Agilent Technologies 6000 Series To trigger on odd or even fields

196 6000 Series Oscilloscope User’s Guide
4 Triggering the Oscilloscope
To trigger on odd or even fields
To check the en velope of your video s ignal s, or t o measu re wors t
case distortion, trigger on the odd or even fields. When Field 1
is selected, the oscilloscope triggers on color fields 1 or 3. When
Field 2 is selected, the oscilloscope triggers on color fields 2 or
4.
1Press 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 Field1 or Field2.
The trigger circuits look for the position of the start of Vertical
Sync to determine the field. But this definition of field does not
take into consideration the phase of the reference subcarrier.
When Field 1 is selected, the trigger system will find any field
where the vertical sync starts on Line 4. In the case of NTSC
video, the oscilloscope will trigger on color field 1 alternating
with color field 3 (see the following figure). This setup can be
used to measure the envelope of the reference burst.