Pulse-code modulation

Pulse-code modulation (PCM) is a method used to <a href="/facts/Digital_signal_(signal_processing)/bCtTHxre">digitally</a> represent <a href="/facts/Analog_signal/xDbb4uB5">analog signals</a>. It is the standard form of <a href="/facts/Digital_audio/PgugcLAI">digital audio</a> in computers, <a href="/facts/Compact_disc/g51GRloc">compact discs</a>, <a href="/facts/Digital_telephony/2GwTTepw">digital telephony</a> and other digital audio applications. In a PCM <a href="/facts/Stream_(computing)/2jtBAp0U">stream</a>, the <a href="/facts/Amplitude/aEckuXJM">amplitude</a> of the analog signal is <a href="/facts/Sampling_(signal_processing)/xxck7aLN">sampled</a> at uniform intervals, and each sample is <a href="/facts/Quantization_(signal_processing)/fddS3BE2">quantized</a> to the nearest value within a range of digital steps. <a href="/facts/Alec_Reeves/mw1zsd1e">Alec Reeves</a>, <a href="/facts/Claude_Shannon/EremsCws">Claude Shannon</a>, <a href="/facts/Barney_Oliver/VnDPAXKc">Barney Oliver</a> and <a href="/facts/John_R._Pierce/mq8bfrLb">John R. Pierce</a> are credited with its invention.
Linear pulse-code modulation (LPCM) is a specific type of PCM in which the quantization levels are linearly uniform. This is in contrast to PCM encodings in which quantization levels vary as a function of amplitude (as with the <a href="/facts/A-law_algorithm/PI9UC1nc">A-law algorithm</a> or the <a href="/facts/%25CE%259C-law_algorithm/Ve8vJ6mb">μ-law algorithm</a>). Though PCM is a more general term, it is often used to describe data encoded as LPCM.
A PCM stream has two basic properties that determine the stream's fidelity to the original analog signal: the <a href="/facts/Sampling_rate/xxck7aLN">sampling rate</a>, which is the number of times per second that samples are taken; and the <a href="/facts/Audio_bit_depth/24ccTeTT">bit depth</a>, which determines the number of possible digital values that can be used to represent each sample.

Pulse-code modulation open-in-new

Pulse-code modulation