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Discussion Groups > Autocorrelation

Comp.dsp is a worldwide Usenet news group that is used to discuss various aspects of digital signal processing.

We found 515 threads matching "autocorrelation"

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The most relevant threads are listed first

autocorrelation function C code for full signal
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Qiaoke_lily - 2007-12-13 08:12:00
Hi: im interested in finding autocorrelation function for a whole signal instead of a frame only of a signal. i have been refered to a post in year06 (Autocorrelation function, Java or C code) regarding the autocorrelation for a frame of a signal, and i tried to modify the C code for finding the ...autocorrelation function C code for full signal

construction of a signal given its autocorrelation sequence
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manolis - 2008-02-25 10:38:00
Hello! My question relates to DSP theory: suppose that i have an autocorrelation sequence in a closed form formula. This autocorrelation sequence may correspond to many different signals. My question is how can i construct a signal whose autocorrelation is the given one? Anyone expert? ...construction of a signal given its autocorrelation sequence

Periodic and aperiodic autocorrelation
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Treviasty - 2010-06-14 07:36:00
Hello ! I'm starting experiments with compressed pulse radar and I have to choose the best signal to transmit - low autocorrelation sidelobes, good ambiguity function etc. . But there is one thing I can't understand - why there are so many publications and researches about sequences with good per...Periodic and aperiodic autocorrelation

About autocorrelation matrix of a Periodic correlation function
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ryujin_ssdt - 2007-11-01 06:01:00
What properties an autocorrelation matrix would have if the corresponding autocorrelation function is periodic in time with certain integer period T?? I am interested in obtaining something like a cyclic autocorrelation matrix of a cyclostationary process but have no idea where to start from. ...About autocorrelation matrix of a Periodic correlation function

autocorrelation matrix
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matque - 2007-03-13 12:33:00
I'm trying to copmute the autocorrelation matrix of array outputs and suspect i may be doing something wrong. I'm confident that i'm getting the right result for vectors but when my signal is a matrix it all goes wrong. Looking at the examples below can anyone say if they are correct? e.g. If ...autocorrelation matrix

Autocorrelation Tutorial/notes
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jpchibole - 2009-03-09 06:44:00
Hey guys I am studying DSP on my own and would like anyone out there who has good notes on Autocorrelation from the very basic to post them for me to use. Second I hope from your notes, I will be able to understand variance and be able to maybe construct an autocorrelation matrix of order 4 and fin...Autocorrelation Tutorial/notes

Random numbers with exacty zero autocorrelation
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jeroen_trip - 2006-09-04 09:43:00
Hi all, I'm trying to simulate a small sample, say 15 numbers, of white noise. But due to chance, the autocorrelation is not exactly 0. Of course the standard deviation is also not exacty 1 but I can fix that. Is there transformation to get rid of the unwanted autocorrelation?? Many thanks, ...Random numbers with exacty zero autocorrelation

autocorrelation of a downsampled signal
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Thierry - 2009-07-12 20:25:00
Hi Guys, forgive me but it has been 10 years since i took a course in signal processing. i am doing some simulations and i need the expression of the autocorrelation (Rx') of a signal after downsampling using the autocorrelation (Rx) of the unsampled signal. I think it should be :Rx'(n)=(1/M)...autocorrelation of a downsampled signal

Autocorrelation
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OZ - 2005-07-18 08:35:00
Hi, I am using an autocorrelation function to calculate the period of a signal. It is a signal which is periodic. My problem is that there are some parts with big amplitudes and some part with small amplitudes. The disadvantage of the autocorrelation is that the big amplitudes are dominant a...Autocorrelation

Basics of Spectral Density and Autocorrelation Function
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lebann - 2005-07-27 21:48:00
Hi, I am trying to grasp the basics of autocorrelation and PSD. I dont have a strong background on DSP, so any help will be appreciated. Here are my questions: (1) why is the PSD, which is given by : PSD(f)=4*Integral[cos(2*pi*f*t)*Autocorrelation from -inf, +inf] is VALID ONLY for freq...Basics of Spectral Density and Autocorrelation Function

Autocorrelation function, Java or C code
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Thomas Magma - 2006-06-16 14:09:00
Does anyone have any optimized Java or C code for an autocorrelation function. It is my first time needing to do autocorrelation and it seems straight forward enough to be able to write the code myself, but due to the amount of iterations it would be wise to ask for code that already has it's ...Autocorrelation function, Java or C code

autocorrelation
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John McDermick - 2011-01-03 18:40:00
Is there a signal x for which the autocorrelation sequence r would be a 'flat' line ? For example r = [0.5 0.5 0.5 0.5 0.5 0.5] My guess is no. Can somebody confirm? ...autocorrelation

nonstationary autocorrelation but stationary PSD
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fisico32 - 2010-05-17 18:18:00
Hello Forum the nonstationary autocorrelation function R(t1, t2) depends on two variables t1,t2. If t2-t1=tau, then R(t1, t1+tau) It turns out that the power spectral density S(w), for a nonstationary autocorrelation function is equal to: S(w)= FT { }, the Fourier transform of the "long-ti...nonstationary autocorrelation but stationary PSD

order of autocorrelation/ASDF and interpolation?
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2004-01-16 15:40:00
I asked this before under another subject line, but perhaps it got lost. Assume I want the autocorrelation peak or best least squares fit of sampled data for non-integer sample offsets (e.g. the periods of the frequencies of interest are not a multiple of the sample interval). Should I inter...order of autocorrelation/ASDF and interpolation?

