Question

What is the advantages and disadvantages of :

- critical sampling.

- over-sampling.

- under-sampling.

Answer 1

over-sampling

advantages

increases the frequency spacing between the aliases of the signal, thus reducing the design requirements on the anti-aliasing filter.

Another advantage is with the phase characteristic. A sharp transition band introduces nonlinearity in the phase characteristic near the transition region.

disadvantages

sampled signal contain noise .

higher speed required for the ADC and the processing unit

under-sampling

advantages

the power consumption for the ADC is lower.

easy capturing of ADC data due to relaxed setup and hold times, and easy interface to FPGAs due to lower speeds.

disadvantages

the response of a digital system to a delta function is not spatially invariant and therefore does not fulfill certain technical requirements of classical analysis

The Noise Equivalent Quanta (NEQ) loses its common meaning as maximum available SNR2 (signal-to-noise) at a particular frequency.

critical sampling

advantages

It is sampled at the Nyquist frequency.

free from harmonics

disadvantages

very difficult to obtain and relitave higher cost is involved