Questions tagged [cross-correlation]
The cross-correlation tag has no usage guidance.
313
questions
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33 views
Get the lag of a signal with respect to the other with cross correlation
I have 2 vector of length 20 each. The first 15 entries of $a$ are exactly the same as the last 15 entries of $b$. There is random noise in the 5 last entries of $a$ as well as the 5 first entries of $...
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19 views
Instantaneous frequency, PLLs, frequency mixing, cross-correlation and the cross-correlation matrix
This is as much a request for comment and critique as anything else. I am looking at tracking how a system perturbs an input that is a (real) sinoid of varying frequency.
...
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7 views
Clipping cross correlation peak range in noisy signal
The result of a cross-correlating a signal of deltas (period N) with a signal of white noise that's containing a periodic signal (of period N, Length and Position) is plotted in the image.
I want to ...
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2answers
22 views
Cross Correlation of output with input is equivalent to impulse response of a large bandwidth input (LTI System)?
What is the practical way to found the impulse response of a system ? As impulse function has a very large amplitude at zero time (analog signal).
So the cross corelation of output of a large ...
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1answer
26 views
Correlation of discrete time periodic sequences
So I was reading this textbook - Digital Signal Processing by Proakis and Manolakis. The authors define the cross-correlation operation for 2 energy signals $x(n)$ and $y(n)$ in section 2.6.1 as:
$$ ...
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2answers
46 views
Why Convolve instead of Cross-Correlate for Detection of Known Signal?
I am reading a journal on optimal signal detection by mobile sensor. It is mentioned:
How should we plan to robots’ motion in order to maximize the detection probability? Assuming the source emits ...
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2answers
144 views
Cross correlation and cross power spectrum for signal + noise
Quick question about my understanding of cross correlations and cross spectral densities.
Let $C_{ab}$ be the cross correlation between the signals $a$ and $b$, i.e., $C_{ab}(\tau) = \langle a(t)b(t+\...
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20 views
Increasing samples per symbol degrades correlation between signals
I am trying to implement a simple pseudo-noise (PN) ranging simulation.
I have used this GNU Radio example, and I have adapted it a bit to suit my needs.
Here is a screenshot of my flowchart:
The ...
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1answer
27 views
CDMA scheme that preserves constant envelope (NRZ/ASK shape)
(This is a followup question to Is this a "valid" CDMA modulation?)
Is it possible to find a CDMA scheme in which the receiver can only have a simple slicer?
In other words, for the ...
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1answer
30 views
Is this a “valid” CDMA modulation?
I am banging my head against (specific aspects of) CDMA for a few days. At the basic level I am confused about the interrelation between implementations that are modeled as mixing and fully digital ...
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1answer
33 views
Calculating PSD, Cross PSD by using FFT outputs
I am having the FFT results of two distinct voice signals. Let's say the FFT results of these two signals are of the form (a+ib) and (c+id). Now, I want to calculate the PSD of each signal and also ...
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1answer
30 views
Calculating Cross Power Spectral density between two complex signals
I have a small misunderstanding of cross power spectral density between two complex signals. I know that it is the Fourier transform of cross correlation between two signals. Let's say the complex ...
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54 views
pointwise cross-correlation, finding offset in same signals
Problem:
I want to find the correlation between two signals from point to point. That means that if they share y values then I want to know the x offset between them.
This is what I want in ...
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1answer
45 views
How to find correlation between two signals regarding peaks?
In a super-resolution task, I try to predict the higher frequencies of a signal.
X low-resolution (lr) is my input and Y high-resolution (hr) is the target. Where X contains only frequencies till 2 ...
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1answer
36 views
Why Cross-correlation work better than Generalized Cross-correlation GCC-PHAT in MATLAB?
Fs = 192000;
t = 0:1/Fs:(0.01-(1/Fs));
F1 = 10000;
x = 1*sin(2*pi*t*F1);
nSamplesGausswin = length(t);
w = (gausswin(nSamplesGausswin))';
s = w .* x;
this is ...
3
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2answers
95 views
Convolution v.s. Cross Correlation in Digital Image Processing
I understand that from mathematical point of view, only difference between Convolution and Cross Correlation is that Convolution is commutative, while Cross Correlation is not.
