Kenwood CS-3025, Инструкция по эксплуатации

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APPLICATION. OF
X-Y OPERATION
* Phase Shift Measurement
A method of phase measurement requires calculations based on the Lissajous patterns
obtained using X - Y operations.
Distortion due to non-linear amplification also can be displayed.
A sine w a v e input is applied to the audio circuit being t e s t e d . T h e same sine w a v e input
is applied to the vertical input of the oscilloscope, and the output of the tested circuit is
applied to the horizontal input of the oscilloscope. T h e amount of phase difference be-
t w e e n the t w o signals can be calculated from the resulting w a v e f o r m .
T o make phase measurements, use the following procedure.
1 . Using an audio signal generator with a pure sinusoidal signal, apply a sine w a v e test
signal at the desired test frequency to the audio network being t e s t e d .
2 . S e t the signal generator output for the normal operating level of the circuit being test-
ed. If desired, the circuit's output may be observed on the oscilloscope. If the test cir-
cuit is overdriven, the sine w a v e display on the oscilloscope is clipped and the signal
level must be reduced.
3 . Connect the channel 2 probe to the output of the test circuit.
4 . S e l e c t X - Y operation by rotating the S W E E P T I M E / D I V control c l o c k w i s e to the X - Y
position.
5 . Connect the channel 1 probe to the input of the test circuit.
(The input and output test connections to the vertical and horizontal oscilloscope in-
puts may be reserved.)
6. Adjust the channel 1 and 2 gain controls for a suitable viewing size.
7. S o m e typical results are s h o w n in Fig. 1 6 .
If the t w o signals are in phase, the oscilloscope trace is a straight diagonal line. If the
vertical and horizontal gain are properly adjusted, this line is at a 4 5 ° angle. A 9 0 °
phase sift produces a circular oscilloscope pattern.
Phase shift of less (or more) than 9 0 ° produces an elliptical oscilloscope pattern. T h e
amount of phase shift can be calculated from the oscilloscope trace a s s h o w n in Fig. 1 5 .
Where 0 = phase angle
Fig. 1 5 Phase shift calculation
Fig. 1 6 T y p i c a l phase measurement
oscilloscope displays
28
SINE 4>= —
B
No amplitude distor-
tion, no out of phase
No amplitude distor-
tion, out of phase
Amplitude distortion,
no out of phase
Amplitude distortion,
out of phase
1 8 0 ° out of phase
9 0 ° out of phase