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Compander
In telecommunication and signal processing, companding (occasionally called compansion) is a method of mitigating the detrimental effects of a channel with limited dynamic range. The name is a portmanteau of the words compressing and expanding, which are the functions of a compander at the transmitting and receiving end respectively. The use of companding allows signals with a large dynamic range to be transmitted over facilities that have a smaller dynamic range capability. Companding is employed in telephony and other audio applications such as professional wireless microphones and analog recording. How it works The dynamic range of a signal is compressed before transmission and is expanded to the original value at the receiver. The electronic circuit that does this is called a compander and works by compressing or expanding the dynamic range of an analog electronic signal such as sound recorded by a microphone. One variety is a triplet of amplifiers: a logarithmic amplifier, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Noise Reduction Scheme
Noise reduction is the process of removing noise from a signal. Noise reduction techniques exist for audio and images. Noise reduction algorithms may distort the signal to some degree. Noise rejection is the ability of a circuit to isolate an undesired signal component from the desired signal component, as with common-mode rejection ratio. All signal processing devices, both analog and digital, have traits that make them susceptible to noise. Noise can be random with an even frequency distribution (white noise), or frequency-dependent noise introduced by a device's mechanism or signal processing algorithms. In electronic systems, a major type of noise is ''hiss'' created by random electron motion due to thermal agitation. These agitated electrons rapidly add and subtract from the output signal and thus create detectable noise. In the case of photographic film and magnetic tape, noise (both visible and audible) is introduced due to the grain structure of the medium. In photograp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Demo Of Mu-law Compression
Demo, usually short for demonstration, may refer to: Music and film *Demo (music), a song typically recorded for reference rather than release * ''Demo'' (Behind Crimson Eyes), a 2004 recording by the band Behind Crimson Eyes * ''Demo'' (Deafheaven album), a 2010 EP by Deafheaven * ''Demo'' (The Flat liners Album), a 2002 album by the band The Flatliners * ''Demo'' (Miss May I album), a 2008 recording by the metalcore band Miss May I *"Demo", a 1990 single by Die Krupps * "Demo" (P-Model song), a 1979 recording by songwriters Susumu Hirasawa and Yasumi Tanaka *''Demo (Skinless)'', a 1994 recording by the band Skinless * ''Demo 2004'' (Year of No Light album), a 2004 recording by Year of No Light *'' Demo #2'', an unreleased recording by Neutral Milk Hotel *''Demo'', 2008 debut EP by Yuna Computing and technology *Demo (computer programming), a multimedia spectacle of programming skill * The Demo, a computer demonstration in 1968, sometimes called "the mother of all demos" * DEM ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
T-carrier
The T-carrier is a member of the series of carrier systems developed by AT&T Bell Laboratories for digital transmission of multiplexed telephone calls. The first version, the Transmission System 1 (T1), was introduced in 1962 in the Bell System, and could transmit up to 24 telephone calls simultaneously over a single transmission line of copper wire. Subsequent specifications carried multiples of the basic T1 (1.544 Mbit/s) data rates, such as T2 (6.312 Mbit/s) with 96 channels, T3 (44.736 Mbit/s) with 672 channels, and others. Although a ''T2'' was defined as part of AT&T's T-carrier system, which defined five levels, T1 through T5, only the T1 and T3 were commonly in use.1999 ad: On the left, in an aisle seat, a man who very much "filled" his airline seat while on the right side of the aisle is a height-challenged man whose shoe toes barely reach the floor Transmission System 1 The T-carrier is a hardware specification for carrying multiple time-divis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Digital Synthesizer
A digital synthesizer is a synthesizer that uses digital signal processing (DSP) techniques to make musical sounds. This in contrast to older analog synthesizers, which produce music using analog electronics, and samplers, which play back digital recordings of acoustic, electric, or electronic instruments. Some digital synthesizers emulate analog synthesizers; others include sampling capability in addition to digital synthesis. History The very earliest digital synthesis experiments were made with computers, as part of academic research into sound generation. In 1973, the Japanese company Yamaha licensed the algorithms for frequency modulation synthesis (FM synthesis) from John Chowning, who had experimented with it at Stanford University since 1971. Yamaha's engineers began adapting Chowning's algorithm for use in a commercial digital synthesizer, adding improvements such as the "key scaling" method to avoid the introduction of distortion that normally occurred in analog sys ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Korg
, founded as Keio Electronic Laboratories, is a Japanese multinational corporation that manufactures electronic musical instruments, audio processors and guitar pedals, recording equipment, and electronic tuners. Under the Vox brand name, they also manufacture guitar amplifiers and electric guitars. History Korg was founded in 1962 in Tokyo by Tsutomu Kato and Tadashi Osanai as ''Keio Gijutsu Kenkyujo Ltd.''. It later became because its offices were located near the Keio train line in Tokyo and Keio can be formed by combining the first letters of Kato and Osanai. Before founding the company, Kato ran a nightclub. Osanai, a Tokyo University graduate and noted accordionist, regularly performed at Kato's club accompanied by a Wurlitzer Sideman rhythm machine. Dissatisfied with the rhythm machine, Osanai convinced Kato to finance his efforts to build a better one.Julian Colbeck, Keyfax Omnibus Edition, MixBooks, 1996, p. 52. The company's first product was an electro- ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Yamaha Corporation
