Hioki 8807-01 - Page 331

APPENDIX 5
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Appendix 2 Reference
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APPX
IND
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Sampling period
Observed waveform
Actual input signal
Si
g
nal fre
q
uenc
y
Sam
p
lin
gp
oints
Aliasing
If the frequency of the signal being measured is
significantly higher than the sampling rate, it is possible for
sampling to produce an apparent signal which is actually
nonexistent. This phenomenon is termed aliasing.
When using the memory recorder function, because the
sampling period for the time axis range may vary widely,
care should be taken in setting the range not to produce
aliasing.
The measurement frequency limit is determined by the
setting of the time axis range. In any event, it is always
best to use the highest practicable sampling rate.
When measuring a repeating signal, using the auto ranging
function is another useful technique.
Measurement Limit Frequency
As a general rule, to ensure that sampling catches the peaks
of a typical sine wave input on the display, more than 25
samples are required for each input cycle.
The measurement limit frequency changes depending on the
time axis range.