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A P P L I C A T I O N OF X - Y O P E R A T I O N
CS-1022, 1 0 2 1 , 1 0 1 2
•
Phase Shift Measurement
A method of phase measurement requires calculations bas-
ed 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 t o the audio circuit being
tested. The same sine wave input is applied to the vertical
input of the oscilloscope, and the output of the tested cir-
cuit is applied to the horizontal input of the oscilloscope.
The amount of phase difference between the t w o signals
can be calculated from the resulting waveform.
To make phase measurements, use the following pro-
cedure.
1. Using an audio signal generator w i t h a pure sinusoidal
signal, apply a sine wave test signal at the desired test
frequency to the audio network being tested.
2. Set the signal generator output for the normal operating
level of the circuit being tested. If desired, the circuit's
output may be observed on the oscilloscope. If the test
circuit is overdriven, the sine wave display on the
oscilloscope is clipped and the signal level must be
reduced.
3. Connect the channel 2 probe t o the output of the test
circuit.
4 . Select X-Y operation by placing the TRIG MODE switch
in the X-Y position.
5. Connect the channel 1 probe to the input of the test cir-
cuit.
(The input and output test connections to the vertical
and horizontal oscilloscope inputs may be reserved.)
6. Adjust the channel 1 and 2 gain controls for a suitable
viewing size.
7. Some typical results are shown in Fig. 2 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 ellip-
tical oscilloscope pattern. The amount of phase shift
can be calculated from the oscilloscope trace as shown
in Fig. 2 5 .
Fig. 25 Phase shift calculation
SINE <f> =
-^r
A
Where
phase angle
CS-1020, 1 0 1 0
•
Phase Shift Measurement
Phase measurements may be made w i t h an oscilloscope.
Typical applications are circuits designed to produce a
specific phase shift, and measurement of phase shift
distortion in audio amplifiers or other audio networks.
Distortion due to non-linear amplification is also displayed
in the oscilloscope waveform.
A sine wave input is applied to the audio circuit being
tested. The same sine wave input is applied to the vertical
input of the oscilloscope, and the output of the tested cir-
cuit is applied to the horizontal input of the oscilloscope.
The amount of phase difference between the t w o signals
can be calculated from the resulting waveform.
To make phase measurements, use the following pro-
cedure.
1. Using an audio signal generator w i t h a pure sinusoidal
signal, apply a sine wave test signal at the desired test
frequency to the audio network being tested.
2. Set the signal generator output for the normal operating
level of the circuit being tested. If desired, the circuit's
output may be observed on the oscilloscope. If the test
circuit is overdriven, the sine wave display on the
oscilloscope is clipped and the signal level must be
reduced.
3. Connect an external horizontal input cable from the out-
put of the test circuit to the EXT TRIG INPUT jack of the
oscilloscope.
4. Set the TRIG MODE switch to X-Y position for X-Y
operation.
5. Connect the VERT. INPUT probe to the input of the test
circuit. (The input and output test connections to the
vertical and horizontal oscilloscope
reversed. Use the higher vertical gain of the oscilloscope
for the lower level signal.)
6. Adjust the vertical and horizontal gain controls for a
suitable viewing size.
7. Some typical results are shown in Fig. 2 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 ellip-
tical oscilloscope pattern. The amount of phase shift
can be calculated from the oscilloscope trace as shown
in Fig. 2 5 .
Fig. 25 Phase shift calculation
inputs
may
be
SINE 4,=
~
A
Where < $ > = phase angle
27
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