| 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.
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