Learning Event 2:
DESCRIBE HOW THE VIDEO SIGNAL IS PROCESSED FROM THE LENS TO THE FINAL PICTURE
Pulse processing: All pulses applied to the camera control unit are
buffered by the input buffer board (A26).
Composite sync from the buffer
board is sent to encoder YIQ matrix board (A23), the bar generator board
(A24), and the sync delay board (A25). Delayed composite sync from (A25),
is used on the encoder control module (A32) and the viewfinder processor
a. Composite blanking from the input buffer board is applied to the YIQ
matrix board, the bar generator board, the picture and waveform monitor
board (A4), and to the three video II boards (A7, A8, A9).
b. Vertical drive from the input buffer board goes directly to the
timing generator and pulse advance board (A21).
On the timing board, an
astable multivibrator is locked to the vertical drive.
The output of the
multivibrator is converted to a vertical timing pulse and sent to the camera
head. Vertical timing pulses go to the camera head as negative pulses, and
horizontal timing pulses are sent to the camera head as positive pulses on
c. Horizontal drive from the input buffer board goes to the enhancer
modulator board (A19), where it is used to generate timing pulses in the
The horizontal drive pulses also go to the timing
generator board (A21), where they are used to set the frequency of the
The output of the latter is used to produce the
internal horizontal blanking and the advanced horizontal timing pulses for
the camera head.
Should horizontal drive to the CCU be intercepted, the
astable multivibrator would continue to supply horizontal timing pulses to
the camera head.
d. Horizontal timing pulses to the camera head are automatically
advanced to compensate for variations in camera cable length. This is done
by comparing the pseudo sync returning from the camera head, to the output
of the horizontal astable multivibrator.
The drive to the camera head is
adjusted automatically so that the video returning from the camera head is
e. The horizontal blanking from the timing generator board is used on
the shading generator board and the sync stripper board.
generates the horizontal pulses used throughout the CCU.-These are: The
horizontal clamp pulse, that is used on video board I and II, the white
pulse is added to the video on the video I board and the white pulse sample
on the video II board. The latter two pulses are used in the video AGC.
In the camera head the positive horizontal timing pulses and the
negative vertical pulses from the CCU are separated on the electrode
a. The vertical drive signal is then sent directly to the master sweep
board and the individual yoke drivers for the cathode blanking.