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What does PCM stand for?


tommyboy

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PCM does a "Sample" of the analog signal and then converts the sample into a binary (digital pulse) word, that can then be stored or transferred across various media digitally, then decoded and converted back to analog for output to speakers.

Depending upon how many times the signal is sampled you will get more and more accurate represenatation of the complex analog signal. The tecnology was developed and originally used by the telecommunications industry in the late 60s early 70s to convert voice telephone conversations to digital for transmission over telephone lines in a 24 channel per set of wires bit stream. There, they found that a 4000 times per second "sampling" rate was adequate for excellent representation of a 300kz to 3khz voice telephone line.

Since then, sampling at higher sampling rates has been used in the audio industry to build all of these PCM based standards we have. Obviously a PCM based singal sampled at 192,000 times per second creates a lot of binary words and a LOT of data that needs to be stored and/or transmitted, but it's all to the good when the signal can be accurately decoded and converted back to analog.

Cheap DACs (digital to analog converters) will give you cheap sound, regardless of the quality of the signal input. Hence, not all CD, DVD or Blu-Ray devices are equal, you still need a high quality audio out signal for excellent sound quality.

Maybe more information than you wanted, but it helps to understand the numbers.

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