Optical inter-satellite links are best tech for Galileo

Optical inter-satellite links (ISL) are the best technology for the next generation of the Galileo Navigation System, a TDE activity (T617-501MM) has shown.

The 2nd generation of the European GNSS “Galileo“, which will be launched around 2022, considers the use of both radio-frequency and optical ISLs for ranging and low- band width communications.

First the team, from Tesat-Spacecom in Germany, issued the design adoptions existing laser communication terminals would need to meet the Galileo requirements. Secondly, they demonstrated that the ranging and communication of the different ISLs could work in parallel, while keeping the key requirements for accuracy and low-bit rate.

They found that the optical inter-satellite links have a proven maturity after being used on the Copernicus Sentinels and the European Data Relay System (EDRS), and so can deliver several benefits for the operator and the end users. Its high technology readiness level means only a few adaptations would be required for the Galileo requirements.  Compared to Radiofrequency ISL’s, the optical inter-satellite links also had the advantage of a much higher data rate, no ITU (International Telecommunication Union) frequency regulation, bi-directional communication and were more robust against interference and signal jamming.

Next, the team plans a demonstration and verification of the required link time slots in a laboratory and the preparation of a demonstration flight on board of a Galileo 2nd Generation spacecraft in 2021.