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Topic: Additive white Gaussian noise


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  Additive white Gaussian noise - Wikipedia, the free encyclopedia
In communications, the additive white Gaussian noise (AWGN) channel model is one in which the only impairment is the linear addition of wideband or white noise with a constant spectral density (expressed as watts per hertz of bandwidth) and a Gaussian distribution of amplitude.
Wideband Gaussian noise comes from many natural sources, such as the thermal vibrations of atoms in antennas (referred to as thermal noise or Johnson-Nyquist noise), shot noise, fl body radiation from the earth and other warm objects, and from celestial sources such as the sun.
The AWGN channel is a good model for many satellite and deep space communication links.
en.wikipedia.org /wiki/Additive_white_gaussian_noise   (274 words)

  
 White noise - Wikipedia, the free encyclopedia
White noise is the generalized mean-square derivative of the Wiener process or Brownian motion.
White noise has also been used in electronic music, where it is used either directly or as an input for a filter to create other types of noise signal.
White noise can be used to disorient individuals prior to interrogation and may be used as part of sensory deprivation techniques.
en.wikipedia.org /wiki/White_noise   (1599 words)

  
 Racal Instruments
Noise almost always couples to signals in an additive manner which is where the term Additive White Gaussian Noise (AWGN) comes from.
The Gaussian function for a normal distribution with the same mean value as the AWGN function is superimposed as a comparison.
Noise should be injected into the circuit in an additive manner because this is the way noise is normally coupled into circuits.
www.racalinst.com /apptech/ch10.html   (1112 words)

  
 Statistical noise: Facts and details from Encyclopedia Topic   (Site not responding. Last check: 2007-11-04)
(johnson noise or nyquist noise) is the noise generated by the equilibrium fluctuations of the...
Perlin noise is a function which uses interpolateinterpolation between a large number of pre-calculated gradient vectors to construct a value that varies pseudo-randomly...
Noise reduction is the process of removing noise from a signal....
www.absoluteastronomy.com /encyclopedia/s/st/statistical_noise.htm   (501 words)

  
 Gaussian noise -   (Site not responding. Last check: 2007-11-04)
Gaussian noise is noise that has a probability density function (pdf) of the Normal distribution (aka Gaussian distribution).
Gaussian noise is sometimes misunderstood to be white gaussian noise, but this is not so.
Strictly speaking, Gaussian noise only means noise with pdf of the Gaussian distribution, which says nothing to correlation of the noise in time.
psychcentral.com /psypsych/Gaussian_noise   (163 words)

  
 White noise -   (Site not responding. Last check: 2007-11-04)
It is often incorrectly assumed that Gaussian noise(ie noise with a Gaussian amplitude distribution - see normal distribution) is necessarily white noise.
There are also other "colors" of noise, the most commonly used being pink and brown.
White noise machines are sold as privacy enhancers and sleep aids.
psychcentral.com /psypsych/White_noise   (1845 words)

  
 white noise all on one page
E ewhite noise, eachwhite noise, egwhite noise, eightwhite noise, eightywhite noise, eitherwhite noise, elsewhite noise, elsewherewhite noise, endwhite noise, endingwhite noise, enoughwhite noise, etcwhite noise, evenwhite noise, everwhite noise, everywhite noise, everyonewhite noise, everythingwhite noise, everywherewhite noise, exceptwhite noise.
F fwhite noise, fewwhite noise, fiftywhite noise, firstwhite noise, fivewhite noise, forwhite noise, formerwhite noise, formerlywhite noise, fortywhite noise, foundwhite noise, white noise, fourwhite noise, fromwhite noise, furtherwhite noise.
F f, white noisefew, white noisefifty, white noisefirst, white noisefive, white noisefor, white noiseformer, white noiseformerly, white noiseforty, white noisefound, white noise, white noisefour, white noisefrom, white noisefurther.
seindex.fcpages.com /white-noise.html   (747 words)

  
 [No title]
The communications is modeled as an additive, white Gaussian noise channel with unit spectral amplitude.
Assuming the noise is white, design a binary signal set and the accompanying receiver which has the best possible performance.
The noise is found to not be white, but the power density spectrum is unknown.
cnx.rice.edu /content/m11301/1.3/source   (3642 words)

  
 Wireless Communications Test - October 1995 - Noise Com
Noise with power evenly distributed over all frequencies and amplitude distributed in Gaussian shape is called white Gaussian noise.
Crest factor is the ratio of peak noise voltage to the rms noise voltage.
Gaussian noise with an infinite crest factor will always produce a small but finite BER.
www.evaluationengineering.com /archive/articles/1095wire.htm   (1518 words)

  
 Transmission Through a Simulated Channel
It is typically assumed that the standard deviation of the noise varies with the rate at which bits are sent, increasing in proportion to the square root of the rate.
The Additive White Logistic Noise (AWLN) channel is similar to the AWGN channel, except that the noise comes from a logistic rather than a Gaussian distribution.
AWGN: The standard deviation of the Gaussian noise that is added to the encodings of the bits.
www.cs.toronto.edu /pub/radford/LDPC-2001-05-04/channel.html   (896 words)

