Video Signal Processing Circuit - Sony HXCU-100 Service Manual

[Video Signal Processing Circuit]

The DPR-300 board has two circuits for the main-line system and the return system. In the main-line
system circuit, the OFDM-modulated signal from the camera is demodulated, and the demodulated signal
is down-converted and processed. Then video signals of each system are transferred to the rear boards. In
the return system circuit, the return video signals from the SY-364 board and the VBS prompter signal
from the rear boards are encoded, OFDM-modulated, and are then sent back to the camera.
In the main-line system circuit, the stream signal demodulated from the signal sent from the transmission
block is separated into video signals, audio signals, command signal, and trunk signal.
. The video signals are sent to the DY-23 board to be decoded to baseband video signals.
. Some audio signals are sent to the SY-364 board to be output to the CCU, and others are embedded in
the SDI output.
. The command signal is sent to the SY-364 board.
. The trunk signal is sent to the rear boards to be output.
The video signals decoded to baseband video signals on the DY-23 board are down-converted, if neces-
sary, by the video signal processing IC according to the output format. The audio signal and sync signal
are mixed with the signal for SDI output by the next-stage IC, and the mixed signal is converted to HD-
SDI or SD-SDI serial signal, and the converted signal is sent to the rear boards.
The analog component output signal HD-YPbPr or SD-Ycd from the video signal processing IC is con-
verted to RGB signals by the converter IC according to the output format. The converted RGB signals are
D/A-converted for each channel and are sent to the rear boards.
The VBS-format SD-Ycd output from the video signal processing IC is converted to VBS signal by the
encoder IC. The converted VBS signal is D/A-converted to WF, PIX, and VBS output signals, and these
signals are sent to the rear boards. This circuit has a function to align the subcarrier component phase with
the reference signal input to the CCU for VBS system output.
In the return system circuit, the return video signal from the SY-364 board is sent to the DY-23 board to
be encoded, and is then sent to the OFDM modulation IC. The VBS prompter signal from the rear boards
is decoded by the VBS decoder IC, and is then sent to the ENC-112 board to be encoded. The encoded
signal is sent to the OFDM modulation IC.
The OFDM modulation IC multiplexes the return/prompter signals, the command signal sent to the cam-
era, and the audio signal for the intercom to generate two-system signals (F7 + F9 and F8 waves),
D/A-converts the multiplexed signal, and then sends it to the transmission circuit.
In addition to these circuits for the main-line and return signal processing systems, the DPR-300 board
contains a character generator for CCU menu output, a WFM stair case signal generator, and an EEPROM
that retains signals for the component/VBS video level adjustment data/cable length determination adjust-
ment data.
ENC-112 Board
This small board located on the DPR-300 board functions as a CODEC of video signals for the prompter.
The ICs on this board have MPEG2 encoding/decoding functions, and the CCU side uses the encoding
function.
DY-23 Board
This small board located on the DPR-300 board functions as a CODEC of main-line video signals and
return video signals.
The ICs on this board have encoding/decoding functions for digital triax transmission. Those for main-
line signals use the decoding function, and those for return video signals uses the encoding function.
2-16 (E)
HXCU-100