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Triggering the Oscilloscope
To use TV triggering
Example exercises The following are exercises to familiarize you with TV triggering.
To trigger on a specific line of video
TV triggering requires greater than 1/2 division of sync amplitude with any
analog channel as the trigger source. Turning the trigger Level knob in TV trigger
does not change the trigger level because the trigger level is automatically set
to the sync pulse tips.
One example of triggering on a specific line of video is looking at the vertical
interval test signals (VITS), which are typically in line 18. Another example is
closed captioning, which is typically in line 21.
1 Press the Trigger More key, then press the TV softkey.
2Press the
Settings softkey, then press the Standard softkey to select the
appropriate TV standard.
3Press the
Mode softkey and select the TV field of the line you want to
trigger on. You can choose
Line:Field1, Line:Field2, or Line:Alternate.
4Press the
Line # softkey and select the number of the line you want to
examine.
When using Generic as the TV standard, you can select a line number to trigger
on when Mode is set to Line:Field1, Line:Field2 and Count:Vertical.
Alternate Triggering
If Line:Alternate is selected, the oscilloscope will alternately trigger on the selected
line number in Field 1 and Field 2. This is a quick way to compare the Field 1 VITS
and Field 2 VITS or to check for the correct insertion of the half line at the end of
Field 1.