ADC Sampling Frequency:

The Sampling Frequency is another critical parameter of the systems. Usually the ADC manufacturer specifies this in SPS (samples per second). The waveform at the input of the ADC might not stay constant. It might remain constant for long periods of time or change continuously (as with a voice at the input). When we sample the data, if it doesn’t change, we can sample once. However, it is more likely that we will setup the ADC to sample regularly. Different signals at the input of the ADC will require different sampling speeds. It is possible to oversample by sampling at a very high speed and therefore be able to capture different signals.

Realize that if not sampling fast enough, very quick events can not be detected. Speech signals for example are generally considered to have important information for the region of 300Hz to 4000Hz. Using Nyquist’s theorem we realize that we must therefore sample at a frequency twice the highest frequency (This is for low pass signals, i.e. signals where the lowest frequency is relatively close to 0Hz).