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Beyond Visual Line-of-Sight UAV & Remote Pilot Communications

Leveraging SyTech RADIUS for Beyond-Line-of-Sight VHF and Tactical Radio Communications.

Unmanned aerial vehicles (UAVs) have become an integral part of many industries, including agriculture, construction, and photography. However, for commercial UAVs to comply with Federal Aviation Administration (FAA) regulations, they must offer a means of communication with ATC and registered aircraft while airborne. Beyond-Visual-Line-of-Sight (BVLOS) radio communications provide a solution to this challenge. SyTech RADIUS has enabled UAV operators to comply with FAA regulations while communicating on VHF or tactical radios for non-line-of-sight range extension. 

The SyTech RADIUS nPoint RoIP over Satellite Communications

The SyTech RADIUS solution enables remote pilots to communicate via radio-over-IP to the airborne radio installed on the UAV. The communications link allows the remote pilot to communicate with ground control while complying the FAA frequency management. The encompassing network creates a Radio-over-IP (ROIP) environment unbound by distance, platform, or location.

The RADIUS Solutions incorporates four key subsystems: (1) the Radius nPoint installed on the uncrewed aircraft, (2) the satellite or alternative IP link, (3) the Radius Distribution Service, and (4) the Radius Remote Pilot Radio Software.

SyTech Radius nPoint UAS Diagram - Components.png
The Radius Distribution Service

The Radius Distribution Service (DS) functions as the operating system for the encompassing RoIP network. Built from the Linux kernel and ARM technology,  Radius DS form factors including a (1) Radius DS server node or gateway, (2) a dedicated Linux server, (3) or an instance of the Radius DS software accessible from the cloud. The Radius DS manages all nets, users, and status messages operating throughout the Radius network.

The Radius Client / Remote Radio Software

The Radius Client functions as the graphical user interface for the Radius system. The Radius Client offers easy-to-use features designed for radio-over-IP communications as well as advanced features for multi-operator dispatch and command and control.

The Radius Client features remote radio control for select radio models. The Radius Virtual Control Head (VCH) enables virtual radio control features such as channel selection, zone selection, and other available functions of the radio.


In the video below, the Radius virtual control head is integrated with the Air Avionics AC-1 VHF radio. In this configuration, the VHF radio is installed on the uncrewed aircraft and remotely control over an IP link to the remote pilot. 

The Radius nPoint

The Radius nPoint functions analog-to-digital radio interface gateway installed on the aircraft. The Radius nPoint physically connects to the airborne radio’s auxiliary port, allowing for two-way transmit and receive capabilities. The nPoint runs on 5 volts DC, with a power draw of 300mA - 600mA. Its small size and low power requirements make it ideal for use in UAVs.

The nPoint receives radio audio and digitizes the reception. The nPoint utilizes an onboard Linux processor to compress the audio to 9.6 kbps. Audio is packaged as UDP, reducing bandwidth requirements over the satellite link. The audio is then transported through the aircraft modem, the satellite network, and down to the RADIUS DS and Radius Client. SyTech property methodology insures clear, smooth audio at the operator locations in both transmit and receive from the remote pilot to the aircraft and from ATC to the remote pilot.

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The Radius nPoint offers the ability to communicate via RS-232, RS-485, or USB to the onboard radios, enabling remote radio control capabilities from the Radius Client. The resulting configuration allows the remote pilot to change frequencies as directed by ground control.

The SyTech RADIUS solution provides UAV operators with a means of complying with FAA regulations while communicating via VHF or tactical radios to enable non-line-of-sight range extension. The solution leverages the Iridium Satellite Network, providing global coverage while enabling operators to communicate with their aircraft from anywhere in the world. 

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