Questions tagged [cross-correlation]

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1answer
4k views

How to normalize output of $\tt scipy.signal.correlate$

I have 2 different signals and I'm trying to cross-correlate then using Python 2.7 and scipy.signal.correlate. How do I normalize my results (such that the max ...
4
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1answer
3k views

Correlation of two signals at different sample rate

I have a signal $X$ and I want to find signal $Y$ in $X$, I can achieve this by cross-correlation. Signal $X$ is sampled at $8000\textrm{ Hz}$, and $Y$ signal is sampled at $44100\textrm{ Hz}$. My ...
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1answer
207 views

Relationship between time average and cross spectrum

I have two signals $x(t)$ and $y(t)$ which I can sample at arbitrary $\Delta t$ and $N$. I am interested to the signals product time average $\langle x(t)y(t)\rangle_t$. In particular I want to ...
2
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1answer
329 views

Help in interpreting the auto correlation graph

I want to check if a time series is (a) random (b) independent. For these I am using the autocorrelation (AC). Autocorrelation refers to the correlation of a time series with its own past and future ...
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1answer
3k views

How to find the period of a noisy signal using MATLAB's $\tt xcorr$?

Here is my code: function [ T ] = FindPeriodicity2(x,Fs) ac=xcorr(x,x); [~,locs]=findpeaks(ac); T=mean(diff(locs)/Fs); end and when I pass the signal ...
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1answer
70 views

How to calculate the variation of delay?

I have 1 transmitted signal transmits to the receiver. Every time transmit, I collect data from the receiver, I use the transmitted which I just transmitted and received data, correlate them, then I ...
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2answers
1k views

How to calculate Time Delay Estimation?

I have 2 data files, which links are attached below: Transmitted data Received data Those binary data are read by this MATLAB code: %% EDIT: clear all; close all; format long; ...
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0answers
402 views
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1answer
782 views

identification of sounds within audio signals

I am looking for methods to identify sounds within audio files. I was hoping to find some ready-made user-friendly software to do this but haven't found it yet. I am familiar with Matlab and some C++...
2
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2answers
394 views

Features of a non-periodic signal for comparison

I am looking for comparing a signal (256 / 512 point discrete | non-periodic ) (obtained after extracting some features from the captured image) with a database of around 5000 signals (256 /512 point ...
4
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1answer
739 views

Time delay estimation in low SNR

So I am interested in finding delay between two noisy narrowband signals,for example, two arterial pulse waveform. I can easily get a correct estimate of delay using cross-correlation method, but it ...
1
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1answer
403 views

Understanding time delay estimation for GPS?

I really need help to understand these questions which is highlight, for the GPS situation, I hope anyone who has been working in this situation before, please help me to have a clear understanding ...
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1answer
2k 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
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2answers
559 views

Range and motion in received signals by radar

I've got two signals which are consecutive received signals by a radar system. The signals' values are complex (in form $x+\textrm iy$). I have generated a trasmitted signal using the info available. ...
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0answers
429 views

Finding lag times for multiple time series

I have $N$ time series which have unknown time offsets relative to each other. I want to estimate the $(N - 1)$ time offsets, $\tau_{i,i+1}$, which maximise the sum of the cross-correlations between ...
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2answers
12k views

How to compute the cross correlation of two fuctions

I am trying to implement Matlab's cross correlation function but I can't seem to replicate the results obtained when using Matlab's built in function "xcorr". Documentation for xcorr can be found ...
2
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1answer
725 views

A special case of 2 jointly Weak-Sense Stationary (WSS) stochastic processes

I know that 3 conditions must be met in order a pair of stochastic processes $X(t)$ and $Y(t)$ to be characterized as jointly WSS: 1. $X(t)\;\; WSS$ 2. $Y(t)\;\; WSS$ 3. $R_{xy}(t_1,t_2) = R_{xy}(...
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1answer
2k views

xcorr in MATLAB for periodic function

I have a periodic signal and I want to find it's autocorrelation function. I can calculate it exactly: $$R_{uu}(h) = \frac 1M \sum_{k=0}^{M-1} u(k)\cdot u(k-h)$$ But will ...
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1answer
1k views

Angle of arrival (AOA) estimation using FMCW radar using MUSIC algorithm

I am working with FMCW phased array radar with only upchirps. The range doppler matrix is obtained using the two dimensional fast Fourier transform on multiple chirps. I want to obtain the angular ...
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0answers
743 views

Detecting delay and sample drift in audio files (wav, mp3, etc.)

In my application, I have an audio recording with background music. I know which song is playing in the background and have a copy of the original song (wav, mp3, etc.). The goal is to align the ...
3
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1answer
453 views

remove zero padding effect crosscorrealation

I am trying to make the cross correlation on the frequency domain and I use the fft function which takes power of 2 input data so I must pad with zero my incoming sample signal and localy generated ...
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1answer
790 views

Time-domain cross-correlation with padded signals [closed]

I have a frequency domain cross-correlation implementation written in C (based on: https://github.com/dMaggot/libxcorr). It uses the library FFTW3 and this is the gist of it: ...
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0answers
184 views

Cross Correlation shows peak at the same location every time

I have a signal which is taken from an accelerometer and I'm trying to match patterns between different windows of the signal by cross correlation. To do this I take different windows of the signal, ...
1
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1answer
5k views

Cross correlate a 2D array

I have a 2D array of eeg data with shape (64,512) - 64 electrodes, 512 timepoints I want to calculate the maximum cross correlation (irrespective of lag/time shift) between every single electrode, so ...
0
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1answer
185 views

How to use MATLAB's $\tt xcorr$ to find index of a section inside a whole recording?

