4-1
DVW-250/250P
Circuit Description
This unit records and reproduces video and audio signals
on the tape in a digital Betacam format. To reduce an
acoustic noise, this unit decreases the number of drum
revolutions to a half of a broadcast machine and doubles
the recording heads (eight).
Recording System
A video input signal is one of the signals below.
• Composite video signal
• Y/R-Y/B-Y signal
• SDI(D1 format serial digital) video signal
An audio input signal is one of the signals below.
• Analog audio signal (Line audio and camera mic)
• SDI(D1 format serial digital) audio signal
The composite video signal input to the VPR-12 board is
converted from analog to digital, then Y/C-separated using
a composite decoder. The separated Y and C signals are
then multiplexed and sent to the TBC buffer on the DPR-
62 board.
Y, R-Y, and B-Y signals are converted from analog to
digital. After that, the R-Y and B-Y signals are multiplexed
and sent to the TBC buffer on the DPR-62 board together
with the Y signal.
The SDI signal input to the DIF-31 board is parallel-
converted, then separated into video data and audio data.
The video signal is sent to the TBC buffer on the DPR-62
board, and the audio data is sent to the audio processor on
the DPR-62 board.
One of the three video input signals (digital video data)
described above is selected by the TBC buffer on the DPR-
62 board.
For the video data output from the TBC buffer, the setup is
eliminated and the VITC is added. After that, the video
data is compressed to a rate of 1/2 by a bit rate reduction &
ECC encoder, and an outer ECC is added to the video data
for track interleaving.
An input analog audio signal is converted from analog to
digital on the ADA-44 board, then sent to the audio
processor on the DPR-62 board.
For the audio data output from the audio processor, an
outer ECC is added by an ECC encoder for field shuffling.
The video data and audio data are then multiplexed, and
the inner ECC is added. After that, the video data and
audio data are separated to 2-channel parallel REC data.
Using a data rate converter, the 2-channel parallel REC
data is converted into 4-channel serial REC data whose
clock frequency was converted into 1/2. The converted
data is then sent to the drum and recorded.
During cue recording, the signal obtained when the analog
audio signals in channels 1 to 4 were mixed is used as a
cue signal. During cue dubbing, the analog audio signal in
channel 4 is used as a cue signal.
Section 4
Block Diagrams and Circuit Description
