Konstruktion och analys av trådlös laserbaserad kommunikationsänk

Abstract

As more and more services are competing for bandwidth, the space in the radio frequency spectrum gets smaller and smaller. One part of the solution to this potentially big problem is to use optical signals instead. Optical communication through fiber optics is a well researched area while wireless optical communication ha limited implementation. In this report, the construction and development of a wireless optical communications link between two computers is presented. The purpose of the link is to improve the basis of future development of wireless optical communication. The end product has the ability to transmit data over 30 m, at 15 kBit/s with a Bit Error Rate under 3 10 6. Data has also successfully been transmitted at higher bitrates, up to 17 kBit/s while experiencing more error bits. The reason for not sending data at higher bitrates is frequency limitations induced in the available components. This has been done using a link based on a sender where data is encoded in the light from a laser diode and a receiver where this light has been read and decoded. To be able to do this, electrical circuits, optics and software has been created. The link has then been analyzed and evaluated with regard to its weaknesses, strengths as well as possibilities for further development