## Forums Search for: White Noise

## Energy or Power?

inI read in the books that a periodic signal can have power but a random signal has energy. I am a bit confused by this as a white noise signal...

I read in the books that a periodic signal can have power but a random signal has energy. I am a bit confused by this as a white noise signal is random yet its variance is also the average power. Can a random signal have power or am I confused...By power here I mean instantaneous power V.I and not its integral which defines average power. thanks Tom

## DC Component of White Noise?

inWhite noise has a PSD = No/2 for all frequencies w. Does this hold true at w = 0? In this case does that mean that white noise must have a DC...

White noise has a PSD = No/2 for all frequencies w. Does this hold true at w = 0? In this case does that mean that white noise must have a DC component. What about zero mean white noise? Does this have: PSD(w) = No/2(1 - d(0)) where d(w) is the Kronecker Delta? I am simulating a baseband OFDM system and I want to add system noise at the appropriate level for a given SNR. Do I add noise on a...

## How do I calculate entropy?

inHow do I calculate entropy of a sampled signal of lenght N samples? I assume I need the PDF (probability density function) - can I use...

How do I calculate entropy of a sampled signal of lenght N samples? I assume I need the PDF (probability density function) - can I use the Periodogram P(f) is this is like the histogram and use H=-sum{=1 to N of } P(k)log(P(k)) does it have to be log base 2? I assume if I take the entropy of white noise what should be? Also I notice that log(P(f) are the cepstrum coefficients. ...

## pink noise

inHi ALL I need an algorithm to generate pink noise (a drop of 20dB/decade) from white noise (use in simulink) that is suitable for a frequency...

Hi ALL I need an algorithm to generate pink noise (a drop of 20dB/decade) from white noise (use in simulink) that is suitable for a frequency range of 1 to 100 Hz. Any suggestion is appreciated. Regards Karl

## Echo canceller

inWhite noise is a good, if not the best, training signal for the echo canceller. White noise has all the frequencies from 0 to fs/2. In...

White noise is a good, if not the best, training signal for the echo canceller. White noise has all the frequencies from 0 to fs/2. In telephony the range of usefull spectrum is roughly from 200Hz to 3400Hz (G712). So the output white noise will come back (echo) as a colored noise (band filtered white noise). So the echo canceller has to imitate this filtering. What is better for trainin...

## spectrum imbalance

inHi friends, I am developing an algorithm which is very sensitive to the shape of input signal spectrum. In ideal situation, singal spectrum...

Hi friends, I am developing an algorithm which is very sensitive to the shape of input signal spectrum. In ideal situation, singal spectrum should be symmectrical about zero frequency. however, the real signal captured from IF output is imbalanced. I guess there is something wrong in RF downconversion circuits. So, I feed a white noise to the RF input, and capture the IF output again, it s...

## In reality, how do people measure autocorrelation function?

inHi all, I heard tht white noise can be used to do system identification: finding the impulse response of an LTI system: generate a white...

Hi all, I heard tht white noise can be used to do system identification: finding the impulse response of an LTI system: generate a white noise x(t), and then input it to a system h(t), measure the output y(t), then find the R_yx(t), this is in fact the system impulse response h(t)... I understand this by showing it mathematically, yet I want to know what do people do in reality? How ...

## Complex Psudo-Noise Sequences

inI am trying to design a training sequence for a communications system. I originally had a real signal and I was using a periodic M-Sequence as...

I am trying to design a training sequence for a communications system. I originally had a real signal and I was using a periodic M-Sequence as the training signal (FYI an m-sequence is a special series of {+1,-1} which has an autocorrelation function which is almost a perfect spike: very like white noise). However, since I am doing bandpass communication, a real signal is double sideband, ...

## LP analysis in AMR speech codec

inHi, 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...

## How to transfer sensor function to state space model?

inIn my sensor implementation, I got a function: Y(t)=cos(theta(t))*( U(t) + W(t)+ C ) Where t denotes the sampling time, Y denotes the...

In my sensor implementation, I got a function: Y(t)=cos(theta(t))*( U(t) + W(t)+ C ) Where t denotes the sampling time, Y denotes the measured azimuth, 'theta' denotes the angle of the hilly road, U denotes the real azimuth(input), W denotes the zero mean Gaussian white noise, C denotes calibration error(constant). How to transfer this relation function to the state space model? T...

