Pulse code modulation

Pulse Code Modulation (PCM) is a digital representation of an analog signal. The signal is sampled at a sampling frequency f_s. This means the value of the signal, a sample, is captured at uniform distances T (= 1/f_s). Every sample is quantised to a discrete number of possible values. Where the number of possible values is two, the code is said to be a [binary code]?.

PCM is used in digital telephone systems or for digital audio recording on compact discs CD.

Differential (or Delta) Pulse Code Modulation (DPCM) encodes the PCM values as differences between the current and the previous value. For audio this type of encoding reduces the number of bits required per sample compared to PCM by about 25%.

See modulation for other examples of modulation techniques.

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