In many articles ...
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47 views
Why are the Fourier transforms of autocorrelation and cross-correlation different?
I'm almost definitely misunderstanding this, but as far as I can tell we can equate the Fourier transform of the auto-correlation function $R_{xx}(\tau)$ with power spectral density (PSD) like so:
$\...
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1answer
29 views
Variance of circular vector correlation
Say I have two zero-mean vectors, with a size of N and the translation between them is k. Say the image signal std is $\sigma_s$ and the noise std is given by $\sigma_n$. What is the variance of the ...
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19 views
What happens to crosscorrelation of two noise generator if one of them were to be inverted
I have two noise generator u1 and u2 and their crosscorrelation is given, what will happen to this crosscorrelation if u2 or u1 were to be inverted?
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0answers
51 views
How to extract information about each constituent 'wave' of a signal?
I have a vector containing wind speeds sampled at 1Hz over ten minutes.
I have applied a lowpass filter of 0.25Hz to get only the wind speeds I am interested in.
I now want to use MATLAB to ...
0
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1answer
35 views
Synchronize device to audio stream - Approach
I am working on a device which's actions should be synchronized to the audio played. The audio stream is known in beforehand and can be altered to contain signals for the synchronization. But the ...
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1answer
72 views
Difference Fourier Shift Theorem and Cross Correlation Theorem
can someone explain me the difference between the Fourier Shift Theorem and the Cross Correlation Theorem?
The shift theorem says that a delay in the time domain corresponds to a linear phase term ...
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2answers
44 views
Transforming digitized noisy signal before applying cross-correlation
I'm trying to grasp the concept of cross-correlation as it applies to CDMA in the GPS C/A signal where noise is involved and the SNR is low.
My understanding is that before calculating the cross-...
0
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1answer
61 views
Autocorrelation Computation with MATLAB
I have done the computation of the autocorrelation of a sequence (vector), here called "frame", and I have plotted it. Here the code:
The resulting graph is:
I do not understand the position of the ...
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118 views
Matlab normxcorr for 1D signals
I am very surprised not to find a version of normxcorr2 for 1D signals in Matlab ! I implemented something like that by hand (with 2 for loops, and normalizing the template as well as the window under ...
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0answers
41 views
Simulink cross correlation issue
here is the Simulink model that i'm using :
The matlab function script :
function tau = fcn(sig,refsig)
tau = gccphat(sig,refsig);
The errors :
2
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1answer
35 views
Synchronising audio in realtime without knowledge of original signal
Was doubting whether this is the right SE forum to ask my (elaborate) question, so don’t hesitate to let me know if it’s not. Also, if anyone knows of a better way to title the question, feel free to ...
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3answers
190 views
How to reliably compute the group delay of a comb filter
I applied the following FIR comb filter in real-time:
y[n]=x[n]-x[n-40]
Since this is an FIR, the group delay is D=(N-1)/2=20 samples. After applying the filter ...
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0answers
18 views
Cross-correlation, spreading out the error
I'm looking for a method to determine the most likely offset of a measured 1-dimensional signal to a reference signal. The reference signal does not need to be generalized and always has a similar ...
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0answers
19 views
Signal similarity analysis after cross correlation
I have a time series signal and using this as reference, from the main data set extracted possible matching sections using cross correlation technique.(xcorr matlab).Based on with the threshold xcorr ...
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0answers
10 views
How to Determine Phase Difference and Time delay between two wavepackets using cross correlation method through MATLAB?
I have 2 wavepackets with different Displacement Vs. Time values. I need to find the Time Delay and Optimum Phase difference(i.e the phase angle when the correlation coefficient with Time Delay is the ...
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1answer
71 views
Deriving the Langrangian interpolation polynomials in Cook-Toom convolutions
I'm working through Blahut's 'Fast Algorithms for Signal Processing'. Trying to develop an intuition for the Cook-Toom algorithm for convolutions as used by Lavin and Gray in their Winograd paper for ...
2
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1answer
70 views
GCC-PHAT for Multiple Sound Sources
Can GCC-PHAT be used to detect multiple time-delays (that is, having multiple acoustic sources simultaneously)? The documentation for the gccphat(sig,refsig) ...
