COMPONENT MAINTENANCE MANUAL
AVIATION RECORDERS
FA2100CVR
Rev. 15 Page 48
Apr. 14/16
Description and Operation
23–70–04
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dio Reconstructer task is also shutdown to free resources and CPU band-
width.
(b)
The Audio Channelizer task receives the shutdown message, but contin-
ues to process any 8 ms blocks of audio data that may be in its input
queue.
(c)
When it has processed all pending data, the Audio Channelizer zero fills
any remaining partial 36 work channel specific packets. The last packets
are sent to the CVR Executive along with a “shutdown complete” indica-
tion.
(d)
Upon receiving the shutdown complete indicator from the Audio Channe-
lizer task, the CVR executive knows that it has processed the last of the
audio channel packets. Record position indices are then stored in
NVRAM (via the NVRAM manager task). If the “shutdown complete” indi-
cation is not received from the Audio Channelizer task within the pre-
scribed timeout limit, the CVR Executive will proceed with the shutdown
sequence. This prevents an Audio Channelizer anomaly from inhibiting an
orderly storage of pointer indices and other data before the power fail re-
set occurs.
(e)
After the NVRAM values have been updated, the CVR executive enters
an idle loop waiting for power to drop. If the power fail indicator relents,
the CVR executive will perform a re-initialization and re-enter the record
state.
(4)
Data Playback State
Data Playback state is enabled when the SMP Mode Executive task detects a
playback request command from the GSE via the TDM bus. Playback of audio
data is inhibited if the recorder is installed in an aircraft through sensing of the
record bias input signal.
Requests for audio data playback from the GSE are forwarded to the CVR
Executive task. The CVR Executive will calculate the physical memory indices
for the playback start point based on playback positioning commands (rewind,
forward, fast rewind, fast forward) received from the GSE. Audio data output
starts when the “play” command is received. At that point, the CVR Executive
will start to retrieve 36 word packets of channel specific audio data from the ap-
propriate memory partitions. The packets are passed to the Audio Reconstruct-
er task which, in turn, multiplexes the 2 ms. frames of audio data and transmits
it to the GSE over the TDM bus. This process continues until the end of the re-
cording is reached or a stop command is received from the GSE.
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