Duratech DA05 WinCE Manual do Utilizador descarregar pdf (Página 39)

UniversitàdegliStudidiCatania

IntroductiontoNILabVIEW

 DAQ:Sampling

Real‐world signals are continuous things. To represent these signals in your computer, the

DAQ device has to check the level of the signal every so often and assign that level a

discrete number that the computer will accept; this is called an analog‐to‐digital

conversion. The computer then sort of "connects t he dots" and, h opefully, gives you

something that looks similar to the real‐world signal (that's why we say it represents the

signal).

The sampling rate of a system simply reflects how often an analog‐to‐digital conversion

(ADC) takes place. When the sampling rate isn't high enough, a scary thing happens.

Aliasing, while not intuitive, is easy to observe. If we sample 8.5 times slower (the circles),

our reconstructed signal looks nothing like the original.

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Duratech DA05 WinCE Manual do Utilizador Página 39