As the term UAV (unmanned aerial vehicle) suggests, drones are supposed to fly
autonomously. And there’s the rub.
Unresolved questions for regulators and drone manufacturers are: a) how drones, while
flying, can maintain a reliable communication link with the ground for “command and control,” and b) if so, what communication spectrum is available.
drones are banned from flying at night and operating beyond line-of-sight. More important, under proposed rules, “drones can’t fly over personnel unrelated to
a [drone] project,” noted lobbyist Michael Drobac, executive director of the Small UAV
Coalition, during the radio show. In essence, “you are for the most part prohibiting the use
of drones for commercial purposes all together,” stressed Drobac.
The irony of the proposed drone regulation is that it permits “no robotization.”
“It’s as if we are putting some sort of manned overlay over what’s supposed to be an
unmanned system,” Drobac summed up.
The chief concern that emerged during the drone debate is the communication link between drone and pilot. The key question is whether drones need a dedicated communication
spectrum, or if Wi-Fi and cellular communication links suffice.
5GHz for dedicated drone communication
The drone industry will be getting two bands they can use for dedicated communication.
The drone industry will be getting two bands they can use for dedicated communication.
The World Radio Conference, which takes place every four years, has already approved —
in 2012 — “a spectrum around 5GHz” for command and control of UAVs, explained Jim
Williams, ex-FAA chief. This is a vacant band originally set aside for “microwave landing systems.” It’s
designed as an all-weather, precision landing system for aircraft. This spectrum has since been made obsolete by the wide availability of GPS, he said. Hence, it’s unused.
There is also “a small chunk of L-band around 1GHz” – originally set aside for aircraft to see ships at sea — now approved for dedicated drone
communication, he added.
During the radio show, Williams acknowledged that a handful drones today are permitted
to fly in the United States beyond line of sight and over people. But one of the requirements is that they have “reliable communication between a pilot and an aircraft.”
Those drones with permission to fly beyond line of sight, for example, depend on relatively
unregulated public frequencies used by Wi-Fi and mobile phones. Williams noted, “But those [frequencies] are set up in such a way that is not tremendously reliable, since when a lot of people are using it, your range drops.” In
some incidents, drones flew away when signals got jammed, he added.
Although drones are getting smarter and are dealing with [such potential problems], Williams insisted, “Reliable communication is a key for the [drone] industry.” For that, the world is
moving toward allowing drones to use a dedicated spectrum – within 5GHz – for their communications.
Qualcomm’s director of engineering Chad Sweet, countered: “Jim, it turns out, due to free
space properties, even with the antennas pointed at the ground the problem is seeing too
many towers and not too few.”
Obviously, the lack of cell signal availability worries drone users. Qualcomm’s Sweet said, “As the craft goes higher in rural areas, the coverage gets better.” However, he added,
“Existing networks would likely only be a stop-gap. A dedicated network would be needed longer term.”
There are alternative communication methods, but they aren’t great. “A satellite transceiver
is too heavy for small UAVs,” Sweet said. He opined that cellular networks might be
designed for all sorts of coverage scenarios. “Australia is a great example. They have sites
that go for up to 100 miles.”
Sweet concluded. “Cellular technology has been optimized for efficient multiple access over the last 30 years. It also has a nice property of being light weight. Regardless of spectrum
chosen, leveraging cellular technology will help quickly deploy UAV to ground
communications.”
没有评论:
发表评论