oversampling ratio (ADU) (OSR)

The sampling the orem plays a decisive role in the digitization of analog signals because it defines the relationship between sampling rate and reproducible signal frequency.

The sampling theorem is fulfilled if the sampling rate is at least twice as high as the signal frequency to be digitized. If the sampling rate is higher than that specified by the sampling theorem, this is referred to as oversampling. The oversampling factor, or oversampling ratio (OSR), indicates the factor by which the sampling rate is higher than the sampling rate that satisfies the sampling theorem.

When digitizing audio, the sampling theorem is satisfied by a sampling rate greater than 40 kHz, but if the audio signal is sampled at 80 kHz, for example, the OSR factor is 2.