Sampling below twice the highest frequency causes aliasing distortion.
Evidence
When converting between analogue and digital signals, the sampling theorem (or the Nyquist theorem) requires that the sampling rate must be at least twice as high as the highest signal component to be converted. Otherwise aliasing will occur, whereby signal components of frequency higher than the Nyquist frequency (half of the sampling rate) will be mirrored to below the Nyquist frequency, thus distorting the signal. To avoid aliasing, an A/D-converter normally includes a low-pass filter that yields enough attenuation above the Nyquist frequency. — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 404
Categorization
Category: Definitional Content
- DEFINE: Concise statement of the Nyquist sampling theorem and the aliasing mechanism it prevents.