Design of an optical communication system for cubesats

Abstract

This Maser Thesis is part of a projectinvestigation from the DISEN group. Within this program, the CubeSat project aims to connect several satellites to improve optical data transmission in the space. This Master Thesis mainly covers the design and simulation of a free-space optical communication system intended for a data transfer of at least 1 Mbit/s. System Requirements inherent to its application on free-space were the starting point to design system power needs. Free-space optical communication demands high power as well as specific precision and speed in a limited board. The high-speed transmitter is composed of a VCSEL whereas the receiver is composed of a PIN photodiode. Up to three different switches have been simulated in MULTISIM software and compared in the following fields: - Frequency response - Minimum noise contribution - Performance with available power source Most of the time spend in this thesis, has been dedicated to obtain knowledge about the free-space optical communication properties. Hundreds of components have been investigated and its datasheets compared according to FSO properties. As the MULTISIM software selected for the simulations is based on PSPICE models of the components, the design of these models has been widely studied. The selected ones have been simulated to ensure the functionality of the circuit. The frequency analysis will determinant to select one of the transistors. In this Master Thesis, the cut-off frequency term will be widely used to describe the bandwidth of each transistor. This thesis has resulted in an optimized emitter and receiver circuits for high-speed FSO.