Questions tagged [cross-correlation]
The cross-correlation tag has no usage guidance.
327
questions
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Is it possible to normalize an un-normalized cross-correlation vector after computation
I have a C++ code that computes cross-correlation for a given 2 vectors as input. It doesn't have an implicit normalization or normalized implementation of cross-correlation. But I would prefer a ...
0
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1answer
33 views
CWT at low scales: PyWavelets vs Scipy
Low scales are arguably the most challenging to implement due to limitations in discretized representations. Detailed comparison here; the principal difference is in how the two handle wavelets at ...
1
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1answer
30 views
Finding delay where squared error between signal and data is minimal
I have a set of points which correspond to part of a known signal. What I want to do is estimate the delay between the set of points and the known signal.
In this case, I don't think cross ...
1
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1answer
68 views
Produce musical signal from instantaneous frequency
I'm implementing the Yin Algorithm in Python so as to extract the pitch of my voice when whistling or humming. My goal is to produce the Gate (Envelop Control) and CV (Pitch Control) signals which can ...
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38 views
How to use cross-correlation to verify speech data and determine delay
I have been experimenting with cross-correlation function to verify the presence of speech in a recorded file wrt a source file. I tried the following in Matlab:
<...
1
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1answer
83 views
Fourier Transforms, Convolution, Cross-correlation: what is their physical unit exactly?
Let us assume we are talking about real, deterministic, electrical signals $x(t)$ and $y(t)$ (magnitude in Volts).
There are different kind of Fourier Transforms. I made a table to summarize:
NB: By ...
0
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1answer
61 views
Proving the upper bound of cross correlation
I am reading about cross-correlation from this document and equation (5) states that
The maximum value of the crosscorrelation is not always when the shift
equals zero; however, we can prove the ...
1
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1answer
50 views
Convolution and Cross Correlation Blackbox
Suppose I was handed a blackbox that I know is either a Convolution filter or Cross-Correlation filter, and my job is to find out which it is.
My idea is to pretend that it's Cross-Correlation and ...
1
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1answer
39 views
GCC-PHAT always peaks at zero when estimating delay offset
My question is that when I used gcc-phat to estimate delay between two audio signals, it always returns zero offset. However normal cross correlation Xcorr gives a good result. I don't know the reason....
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23 views
The normalized cross-correlation of two signals
I wanted to calculate the normalized cross-correlation function of two signals.
I use the command ...
2
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0answers
36 views
Strange behavior in fixed-point FFT
This is a problem I encountered some time ago while doing my thesis, which still now, I am not sure to understand.
By then, I was implementing the circular correlation in an FPGA using this Xilinx FFT ...
1
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1answer
72 views
SVD vs matched filter
Reading about singular value decomposition (SVD) in the context of signal processing applications, one can separate the signal from the noise into orthogonal subspaces. On the surface this sounds like ...
2
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0answers
64 views
Fast calculation of normalization factor for normalized cross correlation
There has been a number of posts here I've browsed through that explain implementations of normalized cross-correlation in Python. One such implementation that is frequently cited is found below.
<...
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1answer
38 views
Interpreting the cross correlation results
I am new to this forum. I am just trying to understand how to calculate delay (in terms of samples) between two signals using cross-correlation function. I wrote a small Matlab code in order to ...
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2answers
44 views
Comparing similarity of two simultaneously recorded EEGs in freq domain
I have two EEG signals that are simultaneously recorded during the night (sleep). Imagine one device recorded from channel F4 and the other from Fp2. Now I would like to check the similarity of these ...
0
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1answer
34 views
Matlab: xcorr: Having trouble when I try to calculate delay between two sinusoids
I have a problem when I try to use Matlab built-in function for cross-correlation 'xcorr'.
Background: I created two sinusoids, one of them delayed in time. I choose center frequencies of these ...
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0answers
26 views
aperiodic auto correlation properties
I'm reading about PSC (primary synchronization code) in UMTS. It is a so-called Golay sequence.
It is said it has a good aperiodic auto correlation properties.
What does it mean (in terms of aperiodic)...
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1answer
30 views
Having Problem about DownConversion
I hope, you are doing well. I want to ask question about baseband conversion.
Background:
I generated two AM signals in MATLAB, which one of them is shifted in time.
I multiply the signals with $\cos(...
0
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1answer
31 views
Calculating the bit period
I want to calculate the bit period in my RF packets that I transmit them with 50Kbaud (Symbol rate=bit rate in my case) , how can I calculate the bit period?
0
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1answer
23 views
Spectral analysis of a cross correlation function [duplicate]
So it's widely known that the Cross Correlation of 2 signals helps us in figuring out the time delay in those signals by analyzing the peak of the correlation coefficient in the time domain.
For ...
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1answer
32 views
Cross-correlation with SDPSK modulation
I'm trying to detect a sync word in a signal using Symmetrical Differential PSK (bit 0 = +90° phase, bit 1 = -90° phase).
Given the signal is encoded in the phase difference between two symbols, the ...
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0answers
60 views
Probability of similarity for two random white noises
I'm looking for the method to calculate theoretical similarity of two random noises $x$ and $y$ with mean $0$ and standard deviation $1$, I've got also $12500$ samples of signal, sampled $2.5$ Ga/s.
...
0
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1answer
49 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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26 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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0answers
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
29 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 ...
1
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1answer
31 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
51 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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3answers
156 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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0answers
22 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
29 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 ...
0
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1answer
39 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 ...
0
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1answer
60 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 ...
0
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1answer
36 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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62 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 ...
0
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1answer
55 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
52 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
194 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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0answers
76 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:
$\...
1
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1answer
33 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
37 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
107 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
49 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
80 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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0answers
199 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
46 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
36 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
234 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 ...
