch a series of satellites into space to make it possible to pinpoint any location on Earth.

　　Fast-forward 47 years, and the Global Positioning System (GPS) is everywhere and in everything from the activity-tracking applications in our smartphones to the navigation systems found in airplanes.

　　And it became part of the US government's plan, too: in 1983, the Reagan administration declared that it would effectively guarantee and provide GPS for both military and civilian purposes.

　　Reagan couldn't predict, at the time, that engineers would develop chips cheap and sophisticated enough to power more than five billion smartphones across the world, all fitted with GPS and contributing to a global dependence on the technology.

　　Jamming happens when too much noise is broadcast by third parties on the same frequencies used by satellites to send data to receivers on the ground, which in turn calculate their location by determining their distance from the satellite.

　　By sending radio signals on those frequencies, or on frequencies neighboring those used by technology, jamming effectively shuts down GPS navigation.

　　The US Federal Communications Commission (FCC) is well aware of the issue. It has taken steps to punish the use of jammers gps, which are small devices that send out radio signals on the same frequencies as GPS to override or distort satellite signals.

　　In Southern California, the technology is used to study the movement of tectonic plates and assess the likelihood of earthquakes. GPS is used for precision agriculture, to map fields and increase productivity while better spreading the use of fertilizers.

　　In other words, protecting GPS frequencies in the modern world is critical. For that reason, the US Department of Transportation last year published an assessment on "GPS adjacent band compatibility, an analysis of the frequencies neighboring GPS spectrum and of whether they should be used for commercial purposes.

　　And with Amazon now planning to deploy a fleet of drones to deliver packages straight to our doors, it is likely that more portable jammer devices will be seen flying around sooner rather than later.