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Fig. 4 0
1 2 . R E L A T I V E M E A S U R E M E N T S
If the frequency and amplitude of some reference signal are
k n o w n , an unknown signal may be measured for level and
frequency without use of the V O L T S / D I V or
T I M E / D I V 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 w a v e f o r m display.
Adjust the V O L T S / D I V and V A R I A B L E so that the signal
coincides with the C R T f a c e ' s graduation lines. After ad-
justing, be sure not to disturb the setting of the V A R I A -
B L E control.
2. T h e vertical calibration coefficient is now the reference
signal's amplitude (in volts) divided by the product of the
vertical amplitude s e t in step 1 and the V O L T S / D I V
setting.
Using the formula:
Vertical coefficient
Voltage of the reference signal (V)
Vertical amplitude (div) x V O L T S / D I V setting
3 . Remove the reference signal and apply the unknown sig-
nal to the INPUT j a c k , using the V O L T S / D I V control to
adjust the display for e a s y observation. Measure the am-
plitude of the displayed w a v e f o r m and use the follow-
ing relationship to calculate the actual amplitude of the
unknown w a v e f o r m .
Using the formula:
Amplitude of the u n k n o w n signal (V)
= Vertical distance (div) x Vertical coefficient
x V O L T S / D I V setting
3 0
R e f e r e n c e signal
S W E E P
[EXAMPLE]
For the example, the V O L T S / D I V is 1 V/div.
T h e reference signal is 2 V r m s . Using the V A R I A B L E , ad-
just so that the amplitude of the reference signal is 4 divi-
sions. (See Fig. 4 1 )
Substituting the given value:
. . . .
Vertical coefficient =
T h e n measure the unknown signal and V O L T S / D I V is 5 V
and vertical amplitude is 3 divisions.
Substituting the given value:
Effective value of unknown signal = 3 (div) x 0 . 5 x 5(V/div)
•
Period
Setting the relative sweep coefficient with respect to a refer-
ence frequency signal.
Procedure:
1. Apply the reference signal to the INPUT j a c k , using the
V O L T S / D I V and V A R I A B L E to obtain an easily observed
w a v e f o r m display.
Using the S W E E P T I M E / D I V and V A R I A B L E adjust one
cycle of the reference signal to occupy a fixed number
of scale divisions accurately. After this is done be sure
not to disturb the setting of the V A R I A B L E control.
Adjusted reference signal
U n k n o w n signal
Fig. 4 1
. . . .
2 V r m s
4 (div) x 1 (V/div)
= 0 . 5
= 7.5 V rms
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