Amateur radio enthusiasts in the US are targeting the potential lethal interference potential of a series of audio/video transmitters used on unmanned aircraft and marketed as amateur radio equipment.
In what it calls an ‘extremely urgent complaint’ to the US telecommunications regulator, the Federal Communications Commission (FCC), the ARRL national association for amateur radio said the transmitters use frequencies intended for navigational aids, air traffic control radar, air route surveillance radars, and global positioning systems.
In a January 10 letter to the FCC spectrum enforcement division, ARRL general counsel Chris Imlay said: “This is, in ARRL’s view, a potentially very serious interference problem, and it is respectfully requested that the products referenced…be investigated and removed from the marketplace immediately and that the importers be subjected to normal sanctions.”
ARRL said some of the transmitters operate on frequencies between 1,010 and 1,280 MHz. “These video transmitters are being marketed ostensibly as amateur radio equipment,” it said, “but of the listed frequencies on which the devices operate, only one, 1,280 MHz, would be within the amateur radio allocation at 1,240-1,300 MHz.”
Even then, ARRL said, operation there would conflict with a channel used for radio location.
ARRL said the use of 1,040 and 1,080 MHz, which would directly conflict with air traffic control transponder frequencies, represented the greatest threat to the safety of flight, adding that the use of 1,010 MHz, employed for aeronautical guidance, could also be problematic.
ARRL cited one transmitter and companion 6 W amplifier as an example of a problematic device being marketed in the US. Each costs less than $100 via the Internet and carries no FCC identification number.
“The target market for these devices is the drone hobbyist, not licensed radio amateurs. The device, due to the channel configuration, has no valid amateur radio application,” ARRL told the FCC. “While these transmitters are marked as appropriate for amateur use, they cannot be used legally for amateur radio communications.”
In the hands of unlicensed individuals, the transmitters could also cause interference to amateur radio communication in the 1.2 GHz band, ARRL contended.
ARRL added that the devices at issue lack proper FCC equipment authorisation under FCC Part 15 rules, which require such low-power intentional radiators to be certified.
“Of most concern is the capability of the devices to cripple the operation of the [air traffic control] secondary target/transponder systems,” ARRL said. “These illegal transmitters represent a significant hazard to public safety in general and the safety of flight specifically.”
ARRL also noted that some of the drones and associated equipment it has come across ‘are blatantly illegal at multiple levels’, with some drone TV transmitters described as ‘particularly alarming’.
“Rated at six times over the legal power limit, and on critical air navigation transponder frequencies, these devices represent a real and dangerous threat to the safety of flight, especially when operated from a drone platform that can be hundreds of feet in the air,” said the ARRL.
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