The Design and Planning of Feeder Links to Broadcasting Satellites

A feeder link is the portion of a broadcasting-satellite system which provides the connection from the earth to the broadcasting satellite. Quality objectives for feeder links are normally well above the corresponding objectives for downlinks. The parameters which affect signal quality are examined. It is shown that the greatest control over the
C/N
ratio lies with the selection of suitable values for the diameter of the feeder link transmit antenna and the power of its associated transmitter. Three mechanisms are available to combat interference between feeder links: discrimination resulting from the feeder link transmit antenna pattern, discrimination derived from the satellite receive antenna pattern, and discrimination due to the use of cross-polarized signals. The use of these mechanisms to create a workable feeder link plan is developed in the paper. There are a number of desirable objectives that can be established for a feeder link plan in addition to the obvious need to meet signal quality (
C/N
) and interference (
C/I
) requirements. A realizable set of objectives is presented along with the approaches used at the ITU Region 2 planning conference to create a satisfactory plan. The technical parameters which must be agreed on in order to develop a feeder link plan are summarized, and the values chosen for the Region 2 plan are presented.