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25 views
Pearson correlation coefficient vs mutual information
I recently computed both the pearson coefficient and the mutual information of two time series as well as the corresponding error bars, and what I find out in the end is a significant level of ...
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1answer
122 views
Cross correlation to compute delay between two lines does not work
I have zero experience with signal processing, and I am stuck in what I believe to be a very simple problem.
I am trying to use the xcorr in matlab to find delay between two signals.
The signals are ...
2
votes
1answer
85 views
Reduce noise of sensor by combining two
I've had the basics of signal in university but little real-life practice. I've got an acceleration sensor with a digital output signal (signed 16 bit value). This signal is a little noisy. The ...
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1answer
128 views
Discrete Time Fourier Transform (DTFT) cross correlation property
I came across this property of the Discrete Time Fourier Transform (DTFT) and I am having a tough time proving it.
In general, consider two real signals $x[n] \: \& \: y[n]$. If
$$ x[n] \...
3
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2answers
306 views
Is maximizing hamming distance the same as minimizing correlation?
For the design of an error correcting code, I might wish to maximize the distance between the codewords $\sum a_i \oplus b_i$.
For spreading sequences I'd like to minimize the cross-correlation at $t=...
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28 views
Decorrelation for Adaptive Feedback Cancellation: How does it work?
I am going through lecture slides on adaptive feedback cancellation right now, and several decorrelation measures are mentioned.
As I understand, these are important in order to avoid a bias in filter ...
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0answers
40 views
Measure How Much Pattern Is Present In Signal
I have some pattern signal. This pattern signal will be played in noisy room. Then it will be recorded and processed. I need to show that my processing algorithm improves the signal.
My idea is to ...
3
votes
1answer
192 views
Strong (0,0) pixel among an otherwise normal cross correlation peak
I am working on an imagery registration problem via cross-correlation and am seeing a weird phenomena sometimes. First, I am pre-processing each image by subtracting the mean image brightness from ...
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0answers
30 views
Phase lag changes cross spectrum
I have a same noise passing through two different ARMA filter. The autospectrum of first filter is given by S11=G1*G1*S_in where S_in is input spectrum created by set of random numbers.
Similarly the ...
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2answers
716 views
How to compare and measure the similarity between two between two signals?
I'm working on different sensors data, the question is this: I have two signals (coming from two different sensors measuring two different phisical charactheristcs of the same "object").
I know for a ...
1
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1answer
96 views
Why the spectral coherence is unity for all frequencies between single-frequency time series and itself
In the example below, I am plotting the coherence between time series and itself. The time series do has one frequency.The coherence magnitude was one for all frequencies. I wonder why it is not zero ...
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2answers
107 views
Cross-correlation of filtered random processes
I have a wide-sense-stationary (WSS) process $\{x(t)\}$ and two linear filters with impulse functions $h_1$ and $h_2$.
Let $\delta(\omega)$ be the power spectrum of $\{x(t)\}$ and $$H_1:\omega\...
0
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1answer
28 views
Detecting multi-path propagation when one acoustic signal is dominant
I am sending an acoustic signal from a source to a receiver where there are limited number of paths the signal can travel. I want to detect if there has been multipath propagation or not when one path ...
1
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1answer
176 views
Faster Algorithm to convolve/correlate two sparse 1-D signals in python (or any language)
I have two signals which I need to correlate or convolve. Each signal is sampled non-uniformly and the values of the signal I have with me are the timestamp and the magnitude of the signal at that ...
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0answers
22 views
Wrong estimate of lag by xcorr between a signal and its segmented identical copy in Matlab
In general I have a series of signals that each following is a bit stretched version of the previous. To find the incremental stretching, I crop the original signal into some number of short segments ...
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0answers
15 views
match a pattern in a stream of bits
I feel my question is somewhat related to this, but I'm not sure how to do what I want.
I get transmissions of ~1000 bits at a time, which may be corrupted by noise.
To try and infer data from ...
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0answers
8 views
Obtain points in signals which cause correlation
I've got two large .wav files (tens or hundreds of minutes each). I know that at some points these files contain very similar areas - actually, these areas are the ...
