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CH4.
(4) Push the Autoset button, with the oscilloscope turning on the signals of
the two channels and displaying them in the screen.
(5) Push CH1 button to select CH1, turn the Vertical Scale knob, and then
push CH2 button to select CH2, turn the Vertical Scale knob, making the
amplitudes of two signals equal in the rough.
(6) Push the Display button and recall the Display menu.
(7) Select XY Mode in the bottom menu. Select Enable as ON in the right
menu. The oscilloscope will display the input and terminal characteristics
of the network in the Lissajous graph form.
(8) Turn the Vertical Scale and Vertical Position knobs, optimizing the
waveform.
(9) With the elliptical oscillogram method adopted, observe and calculate the
phase difference (see Figure 8-6).
Based on the expression sin (q) =A/B or C/D, thereinto, 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 the I and
III quadrants, the determined phase difference angel should be in the 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
8.Demonstration
The signal must be
centered and kept in the
horizontal direction.
Figure 8-6 Lissajous Graph
127
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