User manual

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.
DIEEI