Operation
Video Triggering
The available Television/Video
(TV)
enhancement adds TV LINES. FLD1, and FLD2
Coupling to the A-Trigger. See Appendix A to change the line-number format and the
sync polarity automatically selected when you select TV triggering.
To trigger at the video line rate:
1.
Select a composite video signal as the trigger source.
2.
Select LINES coupling.
3. Set SLOPE to the polarity of the sync.
To trigger at a specific video line:
1.
Select a composite video signal as the trigger source.
2.
Select
FLD1.
FLD2, or ALT coupling.
3. Set SLOPE to the polarity of the sync.
4.
Turn FLD LINE # (A) to the desired line number.
When you increment or decrement the line number outside the range of the
selected
field,
the other field is automatically selected.
With ALT field coupling, the line number is referred to the beginning of both fields.
The trigger level can be adjusted to vary the actual sync trigger point. This can be
useful when triggering on noisy video signals. INIT@50% resets the trigger point to
mid-range.
To compare two video signals with the same format that are not perfectly
synchronized, such as from a camera and a VCR or from the input and output of a time
base corrector:
1.
Display the signals on CH 1 and CH 2, with Alt Vertical mode.
2.
Select VERT Trigger Source, and ALT field trigger coupling.
3. The CH 1 display triggers on field 1 and the CH 2 display triggers on field 2.
TV Lines trigger coupling with multiple vertical channels, Alt Vertical mode, and Vert
Trigger source produce unpredictable results.
A "A" symbol with the line number display shows when the A/FLD LINE # control
can change the line number. If AV, At. or 1/At is on, press a trigger Coupling button to
redirect the control to line number selection. Press AV or At to redirect the control to
cursor or delay adjustment. The first push redirects the control. A second push will
change the A function or trigger coupling.
2465B/2455B/2445B Operators
2-9
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