  
 The Relevance of White Noise
White noise is also used to describe the incessant babble of radio, traffic, running rivers and brand placement.
Doubtless Dellilo perceives the significance of white noise increase.
The white noise is more then a background to them (to us?) it is a viscous pool in which they find themselves buoyant.
www.1w.net /nyu/wnoise.html   (2576 words)

  
 5533 fall 2004 final exam   (Site not responding. Last check: 2007-11-04)
Additive white gaussian noise is present with a two-sided power spectral density of 0.5*10
Consider the noise to be the energy of the aliased signal that gets past the ideal low pass filter, and the signal to be the energy of the unaliased baseband signal.
An equalizer is used at the output in an attempt to reverse the filtering of the narrow band channel.
www.okstate.edu /elec-engr/scheets/ecen5533/old_exams/5533_fall2004_final.html   (412 words)

  
 2. CODING AND MODULATION
The received signal is the sum of the transmitted signal and white Gaussian noise (noise occupying all frequencies).
A key observation from this figure is that there is not a significant loss in performance between what is possible in an additive white Gaussian noise channel and what is possible in a fading channel.
For the white Gaussian noise channel, low density parity check codes are within 0.01 dB of the fundamental limit when the block length is very large.
www.wtec.org /loyola/wireless/02_03.htm   (1874 words)

  
 Software tests real-world noise performance: News from Aeroflex
The addition of the AWGN feature transforms an RF signal generator into a noise generator.
IQCreator's AWGN feature is ideal for generating flexible and precise standalone AWGN power and repeatable signal-to-noise ratios (carrier noise or C/N).
Noise can also be added in-channel or in adjacent channels - on a single signal or among signals in a multi-carrier application.
www.electronicstalk.com /news/aof/aof129.html   (292 words)

  
 COLLEGE OF ELECTRICAL ENGINEERING   (Site not responding. Last check: 2007-11-04)
The purpose of the project is to investigate the effects that blurring, additive white Gaussian noise and coherent noise on various monochrome images.
Zero padding is used on the noise matrix to compensate for matrix inequalities between noise matrix and the blurred image matrix due to the convolution of the blur with the original image.
The Wiener filter is the MSE optimal stationary linear filter for images degraded by additive noise and blurring, requiring the assumption that the signal and noise processes are second-order wide sense stationary (WSS); in the sense of random processes [1].
www.personal.psu.edu /users/m/d/mde11/image_restoration.htm   (2845 words)

  
 Signal generation software adds AWGN feature: News from Aeroflex
IQCreator is a free Windows-based software application that enables a user to set up a wireless carrier modulation scheme and then create an arbitrary waveform file for use with the Aeroflex IFR 3410 and Aeroflex 3020 PXI series RF signal generators.
A precise and repeatable in-channel AWGN is especially important when determining a mobile receiver's sensitivity threshold.
Noise can also be added in-channel or in adjacent channels-on a single signal or among signals in a multi-carrier application.
www.qa-talk.com /news/aer/aer128.html   (300 words)

  
 does WGN(white Gaussian noise) imple zero mean?
WGN(white Gaussian noise process) imply zero mean or not...
The definition of a white noise process is that the PSD is 1
describe thermal noise in a resistor or whatnot as white noise, and
www.castalk.com /ftopic642.html   (3543 words)

  
 [No title]   (Site not responding. Last check: 2007-11-04)
The two models you may use in the Workshop are the Binary Symmetric Channel(BSC) and the Additive White Gaussian Noise channel(AWGN).
The AWGN channel models the distortion incurred by transmission over a lossy medium as the addition of a zero-mean Gaussian random value to each bit.
Likewise, for the AWGN channel, the parameters are the actual and estimate noise variance.
www.alantro.com /viterbi/doc/chanmodel.html   (250 words)

  
 Synthetic images with additive noise
This is because the noise variance is quite large compared to the edge strength; the grid filter is unable to localize the edge accurately.
In Figure 3.6, the Wiener filter leaves lots of noise behind; in Figure 3.7, it smoothes the noise at the expense of blurring the edges.
The Wiener filter smoothes out the noise in flat regions at the expense of the lines; this is most apparent in Figure 3.10.
www.osl.iu.edu /~tveldhui/papers/MAScThesis/node54.html   (605 words)

  
 A Brief History of Shot Noise
Shot noise was also investigated by Schottky in his 1918 paper on spontaneous current fluctuations in electric conductors [14].
His model included a noise process that consisted of samples of a Gaussian process where the sample times were Poisson distributed.
In 1991 Hero [6] approximated the likelihood ratio for observing a shot-noise process in the presence of additive white Gaussian noise.
homepages.cae.wisc.edu /~gubner/fpphist.shtml   (774 words)

