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Drone technology holds great promise. But a secure communication to control and determine the location of drones still remains a challenge. Today’s drones are typically controlled by regular remote control. The limited range of this solution, however, severely restricts the scope of where drones can be used. An alternative possibility would be to exchange information using data channels of the mobile network. But this option also has its flaws which, as things stand, rule out reliable, commercial use on a large scale, according to

Another solution would be to set up a drone-specific infrastructure for controllers to communicate with the devices. But in addition to the complexity and expense, this would involve, the radio resources required for this endeavor are scarce.

Scientists from Fraunhofer Institute for Telecommunications HHI in Berlin, however, have developed a solution that is stable, affordable, not limited in range, and essentially, ready to go: controlling drones using the voice channels in mobile networks.

“A major advantage is that – unlike the data connections – the voice channels are available almost everywhere and they’re highly reliable, too,” explains Tom Piechotta, a research associate at Fraunhofer HHI. “Even in areas where there is only a limited data connection or even none at all, there is usually still network coverage for voice channels.”

An additional benefit is the near absence of any extra costs involved because no new infrastructure or special contracts with network providers to prioritize data connections are required.

Drone control works on the basis of two-way communication: controllers on the ground transmit commands to the device, and the device returns information on its position, altitude or battery status. “Relatively speaking, the control commands and positioning information are fairly small amounts of data, but they must nevertheless be transmitted reliably,” says Piechotta. “We convert the commands into audio signals, in much the same way as modems used to. A small module on the drone then translates the audio signal back into a command. Transmitting the information in this way is extremely favorable given that it works in real-time and is highly resilient to failures and connection disruptions.”

When out of sight, the drone’s location can be visualized using an online map service such as Google Maps. Also shown on the map are the drone’s position and altitude, which the device transmits in real-time. Another option is to install sensors on the drone to detect and avoid unexpected obstacles.