Specifications

To trigger on odd or even fields

To check the envelope of your video signals, or to measure worst 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.

Select the TV display, TV as the trigger mode, and the appropriate TV

standard as described in the section, "To autoscale on a video signal."

Press

Slope/Glitch

in the

TRIGGER

section of the front panel,

then press the

and

TV Menu

softkeys. Press

Field 1

Field 2

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.

Triggering on Color Field 1 Alternating with Color Field 3

Figure 6-5

Using Option 005 Enhanced TV/Video Trigger (HP 54645A)

To trigger on odd or even fields

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