is a Japanese multinational corporation and conglomerate with a very wide range of products and services. It is one of the constituents of Nikkei 225 and is the world's largest musical instrument manufacturing company. The former motorcycle division was established in 1955 as Yamaha Motor Co., Ltd., which started as an affiliated company but later became independent, although Yamaha Corporation is still a major shareholder. History Nippon Gakki Co. Ltd. (currently Yamaha Corporation) was established in 1887 as a reed organ manufacturer by Torakusu Yamaha (山葉寅楠) in Hamamatsu, Shizuoka Prefecture and was incorporated on 12 October 1897. In 1900, the company started the production of pianos. The first piano to be made in Japan was an upright built in 1900 by Torakusu Yamaha, founder of Nippon Gakki Co., Ltd. — later renamed Yamaha Corporation. The company's origins as a musical instrument manufacturer are still reflected today in the group's logo—a trio of interloc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Roland Corporation
is a Japanese manufacturer of electronic musical instruments, electronic equipment, and software. It was founded by Ikutaro Kakehashi in Osaka on 18 April 1972. In 2005, its headquarters relocated to Hamamatsu in Shizuoka Prefecture. It has factories in Malaysia, Taiwan, Japan, and the United States. As of 31 March 2010, it employed 2,699 people. In 2014, it was subject to a management buyout by its CEO, Junichi Miki, supported by Taiyo Pacific Partners. Roland has manufactured numerous instruments that have had lasting impacts on music, such as the Juno-106 synthesizer, TB-303 bass synthesizer, and TR-808 and TR-909 drum machines. It was also instrumental in the development of MIDI, a standardized means of synchronizing electronic instruments manufactured by different companies. In 2016, ''Fact'' wrote that Roland had arguably had more influence on electronic music than any other company. History 1970s Having created Ace Electronic Industries Inc in 1960, Ikutaro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SIGSALY
SIGSALY (also known as the X System, Project X, Ciphony I, and the Green Hornet) was a secure speech system used in World War II for the highest-level Allied communications. It pioneered a number of digital communications concepts, including the first transmission of speech using pulse-code modulation. The name SIGSALY was not an acronym, but a cover name that resembled an acronym—the SIG part was common in Army Signal Corps names (e.g., SIGABA). The prototype was called the "Green Hornet" after the radio show ''The Green Hornet'', because it sounded like a buzzing hornet, resembling the show's theme tune, to anyone trying to eavesdrop on the conversation. Development At the time of its inception, long-distance telephone communications were broadcast using the "A-3" voice scrambler developed by Western Electric. The Germans had a listening station on the Dutch coast which could intercept and break A-3 traffic. [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
American Telephone & Telegraph
AT&T Corporation, originally the American Telephone and Telegraph Company, is the subsidiary of AT&T Inc. that provides voice, video, data, and Internet telecommunications and professional services to businesses, consumers, and government agencies. During the Bell System's long history, AT&T was at times the world's largest telephone company, the world's largest cable television operator, and a regulated monopoly. At its peak in the 1950s and 1960s, it employed one million people and its revenue ranged between US$3 billion in 1950 ($ in present-day terms) and $12 billion in 1966 ($ in present-day terms). In 2005, AT&T was purchased by Baby Bell and former subsidiary SBC Communications for more than $16 billion ($ in present-day terms). SBC then changed its name to AT&T Inc. Today, AT&T Corporation continues to exist as the long distance subsidiary of AT&T Inc., and its name occasionally shows up in AT&T press releases. Buildings with AT&T logo * AT&T Huro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Audio Data Compression
In information theory, data compression, source coding, or bit-rate reduction is the process of encoding information using fewer bits than the original representation. Any particular compression is either lossy or lossless. Lossless compression reduces bits by identifying and eliminating statistical redundancy. No information is lost in lossless compression. Lossy compression reduces bits by removing unnecessary or less important information. Typically, a device that performs data compression is referred to as an encoder, and one that performs the reversal of the process (decompression) as a decoder. The process of reducing the size of a data file is often referred to as data compression. In the context of data transmission, it is called source coding; encoding done at the source of the data before it is stored or transmitted. Source coding should not be confused with channel coding, for error detection and correction or line coding, the means for mapping data onto a signa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Au File Format
The Au file format is a simple audio file format introduced by Sun Microsystems. The format was common on NeXT systems and on early Web pages. Originally it was headerless, being simply 8-bit μ-law-encoded data at an 8000 Hz sample rate. Hardware from other vendors often used sample rates as high as 8192 Hz, often integer multiples of video clock signal frequencies. Newer files have a header that consists of six unsigned 32-bit words, an optional information chunk which is always of non-zero size, and then the data (in big endian format). Although the format now supports many audio encoding formats, it remains associated with the μ-law logarithmic encoding. This encoding was native to the SPARCstation 1 hardware, where SunOS exposed the encoding to application programs through the /dev/audio interface. This encoding and interface became a de facto standard for Unix sound. New format All fields are stored in big-endian format, including the sample data. The type ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pulse-code Modulation
Pulse-code modulation (PCM) is a method used to digitally represent sampled analog signals. It is the standard form of digital audio in computers, compact discs, digital telephony and other digital audio applications. In a PCM stream, the amplitude of the analog signal is sampled regularly at uniform intervals, and each sample is quantized to the nearest value within a range of digital steps. Linear pulse-code modulation (LPCM) is a specific type of PCM in which the quantization levels are linearly uniform. This is in contrast to PCM encodings in which quantization levels vary as a function of amplitude (as with the A-law algorithm or the μ-law algorithm). Though ''PCM'' is a more general term, it is often used to describe data encoded as LPCM. 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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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