Nyquist rate

These terms refer to the nyquist sampling theorem, but are used in different ways by different authors. They can be used to mean four different things depending on author:

• The highest frequency contained in a signal
• Twice the highest frequency contained in a signal
• the sampling rate
• One-half the sampling rate.

Nyquist sampling theorem:

Often called just sampling theorem or sometimes shannon sampling theorem

A continuous signal (analog signal) can be properly sampled, only if it does not contain frequency components above one-half of the sampling rate. This means that with cd-audio's 44.1kHz sampling rate, the maximum frequency that can be represented properly is 22.05kHz.