autocorrelation with 0 lag for LPC in speex library
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Anton - 2006-07-28 18:35:00
Hi, I saw in the sources for the speex library (http://www.speex.org/) that they add some value to the first autocorrelation result. The results are used to produce a IIR with a levinson durbin recursion. float d; int i; while (lag--) { for (i = lag, d = 0; i < n...autocorrelation with 0 lag for LPC in speex library

autocorrelation negative values
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Thomas Magma - 2006-08-09 17:45:00
Hi, If your data consists of ones and negative ones then you get negative values in your autocorrelation function, but if your data is ones and zeros you don't. In an autocorrelation plot you often see large negative values on either side of your correlation peak. Is this a good thing or ba...autocorrelation negative values

Autocorrelation versus Cross-correlation
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Tao - 2007-03-14 06:29:00
Hello, I am trying to determine the frequency of a signal. Samples of the signal are taken from 2 channels at a time. After some filtering, I perform the autocorrelation of each channel, and the cross-correlation of the 2 channels. The autocorrelations, as expected, yield almost identical res...Autocorrelation versus Cross-correlation

problem with fft on autocorrelation data
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acc - 2007-03-31 07:17:00
Hi all, Thanks for reading and please feel free to comment. I am having problems with matlab fft on autocorrelation data. When performing a fft on my normalised autocorrelation data i got a imagnary part that is not equal to zero around x=0 and also at the near end of the x-axis, but, in be...problem with fft on autocorrelation data

autocorrelation of linear or logrithimic sweep
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2006-01-24 22:11:00
Hi, All, I have been reading quite a number of articles on measuring room impulse response using frequency sweeps, but none of them quoted the analytical formula of the autocorrelation of linear or logrithimic sweep. I remember seeing it in a underwater acoustics book but could not find it an...autocorrelation of linear or logrithimic sweep

Pitch calculation (FFT or autocorrelation)
0

gjunge - 2006-06-05 07:02:00
Hi, I want to show a Pitch graph/curve of a wave file. I saw that good results can be made by using AutoCorrelation. I have the autocorrelation function and I also have the FFT function, but I don't know what I should put into the autocorrelation function in order to get a pitch line. I have a...Pitch calculation (FFT or autocorrelation)

sample autocorrelation matrix eigenvalues negative
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doublehelics - 2011-11-29 04:08:00
Hey all, i am computing sample autocorrelation for some continouous valued data (using this: https://ccrma.stanford.edu/~jos/sasp/Sample_Autocorrelation.html) but the generated correlation matrix has negative eigenvalues. Is there a way to fix the autocorrelation matrix to have non-negative eigenva...sample autocorrelation matrix eigenvalues negative

image correlation and autocorrelation
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fisico30 - 2009-02-17 09:55:00
Hello forum, this is a simple one: I found two forms of autocorrelation for 1D signals: biased and unbiased. Does anyone know the difference? Also, all the signals or images we work with are finite in length. If autocorrelation is carried out, we need to shift the image around with respe...image correlation and autocorrelation

Good reference for pitch tracking by autocorrelation
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2005-10-06 05:13:00
Hi. Does anyone have a good reference for pitch tracking by autocorrelation? I do note that there is a very long thread on this topic, but it's too long to follow. So far I've written a very straightforward program to calculate autocorrelation in a signal and also a crude envelope follower to ap...Good reference for pitch tracking by autocorrelation

Autocorrelation matrix of a long sequence
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sasuke - 2009-04-16 01:39:00
Hi I am using MATLAB to generate close to 10^8 samples of a Rayleigh fading channel using Jakes method. Once I generate these samples, I have to then create a 20 x 20 autocorrelation matrix. I am using MATLAB to do this. MATLAB works perfectly for 10^6 samples, but once the number of samples incr...Autocorrelation matrix of a long sequence

When does sampled autocorrelation = autocorrelation of sampled sequence?
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Oli Charlesworth - 2009-02-28 20:21:00
Hello, It feels like this will be a standard DSP result that I should be able to dig up, but I'm not sure where to look, so here goes! If we have a continuous-time function, h(t) (assuming real and "sufficiently well-behaved" for now), then define the autocorrelation as: r(t) = int { h(...When does sampled autocorrelation = autocorrelation of sampled sequence?

