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Operational Recorders

Two recorders are used for serial recording and dumping of digital voice and PCM data from the OI systems. The recorders normally are controlled by ground command, but they can be commanded by the flight crew through the flight deck display and control panel keyboard or through switches on a recorder panel. Input to the recorders is from the network signal processor, either in the form of 128-kbps PCM data or a 192-kbps composite signal that includes the 128-kbps PCM data and two 32-kbps voice channels. The network signal processor receives the PCM data from the PCMMU and voice signals from the audio control center. In addition, during ascent, operations recorder 1 receives three channels of main engine data at 60 kbps. A single recorder can store and reproduce digital data at many rates.

The operations recorders can be commanded to dump recorded data from one recorder while continuing to record real-time data on the other. The dump data are sent to the FM signal processor for transmission to the ground station through the S-band FM transmitter on the S-band FM return link or to the Ku-band signal processor. When the ground has verified that the received data are valid, the operations recorders can use that track on the tape to record new data.

Recorder functions can be summarized as follows:

Data in, recorder 1

  • Accept three parallel channels of engine data at 60 kbps during ascent.
  • Accept 128 and 192 kbps of interleaved PCM data and voice that serially sequences from track 4 to track 14.
  • Accept real-time data from network signal processor. Recording time is 32 minutes for parallel record and 5.8 hours for serial record on tracks 4 through 14 at a tape speed of 15 inches per second.
  • Data in, recorder 2

    • Accept 128 and 192 kbps of interleaved PCM voice and data that serially sequences from track 1 to track 14.
    • Accept real-time data from network signal processor. Recording time is 7.5 hours at a tape speed of 15 inches per second for serial record on 14 tracks.
    • Data out, recorder 1

      • Play back in-flight engine interface unit data and network signal processor digital data through S-band FM transponder or Ku-band transmitter.
      • Play back in-flight anomaly PCM data for maintenance recording
      • Play back data serially to ground support equipment to T-0 ground support equipment umbilical
      • Data out, recorder 2

        • Play back digital data through S-band FM transponder or Ku-band transmitter in flight.
        • Play back anomaly PCM data in flight for maintenance recording.
        • Play back preflight and postflight data serially to GSE T-0 umbilical.
        • Recorder control

          • Recorders are manually controlled from the mission specialist flight deck aft station display and control panel or uplink and onboard computer keyboard.
          • Recorder speeds of 7.5, 15, 24 and 120 inches per second are provided by hardwire program plug direct command.
          • The tape recorders contain a minimum of 2,400 feet of 0.5-inch by 1-mil magnetic tape. They operate at a tape speed of 24 inches per second in the recording mode and 120 inches per second in the playback mode.


            Curator: Kim Dismukes | Responsible NASA Official: John Ira Petty | Updated: 04/07/2002
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