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Signal Compression
Signal compression is the use of various techniques to increase the quality or quantity of signal parameters transmitted through a given telecommunications channel. Types of signal compression include: * Bandwidth compression * Data compression *Dynamic range compression Dynamic range compression (DRC) or simply compression is an audio signal processing operation that reduces the volume of loud sounds or amplifies quiet sounds, thus reducing or ''compressing'' an audio signal's dynamic range. Compression is c ... * Gain compression * Image compression * Lossy compression * One-way compression function {{sia Compression Telecommunications techniques he:דחיסת אותות ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Bandwidth Compression
In telecommunications, the term bandwidth compression has the following meanings: *The reduction of the Bandwidth (computing), bandwidth needed to transmit a given amount of data in a given time. *The reduction of the time needed to transmit a given amount of data in a given bandwidth. Bandwidth compression implies a reduction in normal bandwidth of an information-carrying signal (information theory), signal without reducing the information content of the signal. This can be accomplished with lossless data compression techniques. For more information read the Modem#Speeds, Increasing speeds section in the Modem article. Bandwidth Compression is a core feature of WAN Optimization appliances to improve bandwidth efficiency. Bandwidth compression plays a critical role in modern communication systems, particularly as demand for data-intensive services continues to increase. It is not only a means to optimize transmission efficiency but also a strategic response to the limitations of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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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 is 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 sig ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Dynamic Range Compression
Dynamic range compression (DRC) or simply compression is an audio signal processing operation that reduces the volume of loud sounds or amplifies quiet sounds, thus reducing or ''compressing'' an audio signal's dynamic range. Compression is commonly used in sound recording and reproduction, broadcasting, sound reinforcement system, live sound reinforcement and some instrument amplifiers. A dedicated electronic hardware unit or audio software that applies compression is called a compressor. In the 2000s, compressors became available as software plugins that run in digital audio workstation software. In recorded and live music, compression parameters may be adjusted to change the way they affect sounds. Compression and limiting are identical in process but different in degree and perceived effect. A limiter is a compressor with a high #Ratio, ratio and, generally, a short #Attack and release, attack time. Compression is used to improve performance and clarity in public address ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Gain Compression
Gain compression is a reduction in ''differential'' or ''slope'' gain caused by nonlinearity of the transfer function of an amplifying device for large-signal inputs. Overview When overdriving an amplifier beyond its the linear range, gain compression will occur due to nonlinear circuit characteristics. The output of large amplitude inputs will be less than expected than using the small signals gain of the amplifier, such that an increase in input will not be matched by a proportional increase in output. Gain compression is the difference between the ideal linear power transfer curve and the real circuit's power transfer curve. An important gain compression parameter is the OP1dB, which is the power input that results in a 1 dB compression of the output power (OP), corresponding to a gain ratio of 10 = 79.4%. Harmonic distortion results from nonlinear transfer curves. And once an amplifier's maximum amplitude is reached, signals will be clipped, resulting in even ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Image Compression
Image compression is a type of data compression applied to digital images, to reduce their cost for computer data storage, storage or data transmission, transmission. Algorithms may take advantage of visual perception and the statistical properties of image data to provide superior results compared with generic data compression methods which are used for other digital data. Lossy and lossless image compression Image compression may be lossy compression, lossy or lossless compression, lossless. Lossless compression is preferred for archival purposes and often for medical imaging, technical drawings, clip art, or comics. Lossy compression methods, especially when used at low bit rates, introduce compression artifacts. Lossy methods are especially suitable for natural images such as photographs in applications where minor (sometimes imperceptible) loss of fidelity is acceptable to achieve a substantial reduction in bit rate. Lossy compression that produces negligible differences ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Lossy Compression
In information technology, lossy compression or irreversible compression is the class of data compression methods that uses inexact approximations and partial data discarding to represent the content. These techniques are used to reduce data size for storing, handling, and transmitting content. Higher degrees of approximation create coarser images as more details are removed. This is opposed to lossless data compression (reversible data compression) which does not degrade the data. The amount of data reduction possible using lossy compression is much higher than using lossless techniques. Well-designed lossy compression technology often reduces file sizes significantly before degradation is noticed by the end-user. Even when noticeable by the user, further data reduction may be desirable (e.g., for real-time communication or to reduce transmission times or storage needs). The most widely used lossy compression algorithm is the discrete cosine transform (DCT), first published by N ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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One-way Compression Function
In cryptography, a one-way compression function is a function that transforms two fixed-length inputs into a fixed-length output.Handbook of Applied Cryptography by Alfred J. Menezes, Paul C. van Oorschot, Scott A. Vanstone. Fifth Printing (August 2001) page 328. The transformation is one-way function, "one-way", meaning that it is difficult given a particular output to compute inputs which compress to that output. One-way compression functions are not related to conventional data compression algorithms, which instead can be inverted exactly (lossless compression) or approximately (lossy compression) to the original data. One-way compression functions are for instance used in the Merkle–Damgård construction inside cryptographic hash functions. One-way compression functions are often built from block ciphers. Some methods to turn any normal block cipher into a one-way compression function are Davies–Meyer, Matyas–Meyer–Oseas, Miyaguchi–Preneel (single-block-length compr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Signal Processing
Signal processing is an electrical engineering subfield that focuses on analyzing, modifying and synthesizing ''signals'', such as audio signal processing, sound, image processing, images, Scalar potential, potential fields, Seismic tomography, seismic signals, Altimeter, altimetry processing, and scientific measurements. Signal processing techniques are used to optimize transmissions, Data storage, digital storage efficiency, correcting distorted signals, improve subjective video quality, and to detect or pinpoint components of interest in a measured signal. History According to Alan V. Oppenheim and Ronald W. Schafer, the principles of signal processing can be found in the classical numerical analysis techniques of the 17th century. They further state that the digital refinement of these techniques can be found in the digital control systems of the 1940s and 1950s. In 1948, Claude Shannon wrote the influential paper "A Mathematical Theory of Communication" which was publis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Telecommunications Techniques
Telecommunication, often used in its plural form or abbreviated as telecom, is the transmission of information over a distance using electronic means, typically through cables, radio waves, or other communication technologies. These means of transmission may be divided into communication channels for multiplexing, allowing for a single medium to transmit several concurrent communication sessions. Long-distance technologies invented during the 20th and 21st centuries generally use electric power, and include the telegraph, telephone, television, and radio. Early telecommunication networks used metal wires as the medium for transmitting signals. These networks were used for telegraphy and telephony for many decades. In the first decade of the 20th century, a revolution in wireless communication began with breakthroughs including those made in radio communications by Guglielmo Marconi, who won the 1909 Nobel Prize in Physics. Other early pioneers in electrical and electronic t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |