Questions tagged [cross-correlation]

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cross correlation of minus one

I know that a cross correlation value of +1 between two signals means maximum similarity, and a cross correlation value of zero means that the two signals are completely dissimilar. What does a cross ...
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Can cross correlation be used to see if filtering of a signal has changed it too much?

I am filtering a signal, and want to check if I am not over filtering it. I am doing a low pass filter, for a signal of input frequency of 512Hz, first with 250Hz pass band, then )I was intending to ...
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37 views

Impulse response $h[n]$ from input and output signal using cross correlation on Matlab

I have two signals on Matlab, one being input and the other output. I want to know if taking the cross correlation of these signals would give me the impulse response?And if so, will taking the ...
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How to prevent (or remove) aliasing when a cross-correlation between spectra is performed

This is my problem: I'm implementing a tool which cross-correlates a spectrum (fluxes as function of wavelength, obtained directly from an instrument) with a template (fluxes as function of wavelength,...
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2answers
55 views

$f \star (g \,* \,h) = (f \star g) * h$?

In this paper that I'm reading, I see this equation: $$S_0 \star (S_0 * N) = N,$$ where $\star$ denotes cross-correlation, $*$ denotes convolution and $S_0 \star S_0 = \delta$. Is it true in general ...
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1answer
45 views

Is there any way to align temporally two signals in spectrogram?

I am keen to know that If I have two signals say : Farend_signal (y[n]) and Nearend_signal (x[n]) and x[n] also contains an echo of y[n] with some delay. Is there any technique to align these two ...
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1answer
20 views

How to run Welch’s method on cross-spectral density

I have a multivariate time series and I’m trying to figure out the cross spectral density of all pairs of variables efficiently. I’m unsure of how to implement Welch’s method in this context. Do I ...
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1answer
84 views

Is `xcov()`More Accurate Than `xcorr()` to Compute the Cross Correlation of Signals with Non Zero Mean Values?

I have to compute the cross-correlation between two transient signals, which could be decomposed into a trend (with non-zero mean value) + noise. In particular I am interested in the max of the cross-...
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1answer
62 views

Cross-correlation of two signals

I want to find the direction of a sound source in 2D space. I use two microphones and one sound source for that. I have recorded audio data into two arrays. When a sound is detected, it starts to ...
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1answer
30 views

Map time/scene differences between two similar videos

Goal: Given two videos that are episodes from series but in different format (one Bluray/one TV for example), map the time differences between the two (which scenes are not in one of the two) and be ...
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25 views

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 ...
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1answer
73 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 ...
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1answer
31 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 ...
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1answer
73 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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54 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: <...
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1answer
98 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 ...
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1answer
105 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 ...
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1answer
57 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 ...
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1answer
59 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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25 views

The normalized cross-correlation of two signals

I wanted to calculate the normalized cross-correlation function of two signals. I use the command ...
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40 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 ...
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1answer
79 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 ...
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117 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
40 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
49 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 ...
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1answer
35 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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27 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
35 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(...
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1answer
98 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?
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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
35 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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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. ...
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1answer
79 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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31 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
66 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
36 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
60 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
168 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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23 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
33 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
44 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
90 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
58 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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74 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
69 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
63 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 ...
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326 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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106 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
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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