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I R E F c u r s o r
10. TIME RATIO MEASUREMENT
The following describes procedures for measuring duty ra-
tio of square w a v e s , etc.
1)
Apply the signal to the input connector. Select the chan-
nel to be used with the V E R T I C A L M O D E , set the
A C / D C s w i t c h to D C , deactivate the GND s w i t c h , and
adjust each control for the normal s w e e p display. T h e n ,
adjust the V O L T S / D I V and S W E E P T I M E / D I V to obtain
proper w a v e f o r m observation.
Adjust the one cycle width of the signal to 5 divisions
2)
with the S W E E P TIME V A R I A B L E . If necessary, use the
•
P O S I T I O N .
3)
Select the AT cursor mode with the C U R S O R S .
NOTE: Time ratio can be measured if the S W E E P T I M E
is not set to C A L .
4)
Adjust the AHEF cursor to the left of the points to be
measured and the Zicursor to the right.
5)
Measured duty ratio supposing 5 divisions as 1 0 0 % is
displayed in percentage following RATIO in the upper
right of the C R T .
R E F c u r s o r
Fig. 4 3
M e a s u r e d v a l u e -
c u r s o r
F i g .
4 2
M e a s u r e d v a l u e .
. c u r s o r
1 1 . FREQUENCY MEASUREMENT
(1) Normal Procedures
Since frequency is a reciprocal of a period, it can be deter-
mined by measuring time of one c y c l e .
1)
Measure time of one cycle according to the procedures
mentioned in section 5 T I M E M E A S U R E M E N T . T h e
measured time is a period of the signal.
2)
Calculate a reciprocal of the measured time to deter-
mine frequency as follows:
Frequency =
-
Period
P e r i o d o f 1 c y c l e =
[EXAMPLE]
Supposing the measured period is 4 0 us and S W E E P
T I M E / D I V setting is 5 ns/dlv in the example s h o w n in
Fig. 0 0 ,
Frequency =
-
4 0
x
The above method s h o w s how to determine frequency
based on a measured period of a c y c l e . Frequency can also
be determined by counting the number of cycles on the C R T .
1 )
Apply the signal to the input connector. Select the chan-
nel to be used w i t h the V E R T I C A L M O D E , and adjust
each control for the normal s w e e p display. Set the
V A R I A B L E used channel and S W E E P T I M E to C A L con-
dition.
2)
Count the number of cycles between any vertical gradu-
ation lines. Find time of the c y c l e s from the horizontal
distance between the lines and S W E E P T I M E / D I V set-
ting. Multiple a reciprocal of the time by the number
of c y c l e s . T h i s method, h o w e v e r , will c a u s e measure-
ment errors for signals w i t h a f e w number of c y c l e s .
n
Frequency =
x S W E E P TIME/DIV setting
[EXAMPLE]
In the example s h o w n in Fig. 4 5 , 10 c y c l e s cove 7 di-
visions.
If S W E E P T I M E / D I V setting is 5 ^s/div,
c
Frequency =
7 (div) x 5 (/is/div)
4 0 / i s ( 5 j t s / d i v x 8 d i v )
Fig. 4 4
4
-
= 2 . 5 x 1 0
= 2 5 kHz
6
1 0 "
Number of c y c l e s
1
Horizontal distance
1 0
- - -
2 8 5 . 7 kHz
3 3
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