Design and construction of a modem for satellite use

[摘要] ENGLISH ABSTRACT: In this thesis the design and testing of the baseband components of a modemintended for use as a telemetry and control link for a low earth orbit satellite ispresented. This includes parts of the physical layer as well as a basic data-linklayer. Binary phase-shift keying (BPSK) is used as the modulation schemeand is realised by making use of software defined radio on a standard x86computer with digital to analogue and analogue to digital converters that usea universal serial bus (USB) connection. The data-link layer makes use of abasic framing scheme and provides bit synchronisation, an automatic repeatrequest (ARQ) system and Bose Chaudhuri Hocquenghem (BCH) forward errorcorrection (FEC). The ARQ system ensures that data is delivered reliably andthe FEC improves the system's performance in noisy conditions. A prototypesystem was developed to test the performance of the individual layers as wellas the system as a whole. For testing purposes the Linux Internet Protocol (IP)stack is used as higher network layers. Radio frequency hardware developed byVerschaeve[1]modulates the signal away from baseband, transmits it over theair and receives it.

[发布机构] Stellenbosch University