Autocorrelation matrix with matlab
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thom - 2006-06-29 05:46:00
Hi I would like to compute the autocorrelation matrix from a vector with Matlab. I don't have the statistical signal processing toolbox (I can only use "cov" and "corrcoef" functions, or build my own function). Could someone explain how I can do? Thanks a lot. Thom ...Autocorrelation matrix with matlab

Autocorrelation
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angelredrose - 2008-11-17 11:01:00
Hi, I am trying to understand the autocorrelation function for better timing resolution. I am bit confused how to find out the auto correlation PEAK from the output of M-Sequence? and What is the impact of distance between the two peaks? In other words, the impact of the length of the M-Sequence? ...Autocorrelation

autocorrelogram have bias?
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rune2earth - 2008-03-24 09:53:00
Hello I'm working on analyzing neuroscience data using the autocorrelation function. I discovered that it has a negative bias (for all lags except zero lag), that exactly matches up so that the sum of all is zero. This is in disagreement with what most textbooks write, for example this taken fro...autocorrelogram have bias?

Power Spectrum from Autocorrelation vs. FFT
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Navraj - 2007-07-24 16:34:00
I have two questions: 1) Is there a difference b/w the terms 'power spectrum' and 'power spectral density'? They both seem to indicate power vs. frequency. 2) Suppose you are given a random sampled data sequence x[n], and you have to find its power spectrum. - Can we find the spectrum by ...Power Spectrum from Autocorrelation vs. FFT

Re: Newbie, heart data analysis - detecting peaks?
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v - 2004-01-13 09:29:00
Hay Datura, this problem is very similar to the CELP coding algorithm stage named "Tone detection and tone period estimation". This procedure is rather robust and is proven in every CELP coder. The idea is to calculate the autocorrelation function for delays which belong to the human pulse pe...Re: Newbie, heart data analysis - detecting peaks?

Is autocorrelation of real sequences an homomorphic system?
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2006-07-10 17:22:00
I am working over estimation of fundamental frequency and spectral shift estimation, using autocorrelations and cepstral analysis. The Cepstral analysis is an homomorphic system, is possible to calculate as: X(w) = FFT[ x(n) ] c(n) = IFFT[ log |X(w)| ] The autocorrelation function is possi...Is autocorrelation of real sequences an homomorphic system?

Proof regarding autocorrelation of a pulse in white noise
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Craig - 2003-06-30 17:31:00
Let x[n] = s[n] + p[n] where s[n] is complex Gaussian white noise (GWN) and p[n] is a complex signal in the for Ae^{j2pi w + phi} where w is radian frequency and phi is a phase factor. I want to show that if I do the autocorrelation of x[n] (ie x[n]x[n-1]* , where * denotes the complex conj...Proof regarding autocorrelation of a pulse in white noise

Re: regarding white noise
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2005-12-22 15:06:00
> I want to know why white noise floor is added to the autocorrelation > function in the lpc analysis. I'm not an expert with LPC, but I know with adaptive dsp, you need to keep the inverse of the autocorrelation matrix stable. This is especially true with highly self-correlated signals. ...Re: regarding white noise

Re: Filter Method for Simulation of Wireless Channel
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2006-10-17 17:07:00
And another quickie... how is autocorrelation related to rate of change? A Rayleigh variable has an autocorrelation which is a Bessel function. Could I say that the channel is slowly fading if the symbol duration is "way less" than the main lobe of this Bessel function? ...Re: Filter Method for Simulation of Wireless Channel

In reality, how do people measure autocorrelation function?
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lucy - 2004-11-28 21:31:00
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 u...In reality, how do people measure autocorrelation function?

Re: Correlation Threshold Meaningful Value
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Rune Allnor - 2005-11-25 04:55:00
newsnetstudent wrote: > Hi, > > The autocorrelation of a signal X is generally bell-shaped with maximum > value at the middle. I am just wondering, from what a threshold value we > can assume practically that the signal autocorrelation is null? > > Assume that the maximum value of th...Re: Correlation Threshold Meaningful Value

Phase detection using Autocorrelation
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Kenny_EE_UTD - 2006-10-13 07:23:00
As part of a senior design project designing a QAM modem. One major issue that I am trying to tackle is the ideal of tracking the phase of the incomming signal to the reciever so that the data can be sampled at the appropriate times. I am currently playing with the ideal of using the autocorr...Phase detection using Autocorrelation

Pitch Estimation using spectral Autocorrelation method.
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2014-03-12 06:11:00
please help me to find pitch of a speech signal using spectral autocorrelation method. Thank You Regards Girish Babu S ...Pitch Estimation using spectral Autocorrelation method.

spreading code with low autocorrelation
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Thomas Magma - 2007-08-20 14:25:00
Hello, I'm looking for a spreading code that I can output from a microcontroller (PIC). The sequence must have low autocorrelation with a good merit factor. It should be a long sequence of between 4000 and 20000 and does not have to be done with a LFSR (shift register) since I have lots of ...spreading code with low autocorrelation

Re: Convolution and Correlation
-6

Randy Yates - 2003-12-25 12:01:00
Vimal wrote: > Hello all, > > When the two sequances are symmetrical then the correlation and the > convolution are same from the classical definitions. Actually this is true if only one sequence is (even) symmetric. > My query is that, the correlation (if not ergodic) has joint pdf ...Re: Convolution and Correlation
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