Satellite Communications Payload and System

Chapter 9

Processing Payload

9.1 Introduction

There are fewer processing payloads than nonprocessing, but the number is increasing as advancing technology allows the payload's mission to become more complex. A processing payload is a payload that has flexibility in most or all of the following: bandwidth allocation, gain, uplink-to-downlink channel mapping, channel-to-beam assignment, and power allocation. Some processing payloads do this with all-analog hardware but most have a digital processor. In terms of how deeply the payload processes the signal, there are two kinds of processing payloads, regenerative and nonregenerative, where the former performs demodulation and remodulation.

This chapter describes the processing payloads currently (2010) on orbit or about to be launched for which the author could find sufficient information. The payloads provide a service and do not simply demonstrate a possible future service. The list of such satellites changes about once a year as companies start up, stop a service, or go out of business.

There are a few reasons why a communications satellite may have a processing payload, among which are the following:

• Infeasibility of performing the quantity of desired processing with traditional hardware
• Accommodation of daily variation in traffic patterns
• Accommodation of long-term traffic changes
• Accommodation of satellite mission change, for example, orbital slot change
• Provision of direct user-to-user connectivity.

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