Flight and ground packet telemetry systems activities at NASA's Goddard Space Flight Center

NASA's Goddard Space Flight Center (GSFC) has the responsibility for the telemetry ground data processing for two current spacecraft which use packet telemetry. These spacecraft are the Hubble Space Telescope (HST) and the Gamma Ray Observatory (GRO). GSFC has designed and built two ground systems to meet this responsibility. The first is the HST DATA Capture Facility (DCF), which has now completed its integration and test phase and is supporting spacecraft and data flow tests. The second is the Packet Processor System (Pacor). This system became operational in July 1987. These systems are known generally as Level Zero Processors. Level Zero Processors ingest telemetry composite bit streams, output selected user specific data in real time, and in a batch mode perform all necessary processing to produce individual user data files which are, within the limits of the quality of the received data, contiguous, complete, ordered and nonredundant.