If one sees a satellite as being a remote sensing platform or as a communication path between two terminals on the Earth, one can appreciate that the spacecraft and its complementary ground infrastructure are essentially electronic devices handling data for the benefit of a ground-based investigator or user. As such, there is a space data-handling system which comprises an onboard and a ground segment. Both segments cover the functions of data collection, data distribution, data processing and storage, data encoding and decoding, timing and synchronisation of events, and data transmission and reception currently forming the well known telemetry data link and the telecommand data link (TTC).