How SATCOM is Used for BVLOS Drone Flights

By Ronny Vatelmacher - VP product and Business Development | February 19th, 2024

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Military and civilian UAS (unmanned aerial systems) alike are becoming increasingly reliant on BVLOS (beyond visual line of sight) operations, which allow the aircraft to travel great distances from their operators or base stations. BVLOS flights enable drones to perform more efficiently and effectively, as the operator no longer needs to relocate when their drone travels outside the line of sight, and to cover greater areas and distances in a single flight.

Many VLOS drones use communications and data links that depend on line-of-sight RF (radio frequency) transmissions, requiring a clear unobstructed view between the aircraft and ground control station. Even if an operator is authorized to fly BVLOS, these links may be unsuitable for such purposes, as the range of the link will be limited by the curvature of the Earth as well as other obstacles that may cause blockages in the horizontal direction. While this range can be extended by using a taller antenna, eventually a practical limit will still be reached.

What is SATCOM and how does it work?

One method that is used to circumvent the aforementioned limitation of line-of-sight RF links is SATCOM (satellite communications). SATCOM uses direct transmission between Earth-based devices or stations and strategically-placed satellites, which may be in geostationary orbit, low Earth orbit (LEO), medium Earth orbit (MEO), or high Earth orbit (HEO). Signals are broadcast to a satellite, which then redirects, bonds, and amplifies the strength of the signal and retransmits it to the intended destination.

SATCOM transmission may be one-way, in which uplink and downlink occur between the satellite and different earth receivers, or two-way with a separate uplink and downlink, in which bidirectional communications can be established between a satellite and a single device. SATCOM uses a number of different frequencies, each of which provides different data rates and levels of resilience to environmental factors such as atmospheric conditions.

The benefits of SATCOM for drones

SATCOM can be used to send and receive commands via  UAVs from potentially thousands of miles away, but actual piloting drones is problematic due to the latency in connectivity. In addition to command and control (C&C or C2) signals, satellite networks can also be used to transmit imagery and video captured by the drone, as well as other sensor data.

Depending on the network and the orbits of the satellites, SATCOM can potentially provide coverage almost anywhere on the globe, and with High Earth orbit (HEO) this can even include the polar regions. This makes the technology ideal for drones operating in remote regions, and areas with no existing communication infrastructure or in disaster zones where infrastructure has been destroyed.

Real-world applications of SATCOM

SATCOM is used for a wide variety of both civilian and military drone applications, including:

  • ISR (intelligence, surveillance, and reconnaissance) – gathering critical information that will enhance situational awareness and enable more effective decision-making for military forces
  • Remote drone delivery – SATCOM has been used by drones to deliver critical cargo such as vaccines and medical supplies to islands, rural areas, and other remote regions

Mapping, surveying and environmental monitoring – these use cases may require drones to gather data across vast geographical areas, thus requiring an over-the-horizon communication capability such as SATCOM

The disadvantages of SATCOM

While SATCOM enables BVLOS operations and can enhance capabilities beyond those of standard unlicensed RF datalinks, although due to its latency it is not the perfect solution for all drone applications. UAV SATCOM terminals tend to be bulky and heavy, and can significantly impact the SWaP (size, weight and power) budget of an aircraft, and thus its effective range and flight time. While advances in technology have managed to miniaturize the SATCOM terminal somewhat, the smallest drones will still not be able to take advantage of them. Accessing the highest possible data rates also requires larger terminals and antennas, meaning that applications such as real-time high-definition video streaming can only be carried out by larger UAVs.

SATCOM equipment and services are also expensive. The data costs for short-burst messaging may be viable for small businesses, but the bandwidth required for high-capacity streaming can run into thousands of dollars or more per month, putting it outside the reach of anyone other than large enterprises and governments. In addition, SatCom’s high latency precludes it from becoming a serious provider of connectivity for unmanned flights.  

Multi-link cellular communications – an alternative option for long-range and BVLOS drones

Multi-link cellular communication utilizing 4G and 5G networks provides an alternative solution for long-range and BVLOS drone connectivity.  Like SATCOM, it also allows drones to operate almost anywhere in the world, as long as they are within range of a relevant cell tower.

Cellular services, in particular 5G, provide high-bandwidth and low-latency throughput that is ideal for supporting streaming video and real-time command and control, with far lower data costs than SATCOM. Cellular modems are also inexpensive, lightweight and compact, and can easily fit within the SWaP budget of even the smallest UAV.

For some drone platforms, a combined SATCOM and cellular communications system may be highly suitable for ensuring that a backup is available should the primary communications link go down.

Elsight’s Halo – a leading connectivity solution leveraging multi-link cellular communications

The Elsight Halo is a compact, lightweight and low-power solution that allows drone operators and OEMs to take full advantage of the power of cellular communications. The versatile and carrier-agnostic platform aggregates up to four unique cellular (LTE and 5G) datalinks from multiple providers along with SatComm and RF technologies.

These multiple datalinks can be used to ensure critical redundancy for BVLOS drones passing over large geographical areas and through dynamic communications environments, such as high mountains. Halo’s proprietary algorithms continuously prioritizes all available connections to provide the optimized bond for any moment.

Halo’s state-of-the-art capabilities is its secure cellular bonding technology, which takes advantage of maximum throughput for bandwidth-intensive applications such as real-time video and data streaming.

To find out more about how Halo can enable cost-effective and SWaP-friendly BVLOS operations and how it manages a SatCom link, please get in touch.

 

FAQs

What are the benefits of using SATCOM in drones?

SATCOM allows drones to operate over-the-horizon, extending their effective range and leading to more efficient operations. For military drone operators, it also allows the pilot to be located safely out of harm’s way, far away from the battlefield.

What are some real-world applications of SATCOM in drones?

SATCOM technology has been used to power a wide variety of civilian and military long-range and BVLOS drone missions. These include surveillance and intelligence gathering, environmental monitoring, mapping and surveying, and cargo delivery.

Can SATCOM improve the range and coverage of drone communication?

Not really, although SATCOM provides some significant upgrades to drone operations, the connectivity offered will have too high latency to be reliable. In the connectivity world, high latency is a ‘game-over”..

What are the limitations of using only satellite communications?

SATCOM services are expensive and have high latency and high-power consumption, often prohibitively so for applications that require large amounts of data throughput. They may also be susceptible to atmospheric and weather conditions. A more robust solution could combine SATCOM with an additional capability such as cellular communications.

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