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Pulse-code modulation (PCM) is a method used to digitally represent analog signals. It is the standard form of digital audio in computers, compact discs , digital telephony and other digital audio applications.
Digital modulation methods can be considered as digital-to-analog conversion and the corresponding demodulation or detection as analog-to-digital conversion. The changes in the carrier signal are chosen from a finite number of M alternative symbols (the modulation alphabet). Schematic of 4 baud, 8 bit/s data link containing arbitrarily chosen ...
Differential pulse-code modulation (DPCM) is a signal encoder that uses the baseline of pulse-code modulation (PCM) but adds some functionalities based on the prediction of the samples of the signal. The input can be an analog signal or a digital signal .
Demodulation is the process of extracting the original information-bearing signal from a carrier wave. A demodulator is an electronic circuit (or computer program in a software-defined radio) that is used to recover the information content from the modulated carrier wave. [1] There are many types of modulation, and
"Communication system utilizing constant amplitude pulses of opposite polarities" by Maurice Deloraine et. al. (French patent issued 1946, US patent filed 1947). [7] "Differential quantization of communication signals" by C. Chapin Cutler (filed 1950), [8] which describes differential PCM and delta modulation (1-bit DPCM).
Pulse-density modulation, or PDM, is a form of modulation used to represent an analog signal with a binary signal.In a PDM signal, specific amplitude values are not encoded into codewords of pulses of different weight as they would be in pulse-code modulation (PCM); rather, the relative density of the pulses corresponds to the analog signal's amplitude.
A modulator-demodulator, commonly referred to as a modem, is a computer hardware device that converts data from a digital format into a format suitable for an analog transmission medium such as telephone or radio.
The default signal compression encoding on a DS0 is either μ-law (mu-law) PCM (North America and Japan) or A-law PCM (Europe and most of the rest of the world). These are logarithmic compression systems where a 13- or 14-bit linear PCM sample number is mapped into an 8-bit value. This system is described by international standard G.711. Where ...