Questions tagged [cross-correlation]
The cross-correlation tag has no usage guidance.
346
questions
6
votes
3answers
525 views
Efficient calculation of correlation function every $N^{\rm th}$ point
I would like to calculate a long correlation function of length say, 1e6 points.
I have a prior knowledge that the correlation peak will be in point k*1000.
Is there an efficient way to apply this ...
1
vote
1answer
39 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 ...
2
votes
1answer
41 views
Why is peak of the signal taken as the Time Delay
I was reading this research paper titled 'The generalized Correlation Method for Estimation of Time Delay' by C. Knapp and G.C. Carter. They develop an ML estimator and in the introduction mention ...
3
votes
2answers
635 views
Signals cross-correlation
I am trying to measure phase difference between two received waves which are recorded by two separate PC's (microphones). The two PC's starts recording at the same time, then I make a sine wave sound ...
0
votes
1answer
55 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
votes
1answer
23 views
Relation between bandwidth and amplitude of auto correlation of chirp signal
I am trying to understand the properties of chirp signals and their characteristics.
I plotted the autocorrelation of a chirp signal in MATLAB.
How can I compute the relation between the amplitude of ...
0
votes
1answer
80 views
Estimate the time delay of two signals
I am having 2 sets of data data1 and data2 .I wanted to find the delay between the two datasets.
Assume data1=[1 2 3 4 5 6 7 8 9 10] and data2=[0 0 0 0 1 2 3 4 5 6].From the data I know that, data2 is ...
0
votes
1answer
36 views
Extraction of the phase lag form cross-correlation function
I would like to find out the phase offset that my signal contains at the receiver side. For this, I use the cross-correlation function, where I cross-correlate signal before and after matched filter. ...
0
votes
2answers
46 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
vote
1answer
59 views
Comparing spectrogram similarity over time
I have a data set of spectrograms from moving audio recorders. As the recorders get closer, I expect the spectrograms to become more "similar". I expect this "similarity" to be a ...
5
votes
2answers
42k views
Python - Normalized cross-correlation to measure similarites in 2 images
I'm trying to measure per-pixel similarities in two images (same array shape and type) using Python.
In many scientific papers (like this one), normalized cross-correlation is used. Here's an image ...
1
vote
1answer
53 views
RF-Chain Signal Delay for Sensor Switching
Lets have a RF-chain as above with system bandwith from HP corner to the green line say 1 MHz.
The signal accumulates delay as it passes through this analog chain, and due to it being non-liner filter ...
2
votes
1answer
46 views
Method to generate binary sequences with desired cross-correlation and autocorrelation properties
I am looking for a method to generate two binary sequences of length $N$ with the following properties:
Very good cross-correlation for all shifts.
Good enough autocorrelation for all shifts except ...
1
vote
1answer
26 views
How does a correlation receiver ensure which transmitted data does a user see?
Hello! I understand that using correlation, one can set up a system wherein multiple users can transmit at the same time using the same channel. And theoretically, I understand that if the correlation ...
1
vote
1answer
81 views
Real Data Complex Transfer Function using H0, H1, H2 Estimators
BACKGROUND:
This question is attempting to consolidate material discussed in two previous topics. These are:
Understanding the H1 and H2 estimators @Pontus S
Frequency-domain deconvolution: "...
1
vote
1answer
61 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 ...
0
votes
2answers
90 views
audio signal time delay estimation(TDE) in indiviual and separate mics
common TDE problems algorithms(such as GCC) often require audio signals in different mics concurrently, however, is it possible to estimate audio signal time of arrivals(ToA) in different mics ...
0
votes
1answer
518 views
Confusion with data after cross correlation
Surely this question has been answered before in parts but I cannot find one solid answer. Ultimately I am trying to calculate the audio delay between two signals I am recording on USB microphones. ...
0
votes
1answer
76 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 ...
2
votes
1answer
850 views
Autocorrelation of Addition of Two Independent Signals
Given a random signal $ Z \left( t \right) $ which is addition of two independent signals $ X \left( t \right) $ and $ Y \left( t \right) $ with constant parameters $ a $ and $ b $:
$$ Z (t) = aX(t) + ...
5
votes
1answer
541 views
Finding dependence between two sparse signals
I am new to signal processing and would really appreciate your help. happy to provide more context/details.
In my research, I have a system that has many sensors $X_1, \ldots, X_N$ and using this ...
3
votes
2answers
680 views
DOA estimation 2 sources time delay estimation uniform array
I am new to signal processing, so sorry if the question is superbanal. I have been spending more days than I would admit on this and can't find the error.
I have two triangle waves that are emitted ...
1
vote
1answer
656 views
Cramer Rao Lower Bound for Cross Correlation (Time Shift Estimation)
UPDATE 2
Okay, I think I understand now why the defined CRLB is not applying to my use case.
In my use case, we have very high SNR, and the the first signal $x_1$ is always the same. So the classical ...
