Example 6: Video Signal Trigger - Owon PDS5022S User Manual

User's Manual of OWON Colour Digital Storage Oscilloscope
8. Adjust the VOLTS/DIV and VERTICAL POSITION knobs, optimizing the
wave form.
9. With the elliptical oscillogram method adopted, observe and calculate the phase
difference (see Fig.70).
Based on the expression sinq =A/B or C/D, where, q is the phase difference angle,
and the definitions of A, B, C, and D are shown as the graph above. As a result, the
phase difference angle can be obtained, namely, q =± arcsin (A/B) or ± arcsin (C/D).
If the principal axis of the ellipse is in I and III quadrants, the determined phase
difference angel should be in I and IV quadrants, that is, in the range of (0- π /2) or
(3π / 2- 2π). If the principal axis of the ellipse is in the II and IV quadrants, the
determined phase difference angle is in the II and III quadrants, that is, within the
range of (π / 2 - π) or (π- 3π /2).

Example 6: Video Signal Trigger

Observe the video circuit of a television, apply the video trigger and obtain the stable
video output signal display.
Video Field Trigger for PDS5022S,PDS6042S,PDS6062S,PDS6062T
For the trigger in the video field, carry out operations according to the following
steps:
The signal must be
centered and kept in the
horizontal direction.
Fig.70 Lissajous Graph
80