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15! V I D E O S I G N A L O B S E R V A T I O N
The T V FRAME/LINE switch permits selection of vertical or
horizontal sync pulse for sweep triggering when viewing
composite video waveforms. In the LINE position, horizon-
tal sync pulses are selected as triggers to permit viewing of
horizontal line of video. In the FRAME position, vertical
sync pulses are selected as triggers to permit viewing of
vertical fields and frames of video. When observing the
video waveforms, stable display is obtained on the screen
regardless the TRIG LEVEL (Q) control.
At most points of measurement, a composite video signal
is of the (—) polarity, that is, the sync pulses are negative
and the video is positive. In this case, use " - " SLOPE.
If the waveform is taken at a circuit point where the video
waveform is inverted, the sync pulses are positive and the
video is negative. In this case, use " + " SLOPE.
(6) S I N G L E S W E E P O P E R A T I O N
This mode
of
display is useful for
synchronous or one time events.
1 8
Procedure:
1. Set the A TRIG MODE (§) to either AUTO or NORM.
2. Set A TRIG MODE to RESET -
3. After the above set-up is completed the scope is ready
r — CAUTION:
looking at non-
Apply a signal of approximately the same amplitude and
frequency as the signal that is to be observed as the trig-
ger signal and set the trigger level.
indicator LED lights to indicate the reset condition. This
LED goes out when the A sweep period is completed.
to operate in the SINGLE sweep mode of operation after
resetting the instrument using the RESET switch. Input
of the trigger signal results in one and only one sweep
and READY indicator LED goes out.
With the HORIZ MODE set to ALT the simultaneous
observation of the A sweep and B sweep waveforms
at SINGLE sweep mode is not possible. Also for
DUAL or TRI operation simultaneous observation is
not possible using ALT mode. Set the unit to the
CHOP mode in this case.
observe that the READY
,
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