• A PC-Based Data Acquisition and Compact Disc Recording System

      Bretthauer, Joy W.; Davis, Rodney A.; NASA/GSFC (International Foundation for Telemetering, 1995-11)
      The Telemetry Data Distribution System (TDDS) solves the need to record, archive, and distribute sounding rocket and satellite data on a compact, user-friendly medium, such as CD-Recordable discs. The TDDS also archives telemetry data on floppy disks, nine-track tapes, and magneto-optical disc cartridges. The PC-based, semi-automated, TDDS digitizes, time stamps, formats, and archives frequency modulated (FM) or pulse code modulated (PCM) telemetry data. An analog tape or a real-time signal may provide the telemetry data source. The TDDS accepts IRIG A, B, G, H, and NASA 36 analog code sources for time stamp data. The output time tag includes time, frame, and subframe status information. Telemetry data may be time stamped based upon a user-specified number of frames, subframes, or words. Once recorded, the TDDS performs data quality testing, formatting, and validation and logs the results automatically. Telemetry data is quality checked to ensure a good analog source track was selected. Raw telemetry data is formatted by dividing the data into records and appending header information. The formatted telemetry data is validated by checking consecutive time tags and subframe identification counter values (if applicable) to identify data drop-outs. After validation, the TDDS archives the formatted data to any of the following media types: CD-Recordable (CD-R) Disc (650 megabytes capacity); nine track tape (180 megabytes capacity); and erasable optical disc (499 megabytes capacity). Additionally, previously archived science data may be re-formatted and archived to a different output media.