## Testing Digital Filter

inHello, I am using Linear feedback shift register(LFSR) to test Digital filter(DF) because LFSR generate white noise and has a flat...

Hello, I am using Linear feedback shift register(LFSR) to test Digital filter(DF) because LFSR generate white noise and has a flat like spectrum. Can anynody suggest when I pass white noise in DF, on what citeria should I judge the filter (Device Under Test) is pass or fail ?? my filter is 3rd order polyphase comb decimation filter with decimation factor of 256. ...

## white Noise

inIt is possible to describe white noise by a mathamatical function ??

It is possible to describe white noise by a mathamatical function ??

## Mixing correlated, band-limited Noise

inIf a band-limited white noise source is mixed with a non-delayed version of itself in a down-conversion process, is the noise cancelled? If the...

If a band-limited white noise source is mixed with a non-delayed version of itself in a down-conversion process, is the noise cancelled? If the noise is mixed with a version of itself, which is time delayed by greater than a 1/BW, is the noise power out of the mixer 2x one of the noise sources? I modelled this process in matalb and dont get the expected result. Thanks. This message was sent...

## Cross-Correlation Function of Band-limited Noise

inHi I'm looking at an instrument used in radio astronomy and hoped that you guys might be able to clarify something for me... 1) What is the...

Hi I'm looking at an instrument used in radio astronomy and hoped that you guys might be able to clarify something for me... 1) What is the cross-correlation function of two sets independent sets of band-limited white noise? 2) Peyton & Peebles says that if the two sets of band-limited noise are "even", Rxy(t) = 0 for all t because X and Y are orthogonal. How can you start talking about...

## Compare LMS NLMS

inHi I have some Problems with the NLMS. I have written a MATLAB skript to simulate the LMS and NLMS now I will compare these two...

Hi I have some Problems with the NLMS. I have written a MATLAB skript to simulate the LMS and NLMS now I will compare these two algorithms. Especially the convergence speed. Here I will compare the learning curves. Inputsignal: White noise (Matlab randn()) My major Problem is the choose of the different Parameters like step size and so on. The coefficient-update: w(n+1)=w(n)+mu(n)*e...

## Aliasing and Sampling Prog question

inI want to show aliasing and sampling graphically with spectra by using LabVIEW (or similar).Here is what I am doing I have a ficticious...

I want to show aliasing and sampling graphically with spectra by using LabVIEW (or similar).Here is what I am doing I have a ficticious sampling freq which is my 'analogue' signal - lets say I make it 500MHz. I then pass white noise through a narrowband filter centred at say 10.7MHz bandwidth 200kHz. I take the FFT and see the spectrum and its negative image - no problem. I add a sine w...

## SNR in Simulink

inPhil Newman Aug 10, 10:05 am show options I have a pure tone sine-wave signal of amplitude 1 and frequency 1. I have additional white...

Phil Newman Aug 10, 10:05 am show options I have a pure tone sine-wave signal of amplitude 1 and frequency 1. I have additional white noise signal added to this pure tone signal. The white noise is specified as Noise Power, and simulink defines this as the height of the Power Spectral Density of the white noise. (in this case it is set to 0.02) Can anyone help me with calcul...

## Removing White Noise

inHey everyone, I have an audio application, and I'm trying to do some pre/post processing to improve the sound quality. I put in an adaptive...

Hey everyone, I have an audio application, and I'm trying to do some pre/post processing to improve the sound quality. I put in an adaptive filter to try and remove structured noise, but I'd like to remove white/pink noise from the signal somehow.. I've been looking at wavelet techniques, or whatever else I can find. Can anyone recommend a good way to reduce white noise from audio/ A...

## Integral of White noise

inWhat happens when you integrate white noise over time? Can anyone give a mathematical representation of this thing?

What happens when you integrate white noise over time? Can anyone give a mathematical representation of this thing?

## regarding white noise

inhi, I am new to these group. I want to know why white noise floor is added to the autocorrelation function in the lpc analysis. what is...

hi, I am new to these group. I want to know why white noise floor is added to the autocorrelation function in the lpc analysis. what is the difference between lsp and lsf thanks in advance venugopal