Trying to find the index offset of a short section of an audio I have taken out of my recording with cross-correlation, but this method sometimes succeeds finding the index of the short section ...
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1answer
316 views

Can anyone help with cross correlation error in Simulink?

I am sorry if I say any thing silly. I have a vector x below and trying to implement correlation with itself (lets say x2) in Simulink, but getting error. I am ...
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4answers
43k views

What is the difference between convolution and cross-correlation?

I've found on multiple sites that convolution and cross-correlation are similar (including the tag wiki for convolution), but I didn't find anywhere how they differ. What is the difference between ...
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3answers
207 views

How can define an indicator which measures the degree of similarity between two signals?

The similarity of two signals is calculated by cross correlation. But, how to define an indicator which quantitatively measures the degree of similarity between two signals? Thanks.
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2answers
502 views

matched filtering in GSM

After the estimation of channel impulse response (using the training sequence in burst), to cancel the effect of channel on the received signal, I think, we should convolve the received signal with ...
4
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1answer
2k views

Cross-correlation or cross-covariance of non-zero mean signals

Cross-correlation for uniformly sampled signals is defined as [1] $$(f \star g)[n]\ \stackrel{\mathrm{def}}{=} \sum_{m=-\infty}^{\infty} f^*[m]\ g[m+n].$$ Cross-covariance for wide-sense stationary (...
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1answer
768 views

Is Cross correlation between stationary random signal and noise zero for all lags?

If $x(n)$ is a stationary random process (let say small 20ms window of speech which can be assumed stationary) and $v(n)$ is said to be uncorrelated noise, can we say that cross correlation of $x(n)$ ...
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1answer
1k views

What is the difference between normalized peak of correlation, versus peak of correlation divided by its average?

Given a template, and a signal, the question arises as to how similar the signal is to the template. Traditionally a simple correlation approach is used, whereby the template and a signal are cross-...
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0answers
362 views

Audio - TDOA and $\tt xcorr$, find the 'best' peak

I try to locate a mobile device using multilateration. The mobile device acts as the receiver and in the room I have three speakers. To calculate the position I need the time difference of arrival (...
3
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1answer
531 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 ...
1
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1answer
99 views

How to find the time instant where my sent signal and received signal can synchronize?

I am having two .wav files, one is modulated wave that is made into a .wav file and another is a recieved .wav file which is recorded from microphone while playing first modulated .wav file. So now ...
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2answers
54 views

How to discover an image clone

I have an image depicting a results of gel electrophoresis (it does not really matter - it just means: no bodies, faces, predictible objects) and I have a strong suspicion that a part of the image ...
1
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2answers
2k views

How to find a maximal possible value of a cross correlation

Is there any way of calculating a maximal possible value of a cross correlation of two signals whose maximal amplitude and sample rate is known? To make things clearer, , signals in question are ...
9
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1answer
2k views

Synchronizing Two Audio Tracks

I would like to implement an algorithm that synchronizes two audio tracks. The two tracks are very similar; you can imagine they are two recordings of sound (not necessarily music) from two ...
4
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1answer
551 views

How is cross-correlation related with orthogonality?

In linear prediction we can say that in case of optimum linear predictor the error with be orthogonal to data. And when we derive minimum mean square error for $\underline{y} = \mathbf{a}\underline{x} ...
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2answers
855 views

Convolution theorem for cross-correlation

Forgive me is this is an ill-posed question. Is there any such thing as a 'convolution theorem' for the cross-correlation. Namely, the convolution theorem states that: $$ x[n] * h[n] = \sum_{k=0}^{...
4
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1answer
89 views

Getting error in fit

I was wondering if anyone had run into the problem of trying to estimate errors in their signal processing on spectroscopic data. I know that many people use spectroscopic techniques to estimate ...
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1answer
1k views

Real-time delay between signals

I currently have a real-time noise suppression algorithm based on two inputs from different microphones. It has passed most tests that I have thrown at it, however when the signal I am trying to ...
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5answers
14k views

Time delay estimation of oscilloscope signals using cross correlation

I have recorded 2 signals from an oscope. They look like this: I want to measure the time delay between them in Matlab. Each signal has 2000 samples with a sampling frequency of 2001000.5. The ...
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0answers
265 views

Fast Normalized Cross-Correlation for Stream-Data

I read some papers about fast normalized cross-correlation techniques. Most of them are used to identify a template in an original image. I was not able to find information about input-data in a ...
0
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1answer
161 views

Is there any reason that cross correlation would perform well or poorly on sparse binary arrays?

I am using matlab xcorr to correlate simulated photon count data that has some Gaussian random noise set on top of it and it is working fine when the average value ...
1
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1answer
345 views

Code generation for `sum` function in MATLAB

In cross correlation we use the below command to calculate the sum after elementary multiplication of the vectors. But when we try to convert this Matlab code to vhdl using HDL coder, this command is ...
3
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2answers
687 views

Map time difference between two similar videos

Question: Is there any software, source-code, or well documented and easily implementable research (I am not afraid for a little bit of Python) to do the following: Take two similar videos from ...
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1answer
571 views

Bartlett's and Welch's Method for PSD

Lets say. I have an image of 100 samples, and I want to find the presence of smaller image of 24 sample using cross-correlation in the fourier domain. I use Bartlett's and Welch's method for PSD, ...
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0answers
453 views

Problem in hardware implementation of cross correlation without xcorr

Sorry for any thing silly! Matlab uses the built in function called 'xcorr' to find correlation of two signals.In VHDL xcorr is not defined then correlation can be written using for loop ...
2
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1answer
624 views

Calculating similarity between bit strings/signal

I have a project I'm working on where I'm trying to efficiently compare sequences of binary data to determine how similar they are. Basically, a sequence might look like this: 1001010010100011110... ...