Alignment Control of an Optical Link in a Turbulent Channel for Satellite Communication Systems

November 19, 2021

The use of satellites in communications has revolutionized the transmission of information, allowing to interconnect increasingly distant points. Optical systems began to be explored and their multiple advantages over radio systems have made them an interesting alternative for communications between Earth and space. Optical systems achieve high accuracy by using narrow laser beams. However, when a satellite is in orbit the alignment between terminals becomes extremely challenging, not only because of the narrowness of the beams but also because of the degradation of the signal caused by the propagation in the atmosphere. These problems are magnified when we refer to small satellites, due to their size, weight and power constraints. The objective of this dissertation is to study a closed-loop pointing system that optimizes the alignment between emitter and receiver terminals of an optical communication between a small satellite in low orbit and the Earth, test the system under atmospheric turbulence conditions and perspective the feasibility of a long range link. The implemented pointing system receives the uplink beacon and corrects the position of the downlink signal so that there is alignment. The position control was done using a closed-loop proportional, integral and derivative control system that allows corrections until 3.4 mrad. The system was set up experimentally and tested under turbulent conditions, showing that is possible to improve the link performance.

Authors in the community:

• 

  A

  Ana Carolina Teixeira Borralho

  ist425294

Supervisors of this institution:

• 

  P

  Paulo Sérgio De Brito André

  ist17890

electrical-engineering-electronic-engineering-information-engineering - Electrical engineering, electronic engineering, information engineering

eng - English

Instituto Superior Técnico