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P H A S E D I F F E R E N C E M E A S U R E M E N T S
This procedure is useful in measuring the phase difference
of signals of the same frequency.
Procedure:
1. Apply the two signals to the CH1 and CH2 INPUT jacks,
setting the vertical MODE to either CHOP or ALT mode.
2. Set the SOURCE to the signal which is leading in phase
and use the VOLTS/DIV to 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 SWEEP VARIABLE to ad-
just the display such that one cycle of the signals oc-
cupies 8 divisions of horizontal display.
A
Use the y 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 two waveforms.
Using the formula:
Phase difference - Horizontal distance (div) x 45°/div
1 cycle
Reference signal
Comparison
signal
Fig. 26
[EXAMPLE]
For the example, the horizontal distance is 1.7 divisions.
(See Fig. 26)
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.
In this case, the phase difference can be obtained from the
SWEEP TIME/DIV setting for 8 divisions/cycle and the new
SWEEP TIME/DIV setting changed for higher accuracy, by
useing the following formula.
2 4
Phase difference
Phase difference = Horizontal distance of new sweep range
(div)x45°/div
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 MAG for a scale of 4.5°/div.
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 .
Phase difference
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. 27
R E L A T I V E M E A S U R E M E N T
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 to 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 with the CRT face's graduation lines. After
adjusting, be sure not to disturb the setting of the
VARIABLE control.
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