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While the above method relies on the measurement direct-
ly of the period of one cycle, the frequency may also be
measured by counting the number of cycles present in a
given time period.
1. Apply the signal to INPUT jack, setting the vertical
M O D E s w i t c h to the channel to be used and adjusting
the various controls for a normal display S e t the V A R I -
A B L E control to CAL.
2. Count the number of cycles of waveform between a
chosen set of vertical graduation lines.
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 cycles present in the given time span.
If " x 1 0 M A G " is used multiply this further by 10.
Note that errors will occur for displays having only a
f e w cycles.
Using the formula:
# of cycles x " x 1 0 M A G " value
Freq =
Horizontal distance (div) x S W E E P TIME/DIV setting
[ E X A M P L E ]
For the example s h o w n in Fig. 14, within 7 divisions there
are 1 0 cycles.
T h e S W E E P T I M E / D I V setting is 5 /is.
Substituting the given value:
F r e q = _
= 2 8 5 . 7 kHz
1°.
7 x 5
(/us)
t
Count c y c l e s b e t w e e n ,
t h i s portion
Fig. 14
P U L S E W I D T H
M E A S U R E M E N T S
Procedure:
1. Apply the pulse signal to INPUT jack and select the ver-
tical M O D E s w i t c h to the channel to be used.
2. Use V O L T S / D I V , V A R I A B L E and ^ POSITION controls
to adjust the waveform s u c h that the pulse is easily ob-
served and s u c h that the center pulse width coincides
with the center horizontal line on the C R T screen.
3. Measure the distance between the intersection of the
pulse waveform and the center horizontal line in divi-
sions. Be sure that the A V A R I A B L E control is in the
A P P L I C A T I O N
C A L position. Multiply this distance by the A S W E E P
T I M E / D I V control and by 1 / 1 0 is " x 1 0 M A G " mode is
being used.
Using the formula:
Pulse width = Horizontal distance (div) x ( S W E E P T I M E /
[ E X A M P L E ]
For the example s h o w n in Fig. 1 5, the distance (width) at
the center horizontal line is 4.6 divisions and the A
S W E E P . T I M E / D I V setting is 0.2 ms.
Substituting the given value:
Pulse width = 4.6 (div) x 0.2 ms = 0 . 9 2 m s
P U L S E R I S E T I M E A N D
M E A S U R E M E N T S
For risetime and falltime measurements, the 1 0 % and 9 0 %
amplitude points are used as starting and ending reference
points.
Procedure:
1. Apply a signal to INPUT jack and select the vertical
MODE s w i t c h to the channel to be used.
Use the V O L T S / D I V and V A R I A B L E controls to adjust
the waveform peak to peak height to six divisions.
2. Using the y POSITION control and the other controls,
adjust the display s u c h that the waveform is centered
vertically in the display. S e t the S W E E P T I M E / D I V c o n -
trol to a s fast a setting a s possible consistent w i t h ob-
servation of both the 1 0 % and 9 0 % points. S e t the A
V A R I A B L E control to C A L .
3. Use the <>• POSITION control to adjust the 1 0 % point
to coincide with a vertical graduation line and measure
the distance in divisions between the 1 0 % and 9 0 %
points on the waveform. Multiply this by the S W E E P
T I M E / D I V and also by 1 / 1 0 , if " x 1 0 M A G " made w a s
used.
N O T E :
Be sure that the correct 1 0 % and 9 0 % lines are used.
For s u c h measurements the 0,10, 9 0 and 1 0 0 % points
are marked on the C R T screen.
DIV setting) x " x M A G 1 0 " value ^ ( 1 / 1 0 )
A d j u s t t o the vertical s c a l e
.with < > P O S I T I O N
• Align t h e w a v e f o r m w i t h t h e
Pulse length (at 5 0 % )
center using ^ P O S I T I O N
Fig. 15
I E
F A L L T I
2 1
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