R&D activities in the field of laser telecommunication.
The operation of each device in space, including Earth observation satellites, such as the ScanSAT nanosatellite (link) we are designing, requires data to be transmitted to the receiving stations. How to quickly send gigabytes of information? What if this data is sensitive and there is a need to secure the entire communication process? These and other problems are solved by laser telecommunication.
Laser telecommunication works in the same way as any other which uses an optical fiber – there is also a transmitter and receiver in it. Photons carrying information do not travel in the closed space of optical fiber, but reach the receiving station through the atmosphere.
Traditional radio communication is carried out by appropriate modulation of an electromagnetic wave propagating in every direction and ultimately covering a very large area of the Earth. Laser communication works similarly to fiber-optic communication – information is carried out from point A to point B. The photons in the optical fiber only travel to the target point at the end of the medium (optical fiber) – that is to the receiver. In the space applications, a laser beam uses the atmosphere as a medium, but a properly prepared module for laser communication is able to send a beam to a specific, relatively small point on the surface of Earth.
Sending information in a conventional way – by radio communication – implicates a number of problems. Data is sent using a specific frequency, assigned to one transmitter only through appropriate regulations of the International Telecommunications Union. This means that over time the number of possible frequencies is decreasing. This forces the broadcast of information in other bands, so far reserved, for example, for military purposes. This entails the need to expand the network of ground stations and continuously progressing R&D process. Radio telecommunications, used in government and military applications, must be encrypted to avoid eavesdropping by other ground stations. In addition, it is not able to provide adequate data rate without compromises such as increasing transmission power, larger antenna diameter or ensuring adequate data processing onboard of the satellite.
Laser telecommunication solves these problems. There is no need to regulate the legal matters of the process of information exchange due to the fact that the laser beam can be seen only from a specific place on the Earth. This enables a secure and unique way of transferring the information, in which eavesdropping is only possible when somebody would be physically next to the receiver. Due to the very high energy concentration the transmission power needed is much lower than in conventional telecommunication. The biggest advantage of laser telecommunication is neither its security nor the lack of regulations needed, but a enormous bandwidth. It is possible to achieve even gigabits per second – these values are much larger than those used in conventional radio telecommunication in the X band (e.g. Sentinel satellites reach only around 500 Mbit/s) or others.
Scanway as a part of the design of the ScanSAT nanosatellite (link) tested a laser communication system, composed of COTS modules adapted to the specific needs of the application. System during field tests achieved bandwidth of 919 Mbit/s. It was not the final system neither it was dedicated to the space applications, but rather a first iteration of the result of R&D process. Such activities, conducted both independently and with partners, are to lead to the creation of a standardized laser telecommunication module, intended for integration in various applications – from military vehicles and strategic infrastructure, through drones, to space applications.
Currently Scanway is working to use the laser telecommunication onboard of the ScanSAT satellite. Placing a laser transmitter in such a small satellite, whose main task is Earth observation, is a novelty on a global scale.
It is worth noting that laser communication systems, due to their bandwidth and the lack of eavesdropping capabilities, are ideal solution for military and state security applications. Also in such directions Scanway develops its competences and products.
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