Sony DNW-A220, Руководство по обслуживанию

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6-3
DNW-A220
DNW-A220P
(3) Digital Signal Processing Block (DPR-87 Board) and RF Block (EQ-72 Board
and Drum Assembly)
Recording system
One of the external input video signal (SDI/composite) and SX PB video signal sent from the SDI-23
board is selected using the video data selector on the DPR-87 board. The selected signal is passed through
a pre-filter and SX-encoded
using a bit rate reduction encoder to compress the data rate to approximately 1/10.
The compressed video signal and the REC audio signal sent from the APR-27 board are adjusted in delay
,and multiplexed using an ECC encoder. An error correction code is added after that. In this stage, the
system data, including NT (non-tracking) control information, as well as outer and inner ECC codes is
also added and sent to the EQ-72 board.
The REC signal sent from the DPR-87 board is level-modulated on the EQ-72 board according to the
REC current value and sent through a rotary transformer to the drum as REC data. Moreover, the multi-
plexed select control signals of each head are sent to the drum.
The REC data sent to the drum is recorded on the tape. At the same time, the switching timing for head
and REC current value are controlled by a an MPX decoder,
Playback system
The PB output signals of each head are amplified using a pre-amplifier. After that, the PB RF output
signals of each head are multiplexed based on the decoded head select control signal and sent through a
rotary transformer to the EQ-72 board.
One of the two-channel PB RF signals sent to the EQ-72 board is sent through an amplifier to the DM-
114/114P board as an analog Betacam PB signal. In the other channel, waveform equalization, viterbi
decoding, and inner error correction are performed, and the PB RF signal is sent to the DPR-87 board as a
Betacam SX PB signal.
The Betacam SX PB signal sent from the EQ-72 board is non-tracked and outer-error corrected on the
DPR-87 board. The signal is then separated into a video signal and audio signal. The video signal also
branches to two paths.
One is sent to the video data selector on the DPR-87 board as a REC signal during insert editing. The
other is sent to the VPR-34 board and processed by a video jog processing block. Like the video signal,
the audio signal is also sent to the APR-27 board and processed by an audio jog processing block.
(4) Analog Betacam Playback Block (DM-114/114P and PA-218 Boards)
An analog Betacam PB video signal is processed on the DM-114 board. The RF signals (Y and C signals)
sent from the EQ-72 board are waveform-equalized and FM-demodulated, then converted from analog to
digital. The converted signals are then time-base corrected using field memory for various processings
(dropout compensation, edge noise reduction, etc.), Y/C signal multiplexing,
and setup elimination (for NTSC only) and sent to the VPR-34 board. A longitudinal analog Betacam
audio signal is processed on the PA-218 board. The PB signal sent from the audio head is waveform-
equalized and sent to the AU-249 board.