Multiprocessor data acquisition system

A VME-based multiprocessor system primarily designed as the data acquisition system for a position-sensitive, driftless, gas proportional scintillation counter for X-ray astronomy is described. The counter is built around a nine-photocathode photomultiplier tube. The system was specified so that an external signal triggers the acquisition of nine analog data channels at a 20-MHz rate, with all channels operating in parallel and synchronized. For each data frame a preprocessing algorithm runs in each processor and is followed by a validation routine in the tenth processor. According to the validation decision data may be discarded or collected by the host VME computer. For this purpose a special parallel architecture was developed in which a digital signal processor is dedicated to each data channel, taking care of the acquisition, the preprocessing, and the validation algorithms. Physically the system consists of a set of VME boards each containing two TMS320C26 DSPs and two 20-MHz data acquisition channels