Pulse-code modulation

PCMLPCMLinear PCMpulse code modulationPCM audioLinear Pulse Code ModulationPCM StereoADPCMlinear pulse-code modulationpulse-code modulated
Pulse-code modulation (PCM) is a method used to digitally represent sampled analog signals.wikipedia
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Digital audio

digital musicdigitalaudio
It is the standard form of digital audio in computers, compact discs, digital telephony and other digital audio applications.
In a digital audio system, an analog electrical signal representing the sound is converted with an analog-to-digital converter (ADC) into a digital signal, typically using pulse-code modulation.

Audio bit depth

24-bitbit depthresolution
A PCM stream has two basic properties that determine the stream's fidelity to the original analog signal: the sampling rate, which is the number of times per second that samples are taken; and the bit depth, which determines the number of possible digital values that can be used to represent each sample.
In digital audio using pulse-code modulation (PCM), bit depth is the number of bits of information in each sample, and it directly corresponds to the resolution of each sample.

A-law algorithm

A-lawPCMA
This is in contrast to PCM encodings where quantization levels vary as a function of amplitude (as with the A-law algorithm or the μ-law algorithm).
An A-law algorithm is a standard companding algorithm, used in European 8-bit PCM digital communications systems to optimize, i.e. modify, the dynamic range of an analog signal for digitizing.

Alec Reeves

Alec Harley ReevesAlex Harley ReevesReeves, Alec
British engineer Alec Reeves, unaware of previous work, conceived the use of PCM for voice communication in 1937 while working for International Telephone and Telegraph in France.
Alec Harley Reeves (10 March 1902 – 13 October 1971) was a British scientist best known for his invention of pulse-code modulation (PCM).

SIGSALY

Green Horneta special scramblercomputers of the era
The first transmission of speech by digital techniques, the SIGSALY encryption equipment, conveyed high-level Allied communications during World War II.
It pioneered a number of digital communications concepts, including the first transmission of speech using pulse-code modulation.

Telephony

digital telephonytelephonedigital
It is the standard form of digital audio in computers, compact discs, digital telephony and other digital audio applications.
Following the development of computer-based electronic switching systems incorporating metal–oxide–semiconductor (MOS) and pulse-code modulation (PCM) technologies, the PSTN gradually evolved towards the digitization of signaling and audio transmissions.

T-carrier

T1T-1T1 carrier
The T-carrier system, introduced in 1961, uses two twisted-pair transmission lines to carry 24 PCM telephone calls sampled at 8 kHz and 8-bit resolution.
1957 and first employed by 1962 for long-haul pulse-code modulation (PCM) digital voice transmission with the D1 channel bank.

Time-division multiplexing

TDMtime division multiplexingtime slot
The American inventor Moses G. Farmer conveyed telegraph time-division multiplexing (TDM) as early as 1853.

Gray code

Gray codingGray code addressingGray codes
Rather than natural binary, the grid of Goodall's later tube was perforated to produce a glitch-free Gray code, and produced all bits simultaneously by using a fan beam instead of a scanning beam.
The "PCM tube" apparatus that Gray patented was made by Raymond W. Sears of Bell Labs, working with Gray and William M. Goodall, who credited Gray for the idea of the reflected binary code.

Ferranti-Packard

Ferranti CanadaFerranti ElectricPackard Electric
In 1949, for the Canadian Navy's DATAR system, Ferranti Canada built a working PCM radio system that was able to transmit digitized radar data over long distances.
By 1950, they had successfully developed a PCM-based radio system for passing digital data between ships, and the DRB started to become very interested.

ITT Inc.

ITTITT CorporationInternational Telephone and Telegraph
British engineer Alec Reeves, unaware of previous work, conceived the use of PCM for voice communication in 1937 while working for International Telephone and Telegraph in France.
Alec Reeves invented pulse-code modulation (PCM), upon which future digital voice communication was based, and Charles K. Kao pioneered the use of optical fiber, for which he was awarded the 2009 Nobel Prize in Physics.

