On the design and implementation of a dependable space instrument

The Digital Wave Processor, DWP, is an example of a dependable distributed system which has been built and will be flown on the ESA/NASA Cluster satellites. Pre-flight testing of the DWP instruments is nearly complete and the results of this programme of testing are described. Much of the fault-tolerant behaviour of DWP has been tested and found to function as expected. Of the problems which have been found the majority are attributed to the initial definition of hardware and software interfaces. Various small hardware limitations and problems have been experienced. These have generally been overcome without there being any impact on the fault-tolerant design, but they have consumed a considerable amount of engineering effort. >