Tethered drones are being developed and tested as an alternative or back-up to satellite communications
Unmanned aerial vehicles (UAVs) could provide a repeater station for line-of-sight broadband connectivity or be used as base stations for ship communications.
Dragonfly Pictures Inc (DPI) is developing drones that can be tethered up to 150 m above a vessel, or any floating structure, acting as an antenna for line-of-sight communications, or as part of a maritime long-term evolution (LTE) or 3G/4G communications system.
In April 2018, it demonstrated how its unmanned multi-rotor aerial relay (UMAR) drone could be launched, landed and manoeuvred on a tether from a moving vessel.
DPI is testing an environmentally hardened version of UMAR with the US Navy this month. “We will be doing qualitative tests on the environmental limits of UMAR to understand its ability to recover in certain sea states,” says DPI president Michael Piasecki. “It has operated in 35-40 knot winds so far in tests.”
UMARs could be connected to a land-based communication point either through a subsea fibre optic cable or a line-of-sight system. It could then be a router for broadband communications to surrounding vessels or shipping.
Mr Piasecki tells Maritime Digitalisation & Communications that UMAR would have a range of 32-40 km at a height of 150 m, depending on environmental conditions.
“It could be an alternative or a back-up to satellite communications, or provide a local area network,” he says.
UMAR could be a useful tool for communicating with unmanned surface vessels during defence and commercial operations. “Our drone could extend the communications range in a command and control scenario,” he says. The US Navy thinks a UMAR will extend the operational range of surface UAVs up to three times.
“Because it is tethered, the drone receives power from the vessel and can remain up for weeks at a time, except in gale-force winds,” Mr Piasecki continues. “It can be brought down, recovered and then relaunched quickly and will automatically follow the host ship.”
DPI’s UMAR will be as secure as satellite communications. “It is hackable-resistant so totally secure,” he says. “As cyber security and higher levels of autonomy impact the maritime industry, our technology could provide back-up communications in areas of high shipping frequency,” says Mr Piasecki.
UMAR could also be a back-up for telecommunications as a backhaul method for mobile phone communications at sea.
Its potential applications include a communications base station in offshore oil and gas and renewables operations. Perhaps a UMAR could be tethered at greater heights for longer distance communications from offshore drilling rigs or remote oil production infrastructure.
Or drones could be tethered to buoys and become communications station in approaches to busy ports or shipping lanes.
For further distances, multiple tethered drones may be used. “Drones could be daisy-chained for long distance communications,” says Mr Piasecki. “Our technology would be useful in extending the range of unmanned surface vessels.”
The latest tests involve an UMAR tethered to a US Navy mine-hunting vessel stationed in the Middle East Gulf.
Mr Piasecki also considers drones a possible navigation aid. “It could have a payload of sensors to aid visual awareness, with day and night cameras and radar,” he says.
Further tests and development will produce a commercial product in the future for defence, offshore and merchant marine communications.