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1 1 . FREQUENCY MEASUREMENTS
Frequency measurements are made by measuring the
period of one cycle of waveform and taking the reciprocal
of this time value a s the frequency.
Procedure:
1 . Following the proceudre described in section 5 " T i m e
Measurements", measure the time of each cycle. The
figure obtained in the signal period.
2. The frequency is the reciprocal of the period measured.
Using the formula:
Freq -
p
j
j
e r
o c
1 cycle = 4 0 jis (5 /ts/div. x 8 div.)
Fig. 3 3
[EXAMPLE]
A period of 4 0
is observed and measured. (See Fig. 3 3 )
JJLS
Assuming that S W E E P T I M E / D I V indicates 5 ^s/div,
substituting the given Value:
F r e q = 1 / [ 4 0 x 1 0 "
6
] = 2 . 5 x 1 0
While the above method relies on the measurement directly
of the period of one c y c l e , the frequency may also be
measured by counting the number of cycles present in a
given time period.
1 . Apply the signal to the INPUT jack. Set the vertical
MODE to the channel to be used and adjusting the
various controls for a normal display. Set the V A R I A B L E
control to C A L position.
2. Count the number of cycles of waveform between a
chosen set of graticules in the vertical axis direction.
Using the horizontal distance between the vertical lines
used above and the S W E E P T I M E / D I V , the time span
may be calculated. Multiply the reciprocal of this value
by the number of c y c l e s present in the given time span.
If " x 10 M A G " is used multiply this further by 1 0 .
Note that errors will occur for displays having only a f e w
cycles.
26
4
= 2 5 kHz
Using the formula:
# of c y c l e s x " x 10 M A G " value
Freq=
Horizontal distance (div) x S W E E P T I M E / D I V setting
Count cycles between this portion
Fig. 3 4
[EXAMPLE]
For the example, within 7 divisions there are 1 0 cycles.
The S W E E P T I M E / D I V is 5 /xs/div. (See Fig. 3 4 )
Substituting the given value:
10
Freq =
7 (div) x 5 (/ts/div)
= 2 8 5 . 7 kHz
Cursor measurement
1 . Apply the signal to INPUT jack, setting the vertical
MODE switch to the channel to be used and adjusting
the various controls for a normal display.
V O L T S / D I V and S W E E P T I M E / D I V to obtain an easily
observed display.
Set the V A R I A B L E to C A L .
2. Set the cursor mode to 1A4T.
3 . Adjust the A R E F cursor to the left of the points to
be measured, and the A cursor to the right.
4 . Measured value is displayed in the upper part on the
screen posterior to 1 /AT.
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