Oversampling

Oversampling is the practice of sampling a signal at a rate significantly higher than the Nyquist rate required by the Nyquist-Shannon sampling theorem. While the theorem guarantees that sampling at twice the maximum frequency is sufficient for perfect reconstruction, oversampling provides practical benefits: it eases the design of anti-aliasing filters by moving the transition band far from the signal bandwidth, and it enables noise-shaping techniques that redistribute quantization error into frequency bands where it can be removed by digital filtering.

Oversampling is the dominant technique in high-resolution audio converters, where delta-sigma modulation achieves effective resolutions of 24 bits or more by sampling at rates hundreds of times above the audio bandwidth. The technique is a practical admission that the ideal conditions of the Nyquist-Shannon theorem are unattainable, and that the best engineering solution is to move the problem to a domain where it is easier to solve.