how to remove incoherent but regularly-spaced noise?

Started by Anonymous in comp.dsp14 years ago 6 replies

We have images with regularly spaced noise. Specifically it occurs every 24 columns of the image, e.g. columns 24, 48, 72, 96, .... There is...

We have images with regularly spaced noise. Specifically it occurs every 24 columns of the image, e.g. columns 24, 48, 72, 96, .... There is also weaker noise beside this, so columns 23, 25, 47, 49, 71, 73 etc. are affected. So altogether 1/8 of the image is ruined. The noise is incoherent, but not exactly random: it is predominantly low frequency down the column. So the approach tried by...


How can I simulate non-Gaussian noise?

Started by jjdoc in comp.dsp13 years ago 5 replies

I'am studying robust methods for processing power electrical signals in non-Gaussian noise. I know the mostly used method is M-Estimator and...

I'am studying robust methods for processing power electrical signals in non-Gaussian noise. I know the mostly used method is M-Estimator and have already implemented an algorithm to analyze power harmonics. But how can I evaluate it and compare it with other non-robust methods. Besides impulsive noise, is there any other non-Gaussian noise? How can I simulate them? Thanks in advance!!!!!...


how to estimate the additive noise and get rid of additive noise in image?

Started by kiki in comp.dsp17 years ago 7 replies

Hi all, I obtained some pictures using camera. It looks to me there are some additive noise that was added to all image pixel components:...

Hi all, I obtained some pictures using camera. It looks to me there are some additive noise that was added to all image pixel components: from what I've observed, there are many small fluctuations/peaks/spikes of height 10-30, while the useful image region has values about 300. I am afraid that such noise has also been added to the useful image region, so the images have been univers...


adding 1/f noise to CDR input

Started by pedro904 in comp.dsp15 years ago 6 replies

Hello, I am trying to add 1/f noise to my CDR data input line which is generated using a Bernoulli binary block in simulink. However, when I...

Hello, I am trying to add 1/f noise to my CDR data input line which is generated using a Bernoulli binary block in simulink. However, when I use "Phase Noise" block in simulink, it generates error as phase noise expects complex input while Bernoulli output is real. Could anyone help me how to get around this problem? Or do you guys know any other method to add 1/f noise to input data. Thanks...


Adaptive noise cancellation

Started by derif in comp.dsp13 years ago 1 reply

I am working on a project where i am trying to remove noise from signal in real time. I have decided to use adaptive LMS algorithm. If x(n):...

I am working on a project where i am trying to remove noise from signal in real time. I have decided to use adaptive LMS algorithm. If x(n): input signal corrupted with noise y(n): output from filter; e(n): the error signal that controls the weights of filter Now do i need to generate another local noise source and feed it to the filter? Does the corrupted signal go directly into the...


spherical isotropic noise?

Started by Anonymous in comp.dsp15 years ago 14 replies

Dear all, Just read a paper and I am not sure what 'spherical isotroic noise' is? How can I simulate it in array processing? Should I treat it...

Dear all, Just read a paper and I am not sure what 'spherical isotroic noise' is? How can I simulate it in array processing? Should I treat it as a white noise in the near field of an array? Thanks, L. N.


Matched Filtering DC Noise Out

Started by Bret Cahill in comp.dsp12 years ago 12 replies

If the noise includes some DC it seems that a matched filter would treat it as a zero frequency "curve" and eliminate it in the convolution...

If the noise includes some DC it seems that a matched filter would treat it as a zero frequency "curve" and eliminate it in the convolution along with all the higher frequency noise. Bret Cahill


Does perfect white noise really exist?

Started by Ben in comp.dsp15 years ago 33 replies

A simple question: Based on the classical definition of "White Noise" (a random process which has zero autocorrelation, and a purely flat...

A simple question: Based on the classical definition of "White Noise" (a random process which has zero autocorrelation, and a purely flat PSD from -INF to +INF), measurement of white noise to determine these properties (rxx, PSD, mean, variance, skewness and kurtosis) poses a paradox: When we measure "pure white noise", we ise a band-limited measuring device (such as a spectrum analyzer), ...


LP analysis in AMR speech codec

Started by EC-AKD in comp.dsp17 years ago 4 replies

Hi, In the transcoding document provided by 3GPP standard for AMR speech codec, in the section LP analysis it is mentioned that...

Hi, In the transcoding document provided by 3GPP standard for AMR speech codec, in the section LP analysis it is mentioned that auto-corelation r(0) is multiplied by the white noise correction factor 1.0001 which is equivalent to adding a noise floor at -40dB. Could someone explain more about this. What is noise floor and why is it necessary to add the noise floor? Thanks and Regard...


noise removal

Started by babyish_angel in comp.dsp15 years ago 11 replies

hi everyone, does anyone of u knws how to remove noise in a graph?its kind of a new thing because normally we hear bout how to remove noise in...

hi everyone, does anyone of u knws how to remove noise in a graph?its kind of a new thing because normally we hear bout how to remove noise in an image. please let me knw if anyone of u knw.thnx.


Using cross-correlation function to recognize signal pattern

Started by Alexzabr in comp.dsp15 years ago

Hi. I have cetain sampled sequence out of non-stationary audio signal featured by certain noise pattern (which is also non-stationary in details...

