14.1 Payload Definition

A communication satellite payload is the system on board the satellite which provides the link for the communications signal path. Traditionally, this link was between two ground stations but present-day payloads now provide not only for this link but also can provide interconnectivity for a large number of mobile users directly to each other or via the ground stations.

Payloads are providing this extra functionality to meet the needs of more mobile populations, rapidly changing traffic demands and variable operational scenarios. To do so they have become more complex and more powerful, which has become possible through advances in technology, reducing the mass and power consumption of the electronics equipment for a given level of functionality or performance.

14.2 Payload Function

The primary and most fundamental functions of the payload are to receive and filter the uplink signals and provide frequency conversion and amplification of the signals for retransmission, thus satisfying the requirements for the uplink G/ T, the downlink EIRP and the system frequency planning. In addition, the payload must provide minimum C/ N ₀ degradation, variability of the high-gain amplification, channelisation for efficient, linear amplification and processing and high reliability in functionality. With modern payloads flexibility is provided using digital and/or analogue processing and connectivity for routing traffic between beams.