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Encyclopedia > Signal noise
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In science, and especially in physics and telecommunication, noise is fluctuations in and the addition of external factors to the stream of target information (signal) being received at a detector. In communications, it may be deliberate as for instance jamming of a radio or TV signal, but in most cases it is assumed to be merely undesired interference with intended operations. Natural and deliberate noise sources can provide both or either of random interference or patterned interference. Only the latter can be cancelled effectively in analog systems; however, digital systems are usually constructed in such a way that their quantized signals can be reconstructed perfectly, as long as the noise level remains below a defined maximum, which varies from application to application. // What is science? There are different theories of what science is. ... Since antiquity, people have tried to understand the behavior of matter: why unsupported objects drop to the ground, why different materials have different properties, and so forth. ... BlackBerry 7100t Telecommunication refers to communication over long distances. ... In information theory, a signal is a flow of information. ... The term Jamming can refer to several things: Jamming as an electronic warfare (EW) - a technique to limit the effectiveness of an opponents communications and/or detection equipment, like Radio Jamming and Radar Jamming E-Mail Jamming- used by electronic political activists or hackers to disable e-mail systems... In ordinary language, the word random is used to express apparent lack of purpose or cause. ... An analog or analogue signal is any continuously variable signal. ... This article is being considered for deletion in accordance with Wikipedias deletion policy. ... Generally, quantization is the state of being constrained to a set of discrete values, rather than varying continuously. ...


More specifically, in physics, the term noise has the following meanings:

  1. An undesired disturbance within the frequency band of interest; the summation of unwanted or disturbing energy introduced into a communications system from man-made and natural sources.
  2. A disturbance that affects a signal and that may distort the information carried by the signal.
  3. Random variations of one or more characteristics of any entity such as voltage, current, or data.
  4. A random signal of known statistical properties of amplitude, distribution, and spectral density.
  5. Loosely, any disturbance tending to interfere with the normal operation of a device or system.

Noise and what can be done about it has long been studied. Claude Shannon established information theory and in so doing clarified the essential nature of noise and the limits it places on the operation of electronic equipment. Sine waves of various frequencies; the lower waves have higher frequencies than those above. ... Band may mean: A musical band A band (electronics) is a range of frequencies or wavelengths between two given limits In anthropology, a band society A Rubber band In solid-state physics, an energy band The Band, a particular musical band See also: bandana This is a disambiguation page — a... In telecommunication, a communications system is a collection of individual communications networks, transmission systems, relay stations, tributary stations, and data terminal equipment (DTE) usually capable of interconnection and interoperation to form an integrated whole. ... Signaling, or signal, may mean: Look up signal on Wiktionary, the free dictionary. ... Jump to: navigation, search Information is a word which has many different meanings in everyday usage and in specialized contexts, but as a rule, the concept is closely related to others such as data, instruction, knowledge, meaning, communication, representation, and mental stimulus. ... Jump to: navigation, search DATA (Debt, AIDS, Trade, Africa) was established in 2002 by Bono (Paul Hewson) of the Rock band U2, and Bobby Shiver, along with activists from the Jubilee 2000 Drop the Debt Campaign, as an organisaton focused on Justice, not charity. ... The spectral density of a signal is a way of measuring the strength of the different frequencies that form the signal. ... The word operation can mean any of several things: The method, act, process, or effect of using a device or system. ... Claude Elwood Shannon (April 30, 1916 _ February 24, 2001) has been called the father of information theory, and was the founder of practical digital circuit design theory. ... Information theory is the mathematical theory of data communication and storage founded in 1948 by Claude E. Shannon. ...


In some cases a little noise may be considered advantageous, allowing a dithered representation of signals below the minimum strength, or between two quantization levels. This is especially true for signals intended for human appreciation, since the brain seems to expect signals to contain a degree of noise. See, for example [1] Jump to: navigation, search Dither is a form of noise, or erroneous signal or data which is added to sample data for the purpose of minimizing quantization error. ...


See also

Some sections copied from Federal Standard 1037C and from MIL-STD-188 Shot noise consists of random fluctuations of the electric current in an electrical conductor, which are caused by the fact that the current is carried by discrete charges (electrons). ... Pink noise, also known as 1/f noise, is a signal or process with a frequency spectrum such that the spectral energy density is proportional to the reciprocal of the frequency. ... Jump to: navigation, search Four thousandths of a second of white noise White noise (Sample â–¶(?)) is a random signal (or process) with a flat power spectral density. ... Johnson-Nyquist noise (sometimes thermal noise, Johnson noise or Nyquist noise) is the noise generated by the equilibrium fluctuations of the electric current inside an electrical conductor, which happens without any applied voltage, due to the random thermal motion of the charge carriers (the electrons). ... Signal-to-noise ratio (often abbreviated SNR or S/N) is meaningful both in the context of information theory and, informally, for Usenet or other newsgroup-like services. ... In telecommunication, noise level is the noise power, usually relative to a reference. ... In telecommunication, the term noise power has the following meanings: 1. ... Noise-equivalent power (NEP) is the radiant power that produces a signal-to-noise ratio of unity at the output of a given optical detector at a given data-signaling rate or modulation frequency, operating wavelength, and effective noise bandwidth. ... In an oscillator, phase noise is rapid, short-term, random fluctuations in the phase of a wave, caused by time domain instabilities. ... Johnson-Nyquist noise (sometimes thermal noise, Johnson noise or Nyquist noise) is the noise generated by the equilibrium fluctuations of the electric current inside an electrical conductor, which happens without any applied voltage, due to the random thermal motion of the charge carriers (the electrons). ... This is a list of noise topics, by Wikipedia page. ... The designer of a system for sound reproduction needs to be able to measure the systems performance in a number of areas. ... There are many forms of noise with various frequency characteristics that are classified by color. Some have well-defined technical definitions, while others are colloquial or jokes. ... Jump to: navigation, search // Quantum 1/f noise Quantum 1/f noise is an intrinsic part of Quantum Mechanics. ... Federal Standard 1037C entitled Telecommunications: Glossary of Telecommunication Terms is a U.S. Federal Standard, issued by the General Services Administration pursuant to the Federal Property and Administrative Services Act of 1949, as amended. ... MIL-STD-188 is a series of U.S. military standards relating to telecommunications. ...


  Results from FactBites:
 
Signal-to-noise ratio - Wikipedia, the free encyclopedia (1077 words)
With an interferometric system, however, where interest lies in the signal from one arm only, the field of the electromagnetic wave is proportional to the voltage (assuming that the intensity in the second, the reference arm is constant).
In this case the noise is the error signal caused by the quantization of the signal, taking place in the analog-to-digital conversion.
Assuming a full-scale sine wave signal, the quantization noise approximates a sawtooth wave with peak-to-peak amplitude of one quantization level.
Signal noise - Wikipedia, the free encyclopedia (399 words)
In science, and especially in physics and telecommunication, noise is fluctuations in and the addition of external factors to the stream of target information (signal) being received at a detector.
In communications, it may be deliberate as for instance jamming of a radio or TV signal, but in most cases it is assumed to be merely undesired interference with intended operations.
In some cases a little noise may be considered advantageous, allowing a dithered representation of signals below the minimum strength, or between two quantization levels.
  More results at FactBites »

 
 

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