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• Period
Setting the relative sweep coefficient with respect to a re-
ference frequency signal:
1. Apply the reference signal to I N P U T jack and set each
control for a normal display. Adjust the V O L T S / D I V
and V A R I A B L E controls to obtain an easily observed
waveform display.
Adjust the S W E E P T I M E / D I V and
V A R I A B L E controls so that one cycle of the reference
signal occupies exactly a few scale divisions. After this,
do not to disturb the setting of the V A R I A B L E control.
2. Divide the period of the reference signal by the product
of the horizontal distance (in divisions) and S W E E P
T I M E / D I V given in step 1 above.
Sweep coefficient
Period of reference signal (sec)
~ Horizontal distance ( d i v ) x S W E E P T I M E / D I V setting
3. Remove the reference signal and input the
signal. Adjust the S W E E P T I M E / D I V control for easy
observation.
Measure the horizontal distance of one cycle in divisions
and use the following relationship to calculate the period
of the unknown signal.
Period of the unknown signal = Horizontal distance of
1 cycle (div) x Horizontal sweep coefficient x S W E E P
T I M E / D I V setting
[ E X A M P L E ]
For
the example shown in Fig. 27, S W E E P T I M E / D I V
setting is 0.1 ms and a reference signal of 1.75 k H z is ap-
plied. Adjust the variable control so that the distance of
one cycle is 5 divisions.
Horizontal coefficient = J '
5 x 0.1 (ms)
The unknown signal was then measured. If the S W E E P
T I M E / D I V setting was 0 . 2 ms and the distance is 7 div,
then
Pulse width = 7 (div) x 1 . 1 4 2 x 0 . 2 (ms) * 1.6 ms
30
unknown
1
7
^ [
k
.
H z
\ = 1.142
R e f e r e n c e s i g n a l
A d j u s t e d r e f e r e n c e signal
U n k n o w n s i g n a l
Fig. 27
X-Y OPERATION
P H A S E M E A S U R E M E N T
Phase measurements may be made with X - Y operation.
Typical applications include the circuits designed to pro-
duce a certain phase shift, and the measurement of phase
shift distortion in audio amplifiers.
Distortion of amplitude can be measured at the same time.
T o
make phase measurements, use the following proce-
dure:
1. Apply a sine wave of small distortion to the audio cir-
cuit to be tested.
2. Set the signal generator output to the normal operat-
ing level of the circuit under test. Observe the circuit's
output on the screen. If the test circuit is overdriven,
the sine wave display is clipped and the signal level must
be lowered.
3. Connect the C H 1 probe to the output of the test circuit.
4. Set the M O D E selector to X - Y .
5. Connect the probe to the input of the circuit under test.
6. Adjust the channel 1 and 2 gains for a suitable size of
the Lissajous' pattern.
7. Some typical results are shown in Fig. 29. If the two
signals are in phase, the Lissajous' pattern is a straight
diagonal line.
If the vertical and horizontal gain are
properly adjusted, this line is at a 45° angle.
A 90° phase shift produces a circuliar Lissajours' pat-
tern.
Phase shift of more than 90° produces an elliptical
Lissajours' pattern.
The amount of phase shift is cal-
culated from the
measurement, using the following
formula:
Formula for phaze difference calculation:
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