Telemetry requires only soft realtime, i.e. receiving data at a fixed high rate without loss . These data must be processed in time and delivered to several different applications. The requirement for being real time is weak, as seen by human eye. Therefore standard LINUX is used with a special driver. The driver uses a SBS-4422 decommutation board and delivers data blocks in real time into user-space using cyclic buffer and DMA. The associated application is forced into RT-scheduling (SCHED_FIFO) and uses a standard read to synchronize and to get the buffer pointer. Measurements show that at actual data rates the rt-jitter stays in the range of 1 ms, with some exceptions, which are covered by the ring buffer. At the actual data rates (512 words every 2 ms) no data are lost, even if the remaining system is heavily loaded.

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