Satellite constellations and the broadcast world: a true alternative?

Máximo Morales Céspedes, PhD researcher at the Carlos III University of Madrid, sheds light on the landscape of low-orbit satellite constellations (LEO – Low Earth Orbit) and its possible applications to the common video transmission flows of broadcast workflows.

Los geostationary satellites, that is, the satellites that of all life They have been used to support video broadcasts and thus ensure the availability of a live connection or the transport of signals between broadcast infrastructures, they have been displaced in the last five years by broadcast backpacks. Perhaps it is unnecessary to explain many of the reasons that have led television stations to opt for these alternatives, being lowering costs are summarized in him and in his versatility deployment.

The evolution from 3G to 4G, still waiting for the true 5G, has solved many of the operational problems that were brought about in its initial deployment, such as retransmission capabilities, the resilience of the systems or their ability to alternate between different retransmission points when this equipment is used on the move. However, there are still problems that these solutions have not been able to answer: the stability of the network in situations of high demand (he slicing still remains a promise) or its dependence on the development of the telecommunications network, which makes its use in remote places difficult. Faced with these problems, broadcasters look for solutions (something innate to their nature). Some of them seem almost to have fallen from the sky.

The rise of companies like Starlink they only demonstrate an aerospace race around the low orbit satellite constellations. And many television stations have pinned their hopes on solving connectivity and availability challenges on these systems, which are quick to deploy and easy to access. However, are they a real, reliable and profitable alternative for the daily lives of broadcasters? Máximo Morales, PhD researcher at the Carlos III University of Madrid, debunks myths about the umpteenth revolutionary technology for the audiovisual world.

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The low orbit satellite versus the stationary satellite

“When we talk about low orbit satellites we have to see where we come from,” explains Morales, pointing out the important conceptual and basic differences between geostationary satellites and low orbit satellites.

The first alternative, the one that has been with us for the longest time, is located at an approximate height of 36.000 km and always found fixed at the same point (or rather, it is made to rotate at the same speed as the earth). However, low orbit satellites are located at an altitude of between 500 and 1200 kilometers high and they are in continuous scrollingSpecifically, a Starlink satellite, located 540 kilometers high, orbits the Earth every 93 minutes.

"The concept of a constellation can be explained by dividing the earth into planes. Instead of having one very large satellite, you have many very small satellites what is they move very fast and that cover a certain area”.

Hence the need to build the so-called “satellite constellations”, a solution that will help preserve a broadcast lasting several minutes by exchanging the availability of the different satellites: “The concept of constellation can be explained by dividing the earth into planes. Instead of having one very large satellite, you have many very small satellites that move very quickly and cover a certain area.”

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Availability and latency

These data, inherent to the nature of each of the alternatives, determine their applications and define their advantages and disadvantages. For example, where a geostationary satellite can always ensure its availability in its coverage area, the orbit satellite user low will depend on the location of the satellite constellation and its movement, forcing what in the world of telecommunications is known as the “handover between satellites”: “In these cases, you connect to a satellite and you have to be ready to connect to the one that is coming or to possible overlaps.”

Other critical issue To better understand the nature of each of the satellite alternatives under study is the question of latency. The distance at which the signals have to be downloaded makes the geostationary satellite offer a 125ms average latency, while the low orbit satellite allows us to talk about a latency of 2 o 5ms, “which allows it to compete directly with today's 5G systems,” says Morales.

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Low optical satellites: similar problems to 5G networks

The conceptual bases previously described help to understand the main differences that continue to exist today between “traditional” satellites and LEO: availability y service reliability.

For Morales, the use of low orbit satellites is similar to “entering a network of mobile connectivity". The user who subscribes to one of these services (with a cost of €100 per month as a flat rate from Starlink plus the cost of the receiving device) You are not guaranteed access to the network, given that the connection to a satellite constellation may be requested by other agents. As with 4G and 5G telephone networks, it all depends on the concurrence. If multiple broadcasters connect from the same geographic point to the same constellation to provide the same coverage, it is very possible that network availability will falter.

If multiple broadcasters They connect from the same geographical point to the same constellation to provide the same coverage, it is very possible that the availability of the red se tambalee.

Furthermore, Morales points out that until broadcast solution providers offer solutions that are fully integrated with their video encoding systems, they will be necessary patches to solve additional problems: "The speed will be very variable, so even the video encoder can vary. To solve this, it will be necessary to design a buffer that stores the video packets, since there may be moments of failure when the transfer of the signal from one satellite to another does not occur in the most appropriate way."

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LEO: alternative for specific cases

For all these reasons, for Morales it doesn't make any sense opt today for a connection with low orbit satellite constellations for live video connections.

Of course, as long as there are alternatives such as talk about 5G or the connection option via fiber to the public internet. If this is not the case, low orbit satellites can offer solutions to transmit content from those locations where mobile connectivity is not available, whether rural areas, jungles or Antarctica itself. With the previously mentioned difficulties, it will be possible to transmit live video with high resolutions and frame rates.

Likewise, these systems could replace and reduce the cost of sending audiovisual material (dailies) on shoots in which producers or production teams may need immediate access to pieces in remote locations: “If we want to send a video package from Antarctica to Los Angeles, and we don't care if that package arrives in 30 minutes or 35, these systems can be an alternative.”

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A race to improve low orbit satellites

The nanosatellites that make up the orbit constellations base their nature on the construction standard CubeSat: a square of 10x10x10 centimeters that, when combined with other CubeSat units, allows aerospace equipment to be formed with different functions.

With “super-standardized” manufacturing and with releases that can already be managed independently by private capital, the great challenge of the industry is to improve technological capabilities of these teams. They will not solve the problems of their nature, such as availability or their rapid movement around the Earth's orbit, but many of their processes will be improved: "There is a race to introduce all the electronics necessary for different processes in a CubeSat. But it is complicated, since you have to think about many things: since it is such a small piece, you cannot put very large solar panels; since you are in space, it is very difficult to dissipate heat, so very efficient solutions must be found...".

“Low orbit satellites, having a small life time, can integrate different signal processing tools, which is something very attractive.”

Unlike geostationary satellites, low-optical satellites also have a differentiating element that marks the technological race that surrounds them: their limited life time. Given their proximity to the Earth's atmosphere, it is "inevitable" that within "three to seven years" they will fall. “It is not a drama, but something totally normal,” says Morales, who also sees this fact as an chance so that, in video applications, these devices take advantage of the latest video coding technologies: "The geostationary satellites launched in the 90s are transparent; in some way, they are oblivious to the passage of time and can continue to receive signals and transport them efficiently. Low orbit satellites, having a short lifespan, can integrate different signal processing tools, which is something very attractive."

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The convergence between mobile networks and satellites

In the future, there is a good chance that an on-air video stream run from a broadcast dongle feeds into the growing low orbit satellite industry without the user himself being aware of the use of this technology.

As Morales explains: "The latest versions of 5G or the first sketches of 6G do not consider satellite communications as something foreign. On the contrary, Low orbit satellite communications are going to be integrated into mobile communication systems. In this way, possibly in 2030 or before, we can be unaware of whether our mobile phone is connecting through a low orbit satellite, WiFi network or mobile communications system.”

The arrival of systems low orbit satellites to the offers of telecommunications companies is already underway: operators around the world are announcing agreements with companies specialized in this field or enhancing their aerospace capabilities in light of the promises of this new window, especially with regard to providing coverage in remote areas, the IoT world or, of course, in broadcast applications.

A report by Sergio Julián Gómez