User manual

UniversitàdegliStudidiCatania
IntroductiontoNILabVIEW
 DAQ:ADC&DAC
Aliasing has the effect of introducing frequencies into your data that didn't exist in the real‐world signal
(and removing some that did), thereby severely distorting your signal. Once you have aliased data, you
can never go back: There is no way to remove the "aliases." That's why it's so important to sample at a
high‐enough rate.
Howdoyou
determinewhat
yoursampling
rateshouldbe?
Nyquist'sTheorem
Toavoidaliasing,thesamplingrate
mustbegreaterthantwicethe
maximumfrequencycomponentin the
signaltobeacquired.
Nyquist'sTheorem
Toavoidaliasing,thesamplingrate
mustbegreaterthantwicethe
maximumfrequencycomponentin the
signaltobeacquired.
The Nyquist Theorem only deals with accurately representing the frequency of the signal. It doesn't say
anything about accurately representing the shape of your signal. To adequately preserve the shape of
your signal, you should sample at a much higher rate than the Nyquist frequency, generally at least 5 or
10 times the maximum frequency component of your signal.
DIEEI