The SAS-3 programmable telemetry system

Basic concept, system design and operation principles of the telemetry system developed for the Small Astronomy Satellite-3 (SAS-3) are analyzed. The concept of programmable format selected for the SAS-3 represents an optical combination of the fixed format system of SAS-1 and SAS-2, and the adaptive format concept. The programmable telemetry system permits a very wide range of changes in the data sampling order by a ground control station, depending on the experimental requirements, so that the maximal amount of useful data can be returned from orbit. The programmable system also allows the data format to differ from one spacecraft to another without changing hardware. Attention is given to the command requirements and redundancy of the SAS-3 telemetry system.