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Fig. 40
12.RELATIVE
MEASUREMENTS
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 ad-
justing, be sure not to disturb the setting of the VARIA-
BLE control.
2. The vertical calibration coefficient is now the reference
signal's amplitude (in volts) divided by the product of the
vertical amplitude
set in step 1 and the VOLTS/DIV
setting.
Using the formula:
Vertical coefficient
=
Voltage of the reference signal (V)
Vertical amplitude (div)
x VOLTS/DIV
setting
Using the formula:
Amplitude of the unknown signal (V)
= Vertical distance (div)
x Vertical coefficient
x VOLTS/DIV setting
30
Adjusted reference signal
Reference signal
[EXAMPLE]
For the example, the VOLTS/DIV is 1 V/div.
The reference signal is 2 Vrms. Using the VARIABLE, ad-
just so that the amplitude of the reference signal is 4 divi-
sions. (See Fig. 41)
Substituting the given value:
=0.5
Then measure the unknown signal and VOLTS/DIV is 5 V
and vertical amplitude is 3 divisions.
Substituting the given value:
Effective value of unknown signal = 3 (div) x0. 5 x 5(V/div)
=7.5 Vrms
* Period
Setting the relative sweep coefficient with respect to a refer-
ence frequency signal.
Procedure:
1. Apply the reference signal to the INPUT jack, using the
VOLTS/DIV and VARIABLE to obtain an easily observed
waveform display.
Using the SWEEP TIME/DIV and VARIABLE 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 VARIABLE control.
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