Page "Signal-to-noise ratio" Paragraph 32

When a measurement is digitised, the number of bits used to represent the measurement determines the maximum possible signal-to-noise ratio.

This is because the minimum possible noise level is the error caused by the quantization of the signal, sometimes called Quantization noise.

This noise level is non-linear and signal-dependent ; different calculations exist for different signal models.

Quantization noise is modeled as an analog error signal summed with the signal before quantization (" additive noise ").