Leader Electronics Corp. LDC-823A Instruction Manual - page 10
such a way so that it will
be
at
tio, such as sine wave, triangular
,
al
added to Schmidt circuit will
eed the lower limit of hysteresis
Upper limit of
- - hysteresis level
DC level
- - __
Lower limit of
hysteresis level
.tio
=
X 100 (%)
to
ease in the du ty ratio. In the
will be approx. 1/5 com-
rement may not be able to be
noise present, and the lower
The measuring range is
in
Table 4-5-1 and Table 4-5-2,
rrange.
-
9999.9999kHz
80000.000kHz
SOOOO.OOkHz
-
99.999999MHz
-
250.00000MHz
-
250.0000MHz
period-measurement is more
4.6
Period measurement
(
1
)
Set the function switch to PERIOD, and apply the signal to the input connector. The
measuring range is lOOmS - O.OOlmS ( 1 J,lS). Period measurement is suitable for accurate
measurement in the frequency range of 10Hz - 1kHz.
(
2
)
By setting the MULTI. and PERIOD as listed in Tables 4-6-1 and 4-6-2, more accurate
measu rements can be accomplished within a short time and longer numerical display
measurement results in a more accurate measurement.
When the measuring time is within IS - O.lS,
Frequency
Period
MULTI
Display
10Hz-100Hz
lOOmS - 10mS
X10
100.0OmS
-
lO.OOmS
100Hz - 1kHz
10mS
-
1mS
X100
10.000mS - 1.000mS
1kHz
-
10kHz
lmS - O.lmS
X1000
1.0000mS - 0.1000mS
Table 4-6-1
When the measuring time is within lOS
-
IS,
Frequency
Period
MULTI
Display
10Hz
-
100Hz
lOOmS
-
10mS
X100
100.000mS - 10.000mS
100Hz - 1kHz
10mS
-
1mS
X1000
10.000Oms - 1.0000mS
Table 4-6-2
Measuring accuracy
The accuracy of period measurement can be expressed as follows:
Accuracy
=
± 1 count ± trigger error ± time base accuracy . . . Equation 4-6-1.
In the above equation, the most important factor is the trigger-error. Trigger-error occurs
with the overlapped signal noise and noise in the counter. During the measurement, when
the display fluctuating range is within ±l, the error can be regarded as ±1 count. If it is
over ±1 count, it may be trigger-error or alteration of the input signal.
As
a checking
method, when the input sensitivity of counter or input voltage is set t6 higher values, if the
variable range becomes less, it can be judged as trigger error.
In order to reduce the effect of.input signal noise the trigger-error can be reduced by
raising the input voltage or by rectifying the input-wave into rectangular wave-form
applying to LDC-S23A.
...... 9 ......