Guide to Satellite Communications for Drones

Satellite communications are becoming increasingly important for professional drones as operators look to fly aircraft over longer distances, beyond terrestrial communications coverage and across remote environments. While most drones traditionally communicate with their ground station through direct radio links, cellular networks or Wi-Fi, satellite connectivity can extend communications into areas where conventional infrastructure is unavailable. For long-range Beyond Visual Line of Sight (BVLOS) operations, offshore inspection, maritime surveillance, environmental monitoring, emergency response, remote infrastructure inspection and logistics, this can be particularly valuable. A drone operating hundreds of kilometres from populated areas cannot always rely on 4G, 5G or terrestrial radio infrastructure. Satellite communications can provide another communications pathway. However, satellite connectivity is not simply a replacement for a normal drone radio. Bandwidth, latency, antenna size, power consumption, satellite visibility, service coverage and operating cost all influence what can realistically be transmitted. Some systems may only exchange small telemetry messages, while more capable satellite links can support substantially larger amounts of data. As satellite networks expand and terminals become smaller, satellite communications are likely to become an increasingly important component of long-range and highly autonomous drone operations. ## **What Are Satellite Communications for Drones?** Satellite communications, often shortened to SATCOM, allow a drone or its supporting ground infrastructure to exchange information through satellites rather than relying exclusively on a direct terrestrial connection. A drone equipped with an appropriate satellite terminal can transmit information to a satellite overhead. The satellite network then routes that information towards another satellite, a gateway or terrestrial network, depending on the architecture. Information travelling in the opposite direction can provide command, mission updates or other data to the aircraft. The result is the possibility of maintaining communications far beyond the normal range of a conventional ground-based radio. ## **Why Do Drones Need Satellite Communications?** Traditional drone communication systems work extremely well for many operations, but they have geographic limitations. A direct radio link eventually loses coverage as the aircraft travels farther from the ground station, while cellular connectivity depends on terrestrial network infrastructure. Large parts of the world’s oceans, deserts, mountains, forests and sparsely populated regions have limited or no cellular coverage. Infrastructure inspection can also follow pipelines, transmission lines and other assets through these environments. Satellite connectivity provides another option because the communications infrastructure is located above the Earth rather than entirely on the ground. This can allow drones to operate across significantly larger geographic areas. ## **Command and Control** One of the most important drone communication requirements is Command and Control, commonly abbreviated C2. The C2 connection allows information to pass between the aircraft and the system responsible for supervising or controlling the mission. Depending on the aircraft, this can include flight commands, mission updates, aircraft status and safety information. For BVLOS operations, the reliability and performance of the C2 architecture can become a major part of the overall operational safety case. Satellite connectivity may provide the primary C2 pathway in some systems or operate as a backup to another communications network. ## **Telemetry** Telemetry is generally much less bandwidth-intensive than high-resolution video. A drone may transmit position, altitude, speed, heading, battery status, propulsion information, GNSS quality and other aircraft-health information using relatively small amounts of data. This makes telemetry particularly suitable for lower-bandwidth satellite services. Even where continuous video transmission is impractical, satellite connectivity may allow an operations centre to monitor the condition and location of a remote aircraft. ## **Payload Data** Payload data creates a different challenge. High-resolution cameras, LiDAR systems, hyperspectral sensors and other advanced payloads can generate very large datasets. Sending all of this information through a satellite connection may be unnecessary, expensive or technically impractical. Many professional systems therefore process or store payload data onboard the aircraft and transmit only the information required immediately. ## **Satellite Video Transmission** Live video requires significantly more bandwidth than basic telemetry. The required bandwidth depends on resolution, frame rate, compression and image complexity. Satellite networks capable of providing higher data rates can potentially support live drone video, but bandwidth availability, antenna performance and operating costs need to be considered. For some missions, sending lower-resolution situational-awareness video while storing the full-resolution footage onboard provides a better compromise. ## **Onboard Data Storage** Satellite-connected drones will often continue storing the original sensor data onboard. For example, a mapping aircraft may collect hundreds of gigabytes of imagery or LiDAR data during a mission. Sending the complete dataset through a satellite network would often be unnecessary. The aircraft can instead transmit health information, mission status and selected results while storing the primary dataset locally. Once the aircraft lands, the full dataset can be transferred through a much faster local connection. ## **Edge Computing** Edge computing is particularly valuable for satellite-connected drones because it reduces the amount of information that needs to leave the aircraft. Instead of continuously streaming every camera frame, an onboard computer can analyse the video locally. If the AI detects a person, vehicle, fire, damaged component or another relevant event, the system can transmit only the result and selected imagery. This can dramatically reduce satellite bandwidth requirements. ## **AI and Satellite Communications** Artificial intelligence can make limited communications bandwidth much more useful. Imagine a drone monitoring a remote pipeline. Instead of transmitting hours of continuous high-resolution video, onboard AI could analyse the imagery and identify possible leaks, vehicles, people or damaged infrastructure. The aircraft might then transmit an alert containing the coordinates, detection type, confidence level and a compressed image. This changes the communications requirement from constant high-bandwidth streaming to intelligent event reporting. ## **Geostationary Satellites** Geostationary satellites operate at approximately 35,786 kilometres above the equator and appear relatively stationary from a position on Earth. This makes them useful for communications because antennas can remain directed towards approximately the same point in the sky. However, the enormous distance creates noticeable communications latency. Terminals and antennas can also be challenging to integrate into smaller drones. ## **GEO Satellite Latency** Because radio signals need to travel tens of thousands of kilometres to a geostationary satellite and back, latency is significantly higher than with terrestrial communications. For basic telemetry or mission updates, this may be acceptable. For highly interactive manual control, additional latency requires much more careful system design. Autonomous aircraft can reduce this dependency by making immediate flight-control decisions onboard rather than waiting for instructions from a remote operator. ## **Low Earth Orbit Satellites** Low Earth Orbit satellites, commonly called LEO satellites, operate much closer to Earth