Hi. I have cetain sampled sequence out of non-stationary audio signal featured by certain noise pattern (which is also non-stationary in details but is well defined in general). I intend to run numerous recordings featuring this noise, to separate the noise pieces ad process them in order to obtain some kind of averaged noise stamp (in time domain) and then to use it by cross-correlation with an ...


how to remove such kind of noise

Started by Tinwai in comp.dsp14 years ago 7 replies

Hi. If x(m) = s(m) + n(m), where n(m) is a noise whose power spectrum has random magnitudes at a certain frequency and its harmonies...

Hi. If x(m) = s(m) + n(m), where n(m) is a noise whose power spectrum has random magnitudes at a certain frequency and its harmonies (zero- valued otherwise). I.e. N(f) != 0 only at k*fo (say, fo = 60Hz, k = 1, 2, 3, ...). How can I remove such kind of noise? Thank you.


Variance of the noise in OFDM

Started by Richard_K in comp.dsp13 years ago

Hi, I am quite confused with the variance of the noise in the OFDM system. Should it be equal to N0 or N0/2? N0: Single sided noise power...

Hi, I am quite confused with the variance of the noise in the OFDM system. Should it be equal to N0 or N0/2? N0: Single sided noise power spectral density. Please help. Thanks.


noise reduction with long fft's

Started by apchar1 in comp.dsp6 years ago 12 replies

There's a statement in Smiths The Scientist and Engineer's Guide to Digital Signal Processing about the effect of fft length on noise. In arguing...

There's a statement in Smiths The Scientist and Engineer's Guide to Digital Signal Processing about the effect of fft length on noise. In arguing the virtues of averaging multiple short fft's instead of one long fft he says "Longer DFTs provide better frequency resolution, but the same noise level." But thats not true is it? The noise level of an fft rises with the sqrt(N). The signal grows wit...


I/Q modulation and phase noise sensitivity

Started by Peter Mairhofer in comp.dsp6 years ago 21 replies

Hi, I am observing something that is very counter-intuitive to me: I/Q modulation is very susceptible to phase noise? In an experiment I...

Hi, I am observing something that is very counter-intuitive to me: I/Q modulation is very susceptible to phase noise? In an experiment I plot "phase noise" vs. "SNR" and see a constant slope of ~20dB/dec. I use a real baseband signal, multiply it by cos(2*pi*fc*t) and then multiply it again by cos(2*pi*fc*t + phi(t)) where phi represents the phase noise. Finally, a simple image filter. I...


Unit pulse for White noise

Started by valtih1978 in comp.dsp10 years ago 16 replies

Do you know that there is one-to-one correspondence between frequency and time domain images of a function? Some people say that white noise...

Do you know that there is one-to-one correspondence between frequency and time domain images of a function? Some people say that white noise has white noise in frequency domain. However, we know that white noise has a frequency spectrum of constant "1". It is not a Guassian. The sum of all sines in freq domain is a Unit response! Why do they use all these complex random generators to pr...


PSK help

Started by Miso Soup Addict in comp.dsp17 years ago 3 replies

Hiya, I have a heavily noise contaminated source (12db sig/noise) which contains a BPSK signal. I know the frequency, but obviously not the...

Hiya, I have a heavily noise contaminated source (12db sig/noise) which contains a BPSK signal. I know the frequency, but obviously not the base phase or amplitude. Does anyone know any algorithms/code to decode this, and get the phase and ampltiude etc? I have other semi stationary noise frequencies near the one in question, if that helps selection at all. Any information, sugg...


Correlation and Expected value

Started by aarthis in comp.dsp14 years ago 4 replies

Hi, I have a doubt wrt Correlation and Expected value: 1. In many signal processing applications, there is a usage that the input signal...

Hi, I have a doubt wrt Correlation and Expected value: 1. In many signal processing applications, there is a usage that the input signal and noise are uncorrelated. This leads to E(Signal.Noise) = 0, that is, expected value of the product of signal and noise is taken as zero. How? It is not given that Signal and Noise are independent. I am only aware of the property of independent rando...


EVMDM642 problem in running examples

Started by arichard in comp.dsp15 years ago 1 reply

Dear Experts, I need your help in order to detect what i am possibly doing wrong. I try to run the examples that came with the board (just...

Dear Experts, I need your help in order to detect what i am possibly doing wrong. I try to run the examples that came with the board (just as it came), especially the video and video networking examples and the result is always the same: at the beginning the screen shows a color bar, and then when I try to run any of the examples the screen just becomes pink/grey. I am trying to run the e...


phase noise

Started by aamer in comp.dsp15 years ago 1 reply

Dear all, I am modelling phase noise for OFDM systems. At the receiver r=s*exp(j*phi)+w r= received signal s=transmitted...

Dear all, I am modelling phase noise for OFDM systems. At the receiver r=s*exp(j*phi)+w r= received signal s=transmitted signal phi=random phase w = AWGN noise I have studied in the literature that phase noise can be described as sampled version of wiener process, but for the purpose of analysis and simulations a discrete time random walk or weiner levy process is used. What exact...