0
votes
1answer
1k views
Cross Correlation in Java (Android) Using FFT (Frequency Domain Convolution / Correlation)
I want to implement cross-correlation with the start-symbol and the signal using FFT.
I zero-pad both signals to length N = x.len + y.len -1
Using the convolution theorem:
...
3
votes
2answers
3k views
Correlation Using FFT / IFFT (Convolution in Frequency Domain) in Java
I try to find about the delay between two audio files using Cross Correlation in Java. I've already done this algorithm so far that i get a idea about how many samples is the delay.
FFT x1 -> Zero ...
5
votes
2answers
1k views
How to calculate the phase shift AND time delay of non-periodic signals
Say I have two non-periodic signals, $f_1(t)$ and $f_2(t)$, with Fourier transforms $F_1(\omega)$ and $F_2(\omega)$. Basically, I need to line up $f_1(t)$ and $f_2(t)$ as close as possible, and I am ...
1
vote
1answer
204 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 ...
2
votes
1answer
505 views
Finding baseline (reference) of nosiy data and lag/lead between 2 signals
I have 2 datasets which vary with time as shown in the figure - Sa – Red , Sb – BLACK . I am doing the analysis in R. The entire dataset and a segment of data from 30 - 31 s are shown below -
-
As ...
4
votes
1answer
728 views
What Does It Mean When Cross Correlation Between Two Images Occur at Negative Coordinates
I am using Matlab normxcorr2 to calculate the cross correlation between several images, something like what has been done here: in MATLAB documentation. There are some of the examples that I get ...
0
votes
1answer
28 views
Difference between cross correlation definitions (signal processing / random processes)
I'm trying to understand the similarities/differences between the following definitions for cross correlation)
Signal Processing: (or it's discrete equivalent)
$$R_{XY}(\tau) = \int_{-\infty}^{+\infty}...
0
votes
2answers
97 views
Which algorithm could be used to compare two waveforms from an oscilloscope in XY mode?
I would like to receive some hint as to which algorithm could be used to compare two waveforms from an oscilloscope in XY mode, as shown in the image:
Note that the image shows a percentage ...
2
votes
0answers
33 views
Blind TDOA Estimation
I am not EE or DSP engineer, however I am working on a project that uses TDOA estimation for location finding. I am able to get the localization algorithm working using cross correlation to estimate ...
0
votes
1answer
45 views
What is the difference between Goertzel algorithm and cross correlation in time
Im reading https://en.wikipedia.org/wiki/Goertzel_algorithm,
when we want to discover the amplitude of a some frequency in a given signal what is the difference between applying Goertzel algorithm and ...
0
votes
2answers
124 views
Two different definitions of cross-correlation
I have come across two different definitions of the cross-correlation function:
$$
R_{XY}(\tau) = \int_{-\infty}^{+\infty} x(t) y(t+ \tau) dt
$$
and
$$
R_{XY}(\tau) = \int_{-\infty}^{+\infty} x(t)...
0
votes
0answers
35 views
Cross-correlation estimation in MATLAB using a method similar to pwelch for the PSD
Is there a function in MATLAB to estimate the cross correlation function of two wide-sense stationary signals (or the autocorrelation of the signal with itself) in a way similar to the estimation of ...
0
votes
0answers
28 views
Generating data with given Auto and Cross Correlations
I have two discrete vectors $\mathbf{x}_1$ and $\mathbf{x}_2$, and I'm trying to generate more data $\mathbf{f}_1$ and $\mathbf{f}_2$ that has some basics properties of $\mathbf{x}_1$ and $\mathbf{x}...
0
votes
1answer
510 views
Time delay estimation between two complex signals(IQ)
I need to time align two complex signals. The two signals obtained were at different RF frequency before digitisation. So,I have two complex signals(IQ) and I need to do delay estimation and apply ...
0
votes
0answers
29 views
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 ...
2
votes
1answer
137 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-...
0
votes
1answer
92 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 ...
1
vote
3answers
1k views
Downsampling from 100Hz to 60 Hz
I have two sensors measuring a single time varying signal . The first sensor (reference sensor) is sampling the data at 60 Hz and the second sensor (test sensor) is sampling the data at 60 Hz. I ...
0
votes
2answers
61 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 ...
0
votes
0answers
35 views
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,...
1
vote
1answer
50 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 ...
2
votes
1answer
715 views
Normalized Cross Correlation Operation
According to my question about separability of Gabor filters in this link, I want now to convolve my image with this separable filter by using the normalized cross correlation operation. Assume my <...
4
votes
3answers
5k views
GCC-PHAT (Generalized cross correlation MATLAB)
I've been trying to implement generalized cross correlation with a PHAT weighting function for a while now, and cannot get it to work. I have tried correlating using MATLAB's xcorr.m file, and it ...
0
votes
1answer
91 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 ...
1
vote
1answer
246 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 ...
3
votes
1answer
3k views
When to use cross spectral density versus cross correlation?
All my life, I've used cross-correlation to analyze the strength of the relationship between an input signal and the output signal. I use this to determine which ...
1
vote
0answers
39 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 ...
