Editing Quantization (signal processing) (section)

===Analog-to-digital converter===
An [[analog-to-digital converter]] (ADC) can be modeled as two processes: [[Sampling (signal processing)|sampling]] and quantization.  Sampling converts a time-varying voltage signal into a [[discrete-time signal]], a sequence of real numbers.  Quantization replaces each real number with an approximation from a finite set of discrete values.  Most commonly, these discrete values are represented as fixed-point words. Though any number of quantization levels is possible, common word lengths are [[audio bit depth|8-bit]] (256 levels), 16-bit (65,536 levels) and 24-bit (16.8&nbsp;million levels). Quantizing a sequence of numbers produces a sequence of quantization errors which is sometimes modeled as an additive random signal called '''quantization noise''' because of its [[stochastic]] behavior.  The more levels a quantizer uses, the lower is its quantization noise power.