Satellite communication system.

摘要

In a satellite communication system a ground station transmits an information carrying plane polarised signal to the satellite where it is broadcast to a number of individual receivers on the earth. The effect of the earth's atmosphere partially de-polarises the plane polarised signal and to provide compensation for this effect, the earth station transmits simultaneously with the information carrying signal an additional plane polarised signal, which is polarised at right angles to the first signal so as to provide forward correction for the de-polarising effect. The additional signal is arranged to cancel the cross-polar components of the de-polarised signal produced within the atmosphere. A number of methods are described for determining the properties of the additional signal which are necessary to achieve compensation.