  
 A Tutorial on Convolutional Coding with Viterbi Decoding
Convolutional encoding with Viterbi decoding is a FEC technique that is particularly suited to a channel in which the transmitted signal is corrupted mainly by additive white gaussian noise (AWGN).
You can think of AWGN as noise whose voltage distribution over time has characteristics that can be described using a Gaussian, or normal, statistical distribution, i.e.
Many radio channels are AWGN channels, but many, particularly terrestrial radio channels also have other impairments, such as multipath, selective fading, interference, and atmospheric (lightning) noise.
pweb.netcom.com /~chip.f/viterbi/tutorial.html   (2034 words)

  
 EE 459 Course Description
This is followed by a review of the theory of random processes including: power spectral density, multiple random processes, their transmission through linear systems and band-pass random processes.
This is followed by the theory of optimum signal detection; geometrical representation of signals and signal spaces, Gaussian processes, optimum receiver and equivalent signal sets are illustrated by several examples.
Elements of information theory and Shannon capacity theorem for an additive white Gaussian noise channel are discussed.
www.ee.psu.edu /acadaff/courses/ee459_description.html   (244 words)

  
 Combined Source-Channel Coding Schemes for Video Transmission over an Additive White Gaussian Noise Channel
Video transmitted over such a channel is subject to degradation due, in part, to additive white Gaussian noise (AWGN).
In this paper we develop a method of optimal bit allocation under the assumption that the distortion is additive and independent on a frame-by-frame basis.
A set of universal operational distortion-rate characteristics is developed which balances the tradeoff between source coding accuracy and channel error protection for a fixed overall transmission rate and provides the basis for the optimal bit allocation approach.
www.comsoc.org /sac/private/2000/jun/880_18sac06-bystrom.html   (640 words)

  
 Additive White Gaussian Noise Channel (AWGN)   (Site not responding. Last check: 2007-11-04)
In this channel model, an additive noise channel and both the modulator and the demodulator are included as parts of the channel except that the demodulator output is leaved unquantized.
According to Shannon's theorem on channel coding, the post-decoding bit-error probability can be obtained as small as possible as long as the coding rate R remains smaller than the channel capacity expressed in bit.
The Shannon limit correponding to 2-PAM signaling on a Gaussian channel is lower than the one corresponding to a binary symetric channel.
perso.enst-bretagne.fr /~kerbaol/util/digital_communications/channels/AWGN/AWGN.html   (512 words)

  
 ECE 4660: Lab 7-BPSK/QPSK Modulation and Demodulation
In the Gaussian Noise Generator, set the mean value to zero and the variance to a very small number (like 10^(-7)).
Generate a square-root Nyquist pulse such as a square-root RC pulse to serve as the impulse response of the transmitter pulse shaping filter that will be used in the I and Q branches.
Describe the effect of noise on the scatter plot and the eye diagram.
www.engineering.usu.edu /classes/ece/4660/lab7/lab7.html   (741 words)

  
 Anton Yen - UF Journal of Undergraduate Research Paper
Results are presented on the performance of the algorithm as a demodulator based on symbol error rates as well as its ability to provide channel quality estimates based on algorithm results such as the average distance to centroid.
The algorithm is useful as a demodulator because symbols that should be identical but vary due to noise are grouped together and assigned the same value.
It is interesting to note that the performance of the algorithm worsens as M increases due to the shorter distances between cluster centroids.
www.clas.ufl.edu /jur/200104/papers/paper_yen.html   (1928 words)

  
 blahut2 -- December94   (Site not responding. Last check: 2007-11-04)
It is true, I will agree with Dave, that in applications to the additive white gaussian noise channel, convolutional codes are much more widely used than block codes.
One might also make the point that the additive white gaussian noise channel occurs much less frequently than other kinds of channels.
I think that we should have something more to say about the problem of computing in noise with minimum energy per gate operation, but we never interact with those people and I think it is a legitimate area.
www.itsoc.org /publications/nltr/94_dec/blahut2.html   (952 words)

  
 [No title]
However, it is very useful as a conceptual entity and as an approximation to 'nearly white' processes which have finite bandwidth, but which are 'white' over all frequencies of practical interest.
This simply means a process which has a Gaussian pdf, a white PSD, and is linearly added to whatever signal we are analysing.
Conversely a nearly white Gaussian process which has been passed through a lowpass filter (see next section) will still have a Gaussian pdf (as it is a summation of Gaussians) but will no longer be white.
cnx.rice.edu /content/m11105/2.4/source   (410 words)

  
 Which footprints are best for additive noise?
Two techniques have been described for achieving large footprints without increasing the dimensionality of the grid substantially: foveated footprints (2.2) and hybrid filters (2.8).
To determine which of these approaches are better for removing additive noise, a variety of filters were trained on images of text with
Within current memory restrictions, it appears that hybrid grid filters are superior for removing substantial amounts of additive noise.
www.osl.iu.edu /~tveldhui/papers/MAScThesis/node53.html   (310 words)

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