PCM (Pulse-code modulation) Pulse coding modulation, pcm Pulse Coding modulation

PCM (Pulse-code modulation) Pulse coding modulation, pcm Pulse Coding modulation

In audio processing, we often hear PCM data. What is PCM Data?
PCM data is a digital signal after the analog signal passes through PCM. PCM is the process of converting the audio signal from analog signal (time continuous, value continuous) to digital signal (time discrete, value discrete. Digital signals have many advantages, so generally transmitted signals are digital signals.
PCM, also known as pulse coding modulation, must be sampled, quantified, and encoded.

Sampling

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Sampling is the process of multiplying a pulse signal and the sampled signal in the time domain. The time continuous digital signal is converted into a time discrete digital signal.

Quantization

Quantization is the process of changing the continuous sampling value on the value to the discrete level value. There are many methods for quantization, such as linear quantization, A rate, and μ rate.

Linear Quantization

The Quantization interval is a constant.

A-rate PCM

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It can be seen that the rate is relatively high for the level discrimination near the 0 level, which also conforms to the distribution law of general digital signals.
This encoding is an international standard.

μ-rate PCM

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Divide the y axis evenly into 8 segments, when y = I/8, x = (2 * i-1)/255
This encoding is used in Japan and the United States.

Terms

Sampling frequency: the reciprocal of the sampling pulse interval. The sampling frequency cannot be twice the channel frequency.
Sampling depth: Also known as bit depth, which is expressed by several bits for each vertex. Generally, the higher the sampling depth, the more accurate the description of the signal level value.

Reference

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