Original URL: http://www.theregister.co.uk/2009/10/08/uav_radios/
US clears the air for flying drones
Remote controlled metal needs radio
Remotely controlled aircraft need frequencies in which to operate - and quite a lot of them, if the latest US submission to the World Radiocommunications Conference is to be believed.
While the military might play fast and loose with unmanned aerial vehicles - to the point of crashing one or two  - civilians tend to be more risk-averse. If we're really going to see more than 5,000 remotely-controlled lumps of metal in the air over the next ten years, they're going to need spectrum in which to operate - and rather more than the 8MHz that Ofcom has suggested might be available.
The next World Radiocommunications Conference isn't until January 2012, but the debates have already started and the FCC has been busy pushing its 32 proposals (pdf ) for a better radio future, including a couple asking for more radio frequencies to be allocated for UAV use.
The Teal Group reckons there'll be 5,500 civilian robots flying around the USA by 2018, though most of those will be government-owned with commercial companies moving into the business and putting a lot more robots into the air, around 2020.
Right now, civilian drones can't share airspace with those containing fleshy bits, but that's going to have to change if the expected number of robots take to the air - and if the robots are going to share airspace then the radio frequencies used become very important. The wrong kind of interference does a lot worse than drop a phone call.
Civilian UAVs come in two types: those controlled by line-of-sight radio connections, and those using relayed signals from low-earth-orbit satellites. Mark Lewellen, chair of the ITU-R working party sub-group on Unmanned Aircraft Systems (as they are formally known), told PolicyTracker  that studies estimate line-of-sight requirements at 34MHz, with bird-bouncing signals consuming another 49MHz of bandwidth.
That allows for decent safety margins, though UK regulator Ofcom has suggested  that two blocks of 4MHz (at 872 and 917MHz) might be suitable for unmanned flying vehicles. We assume Ofcom is referring to small-scale robots rather than anything capable of downing a jet liner.
The key requests from America are for the bands 112-117.975MHz, 960-1164MHz, and 5000-5030MHz be allocated to line-of-sight operations, with 37-38GHz getting legislated protection from interference for satellite-based systems.
The Conference is still more than two years away, so don't expect anything to happen soon: Mark's sub-group is still working on draft documents for presentation at one of the many preparatory meetings already taking place in Geneva ahead of the conference, but if robots are going to come off the battlefield and into commercial use then we'll all be grateful for internationally cleared spectrum in which they can operate. ®