GW Instek GFC-8010H - Manual (Page 6)

FREQUENCY COUNTER
USER MANUAL
9
(a) When unknown signal is distorted
(b) When high frequency noise superimposed on unknown signal
Fig. 4
FREQUENCY COUNTER
USER MANUAL
10
The erroneous counting can be prevented by satisfying two conditions
below:
a) To make peak-to-peak value of the noise voltage smaller than V
H
.
b) When peak-to-peak value of unknown signal is larger than V
H
, perform
measurements by first setting SENSITIVITY to 1/10, then set it to 1/1
range to protect the input circuit and avoid erroneous counting. One
good method is to conduct measurements at the smallest possible input
within the counter display value “dispersion” range. When the signal is
a pure waveform, it will not occur erroneous counting with any
magnitude input lower than the input destroyed voltage.
5-2. Input Sensitivity Characteristic
The input sensitivity of this instrument is shown as Fig. 5.
Fig. 5 Input Sensitivity Characteristic