Compact disc

CDCDsCD single
It is the standard form of digital audio in computers, compact discs, digital telephony and other digital audio applications.
The format is a two-channel 16-bit PCM encoding at a 44.1 kHz sampling rate per channel.

John R. Pierce

John Robinson PierceJohn PierceJ. J. Coupling
Another patent by the same title was filed by John R. Pierce in 1945, and issued in 1948:.
Pierce wrote on electronics and information theory, and developed jointly the concept of Pulse code modulation (PCM) with his Bell Labs colleagues Barney Oliver and Claude Shannon.

AES3

AES/EBUAES-EBU embedded timecodeAES
An AES3 signal can carry two channels of PCM audio over several transmission media including balanced lines, unbalanced lines, and optical fiber.

Compact Disc Digital Audio

Audio CDCDCD-DA
The standard also specifies the form of digital audio encoding: 2-channel signed 16-bit Linear PCM sampled at 44,100 Hz.

Bernard M. Oliver

Barney OliverBernard OliverBarnard M. Oliver
In the United States, the National Inventors Hall of Fame has honored Bernard M. Oliver

Integrated Services Digital Network

ISDN ISDNISDN30
By the 1990s, telecommunication networks such as the public switched telephone network (PSTN) had been largely digitized with very-large-scale integration (VLSI) CMOS PCM codec-filters, widely used in electronic switching systems for telephone exchanges, user-end modems and a wide range of digital transmission applications such as the integrated services digital network (ISDN), cordless telephones and cell phones.
ISDN uses the H.320 standard for audio coding and video coding, including audio codecs such as G.711 (PCM) and G.728 (CELP), and discrete cosine transform (DCT) video codecs such as H.261 and H.263.

Data transmission

data transferdigital communicationsdigital communication
By the 1990s, telecommunication networks such as the public switched telephone network (PSTN) had been largely digitized with very-large-scale integration (VLSI) CMOS PCM codec-filters, widely used in electronic switching systems for telephone exchanges, user-end modems and a wide range of digital transmission applications such as the integrated services digital network (ISDN), cordless telephones and cell phones.
It may also be an analog signal such as a phone call or a video signal, digitized into a bit-stream, for example, using pulse-code modulation (PCM) or more advanced source coding (analog-to-digital conversion and data compression) schemes.

HDMI

High-Definition Multimedia InterfaceHDMI 1.4HDMI 2.0
HDMI implements the EIA/CEA-861 standards, which define video formats and waveforms, transport of compressed and uncompressed LPCM audio, auxiliary data, and implementations of the VESA EDID.

DATAR

In 1949, for the Canadian Navy's DATAR system, Ferranti Canada built a working PCM radio system that was able to transmit digitized radar data over long distances.
By 1950 the small team at Ferranti Canada had built a working pulse-code modulation (PCM) radio system that was able to transmit digitized radar data over long distances.

S/PDIF

SPDIFIEC 61937digital audio output
S/PDIF can carry two channels of uncompressed PCM audio or compressed 5.1/7.1 surround sound (such as DTS audio codec); it cannot support lossless surround formats that require greater bandwidth.

David A. Hodges

Dave Hodges
The silicon-gate CMOS (complementary MOS) PCM codec-filter chip, developed by David A. Hodges and W.C. Black in 1980, has since been the industry standard for digital telephony.
He helped establish metal–oxide–semiconductor (MOS) devices as a practical technology for telephony applications, which led to the rapid development and wide adoption of pulse-code modulation (PCM) digital telephony.

AVCHD

AVCHD LiteNXCAMAVCCAM
For audio compression, it supports both Dolby AC-3 (Dolby Digital) and uncompressed linear PCM audio.

LaserDisc

LDlaser discLaserVision
Sound could be stored in either analog or digital format and in a variety of surround sound formats; NTSC discs could carry two analog audio tracks, plus two uncompressed PCM digital audio tracks, which were (EFM, CIRC, 16-bit and 44.056 kHz sample rate).

Audio Interchange File Format

AIFF.aiffAIF
The audio data in most AIFF files is uncompressed pulse-code modulation (PCM).