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~~) INPUT SIGNALS
HORIZONTAL SYNC PERIOD
Horizontal
sync signal
4.6uS
VERTICAL SYNC PERIOD
Vertical
sync signal
4H (0.253mS)
Data display period
46.0uS
Period up to
Data display
video start
period
20H (1.27mS)
288H (18.23mS)
HOW TO PROVIDE THE COMPOSITE VIDEO SIGNAL
hen the output signal from the signal generator is video sync separated, convert it into a composite
sync signal using the circuitry in the figure below.
Horizontal sync signal
Horizontal period 63.3uS (15.80kHz)
Vertical period 316H (20.0mS, 50Hz)
Period up to
vertical sync
4H (0.23mS)
@
@ set the sync signal distortion
(overshoot and under-shoot) to
less than 10%.
@ Set the sync signal to 30% +5%
of the input signal's amplitude.
RO1 150
AAA,
,
ROG 150
Q01 2SC536
(positive polarity)
oO
|os
1/6 SN7406
§
Vertical sync signal
(positive polarity)
1/6 SN7406
Videosignal
(positive polarity)
-
5
~
1/6 SN7406
VV
RO8 68
1/6 SN7406
RO3 330
=f02 330 2
C02 0.
y
1
ROS 470
Wy
MM
RO7 100
R04 150
|
-O
+B 5V
Coupling
capacitor
C01 100u
(sync negative polarity)
Composite video signal
Clu
below will arise
TROUBLE
CAUSE
CAUSE
Picture is too
wide.
Data display period
is
more than 46us.
TROUBLE
Picture extends
too far ver-
tically.
Vertical blanking period
is less than 28H.
Picture is too
narrow.
Data display period is
less than 46us.
Picture tends to
top.
Period up to the vertical
sync signal is more than
4H.
Picture tends to
right.
Value given when front
porch is subtracted from
back porch is more than
3.5uus.
Picture tends to
bottom.
Period up to the vertical
sync signal is less than
4H.
Picture tends to
Value given when front
porch is subtrated from
Horizontal bars
Horizontal sync frequen-
left.
back porch is less than
appear on
cy is no longer 15.80kHz.
picture.
3.5us.
Picture is
= = :
.
J
cram
Vertical blanking period
Picture flows
fg
Vertical sync frequency
ped
/
,
vantieally,
is more than 28H.
vertically.
og|
is no longer 50Hz.
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