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[ E X A M P L E ]
For the example shown in F i g . 18, suppose that a period of
4 0 jus was observed and measured. Then the frequency is:
F r e q = 1 / [ 4 0 x 1 0 "
6
] = 2 . 5 x 1 0
While the above method relies on the direct measurement
of the period of one cycle, the frequency may also be
measured by counting the number of cycles present on the
screen in a given time period.
1. Apply the signal to I N P U T jack, setting the vertical
M O D E switch 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 .
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 setting, the time
span for the cycles can be calculated. Multiply the
reciprocal of this value by the number of cycles present
in the given time span. If " x 10 M A G " is used, multiply
this further by 10.
Note that errors will occur for a display having only a
few cycles.
No. of c y c l e s x " x 10 M A G " value (10)
r e q
Horizontal distance ( d i v ) x S W E E P T I M E / D I V setting
[ E X A M P L E ]
For the example shown in F i g . 1 9 , there are 10 cycles with-
in 7 divisions.
Suppose that the S W E E P T I M E / D I V setting is 5 /is.
Freq = - — ^ —
= 285.7 k H z
(us)
v
7 x 5
C o u n t c y c l e s b e t w e e n
t h i s p o r t i o n
26
4
= 2 5 kHz
Fig. 19
PULSE WIDTH MEASUREMENTS
Pulse width can be measured as follows:
Procedure:
1. Apply the pulse signal to I N P U T jack and select the ver-
tical M O D E switch 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 *
trols to adjust the waveform such that the pulse is easily
observed and such that the center horizontal
on the screen is at the middle of the pulse amplitude.
3 . Measure the distance between the horizontal distance
between the two points on the pulse waveform which
cross the center horizontal line. Be sure that the V A R I -
A B L E control is in the C A L position.
distance by the S W E E P T I M E / D I V control.
further by 1/10 if " x 10 M A G " is used.
Pulse width = Horizontal distance (div) x ( S W E E P T I M E /
D I V setting) x " x 1 0 M A G " v a l u e "
[ E X A M P L E ]
For the example shown in Fig. 2 0 , the distance (width) of
the center horizontal line segment crossing the pulse wave-
form is 4.6 divisions.
Suppose the S W E E P T I M E / D I V
setting is 0.2 ms.
Pulse width = 4.6 (div) x 0.2 ms = 0.92 ms
A d j u s t t o t h e v e r t i c a l s c a l e
w i t h « « •
P u l s e l e n g t h ( a t 5 0 % )
Fig. 20
PULSE RISETIME AND F A L L T I M E
MEASUREMENTS
For risetime and falltime measurements, the 10% and 90%
amplitude points are used as starting and ending reference
points.
Procedure:
1. Apply a signal to I N P U T jack and select the vertical
M O D E switch to the channel to be used.
P O S I T I O N con-
graticule
Multiply this
Multiply
1
(1/10)
P O S I T I O N
C e n t e r t h e w a v e f o r m
u s i n g *
P O S I T I O N
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