Pulse-codemodulationFromWikipedia,thefreeencyclopediaJumpto:HYPERLINK"http://en.wikipedia.org/wiki/Pulse-code_modulation"\l"mw-head#mw-head"navigation,HYPERLINK"http://en.wikipedia.org/wiki/Pulse-code_modulation"\l"p-search#p-search"search"PCM"redirectshere.Forotheruses,seeHYPERLINK"http://en.wikipedia.org/wiki/PCM_(disambiguation)"\o"PCM(disambiguation)"PCM(disambiguation).Pulse-codemodulation(PCM)isamethodusedtoHYPERLINK"http://en.wikipedia.org/wiki/Digital"\o"Digital"digitallyrepresentsampledHYPERLINK"http://en.wikipedia.org/wiki/Analog_signal"\o"Analogsignal"analogsignals.ItisthestandardformforHYPERLINK"http://en.wikipedia.org/wiki/Digital_audio"\o"Digitalaudio"digitalaudioincomputersandvariousHYPERLINK"http://en.wikipedia.org/wiki/Blu-ray"\o"Blu-ray"Blu-ray,HYPERLINK"http://en.wikipedia.org/wiki/Compact_Disc"\o"CompactDisc"CompactDiscandHYPERLINK"http://en.wikipedia.org/wiki/DVD"\o"DVD"DVDformats,aswellasotherusessuchasdigitalHYPERLINK"http://en.wikipedia.org/wiki/Telephone"\o"Telephone"telephonesystems.APCMstreamisadigitalrepresentationofananalogsignal,inwhichthemagnitudeoftheanaloguesignalissampledregularlyatuniformintervals,witheachsamplebeingHYPERLINK"http://en.wikipedia.org/wiki/Quantization_(signal_processing)"\o"Quantization(signalprocessing)"quantizedtothenearestvaluewithinarangeofdigitalsteps.PCMstreamshavetwobasicpropertiesthatdeterminetheirfidelitytotheoriginalanalogsignal:theHYPERLINK"http://en.wikipedia.org/wiki/Sampling_rate"\o"Samplingrate"samplingrate,whichisthenumberoftimespersecondthatsamplesaretaken;andtheHYPERLINK"http://en.wikipedia.org/wiki/Audio_bit_depth"\o"Audiobitdepth"bitdepth,whichdeterminesthenumberofpossibledigitalvaluesthateachsamplecantake.HistoryInthehistoryofelectricalcommunications,theearliestreasonforsamplingasignalwastointerlacesamplesfromdifferentHYPERLINK"http://en.wikipedia.org/wiki/Telegraphy"\o"Telegraphy"telegraphysources,andconveythemoverasingletelegraphcable.Telegraph