Composite Noise Temperature at Low Earth Orbiting Satellite Ground Station

Noise introduces a fundamental limit on the performance of any communication system. Satellite communication systems are particularly susceptible to noise because of their inherent low received power. During the link budget calculations, noises of the equipment and line loss have to be considered. An alternative, but equivalent way of expressing the noisiness of the equipment and line loss is through noise temperature. The noise temperature which represents noise of all components in satellite receiving system chain is called composite noise temperature. Thus, on this paper the methodology applied for composite noise temperature calculations for satellite links is presented. In order to illustrate these calculations, data of Vienna ground station within MOST project are applied. The project MOST (microvariability and oscillations of stars) is a Canadian micro satellite space telescope mission. The project MOST consists of a low earth orbiting (LEO) satellite and three ground stations, one of them in Vienna. The Vienna ground station system was set up at the Institute for Astronomy of the University of Vienna in cooperation with the Institute of Communications and Radio-Frequency Engineering of the Vienna University of Technology. The satellite link operates on 2 GHz band