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PHASE DIFFERENCE MEASUREMENTS
This procedure is useful in measuring the phase difference
of signals of the same frequency.
Procedure:
1. Apply the t w o signals t o the CH1 and CH2 INPUT jacks,
setting the vertical MODE t o either CHOP or ALT mode.
2. Set the SOURCE t o the signal which is leading in phase
and use the VOLTS/DIV t o adjust the signals such that
they are equal in amplitude. Adjust the other controls for
a normal display.
3. Use the SWEEP TIME/DIV and VARIABLE t o adjust the
display such that one cycle of the signals occupies 8
divisions of horizontal display.
Use the • POSITION to bring the signals in the center of
the screen.
Having set up the display as above, one division now
represents 4 5 ° in phase.
4 . Measure the horizontal distance between corresponding
points on the t w o waveforms.
Using the formula:
Phase difference = Horizontal distance (div) x 4 5 ° / d i v
Reference signal
Comparison
"signal
Fig. 2 1
[EXAMPLE]
For the example, the horizontal distance is 1.7 divisions.
(See Fig. 21)
Substituting the given value:
The phase difference = 1.7 (div) x 4 5 ° / d i v = 7 6 . 5 °
The above setup allows 4 5 ° per division but if more ac-
curacy is required the SWEEP TIME/DIV may be changed
and magnified without touching the VARIABLE control and
if necessary the trigger level can be readjusted.
For this type of operation, the relationship of one division t o
4 5 ° no longer holds. Phase difference is defined by the for-
mula as follows.
22
1 cycle
Phase difference
Phase difference = Horizontal distance of new sweep range
( d i v ) x 4 5 ° / d i v
New SWEEP TIME/DIV setting
x
Original SWEEP TIME/DIV setting
Another simple method of obtaining more accuracy quickly
is to simply use x 10 M A G for a scale of 4 . 5 ° / d i v .
RELATIVE MEASUREMENTS
If the frequency and amplitude of some reference signal are
known, an unknown signal may be measured for level and
frequency
without
use of the VOLTS/DIV or SWEEP
TIME/DIV for calibration.
The measurement is made in units relative t o the reference
signal.
•
Vertical Sensitivity
Setting the relative vertical sensitivity using a reference
signal.
Procedure:
1. Apply the reference signal to the INPUT jack and adjust
the display for a normal waveform display.
Adjust the VOLTS/DIV and VARIABLE so that the signal
coincides w i t h the CRT face's graduation lines. After
adjusting, be sure not t o disturb the setting of the
VARIABLE control.
Phase difference
O n e c y c l e a d j u s t e d t o o c c u p y 8 d i v .
E x p a n d e d s w e e p w a v e f o r m d i s p l a y .
Fig. 2 2
—
Phase difference
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