Onboard Computer Main Elements

Figure 1.2 and in more detail figure 4.3 show the embedding of an OBC into the overall spacecraft avionics system. The OBC is connected to the transponders for interfacing with the ground, has bus interfaces connecting it to intelligent spacecraft control units and to the “Remote Interface Unit”, (RIU) – in figure 4.3 called “I/O Board” – and finally the OBC has interfaces to dedicated payload computers or controllers. The RIU couples the OBC to all spacecraft equipment which does not provide a high level data bus interface. The following figures show examples of real OBCs to give an impression on state of the art machines (both ERC32 based). The CryoSat OBC in figure 4.1 – cabled in the test bench – is an engineering model.