An anti-drone system developed by a trio of UK companies is to receive its first public test by America's Federal Aviation Authority (FAA), in an effort to protect airports from the risks of hobbyist's unmanned aerial vehicles. The system, called the Anti-UAV Defence System (Auds), looks like a mounted turret but instead of shooting drones out of the sky with bullets, it fires nothing more menacing than radio waves. Auds has three barrels of descending sizes, which act as a set of directional radio antennas. The portion of the radio spectrum used by drones is narrow, and so a short, loud (in electromagnetic terms) blast of energy is enough to completely prevent the drone from being able to communicate with its controller. Conventional multidirectional jamming systems work on drones, but have the downside of preventing the use of anything else in the area that relies on the same portion of the radio spectrum, such as mobile phones.