# Questions tagged [cross-correlation]

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### 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 ...
422 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 ...
753 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 ...
69 views

### Minimum time delay that can be estimated between two sensors

Consider a 1-dimensional toy problem. I have two sensors at different points along the $x$-axis. Somewhere away from the sensors, a disturbance is created which travels towards the sensors, first ...
610 views

### Synchronizing signals with different sample rates

I am relatively new to signal processing, so I am still missing some basic knowledge, but I am trying to improve as much as I can. I am trying to synchronize two signals with matlab using cross-...
249 views

### Reliability of normalized cross-correlation with high lags

Say you have two signals with 100 data points in each signal. Then there are 20 time lags where the computation of the normalized cross-correlation between those signals only considers 10 or less ...
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 ...
772 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++...
638 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 ...
16 views

here is the Simulink model that i'm using : The matlab function script : function tau = fcn(sig,refsig) tau = gccphat(sig,refsig); The errors :
289 views

### Basics of Normalizing Cross-Correlation with a View to Comparing Signals

I'm trying to understand how cross-correlation is used determine the similarity of two signals. This tutorial offers a very clear explanation of the basics, but I still don't understand how to use ...
81 views

### Common mode signal cancellation on multi-channel system

I have a system consisting of 32 horizontal plus 32 vertical charge sensitive wires. They are part of a particle detector and each one is coupled to a charge amplifier consisting of preamp stage ...
132 views

### Iterative Auto and Cross Correleation Estimates

I'm looking for literature or other information that covers iteratively estimating the auto- and cross-correlation vectors and the auto-correlation matrix. Initially, I can assume the signal is wide-...
11 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 ...
27 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 ...
40 views

### Threshold for CAF Surface

I am calculating a time partitioned Cross Ambiguity Function (CAF) by adding the surfaces of different time-sectioned CAFs together. Meaning, I calculate a CAF using 10 seconds of IQ data, calculate a ...
55 views

### Time delay estimation of signals increasingly decorrelated

The problem may be summarized as follows: I have a stochastic signals and I want to measure an increasing delay, as depicted in the following picture. The picture represents the signal as it is being ...
102 views

### Subtracting audio signal emitted - trying to use spectral subtraction to localize moving objects

I am a Software Engineer without much signal processing background and currently spending and experimenting to get use to it. My scenario: Assume a speaker and a microphone array. A speaker emits an ...
465 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 ...
178 views

### Frequency Domain Variant of Pearson's Sample Correlation Coefficient?

Suppose that you need to find (i.e. acquire) $x_1$, a short data packet with a known bit sequence preamble (i.e. a PRBS BPSK), in $x_2$, quantized samples recorded from the output of an ADC. You don'...
438 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 ...
107 views

### Choice of axes in 1D cross-correlation of a signal in a 2D space

I am working on a research project in which we present an observer with a target moving in a random walk in a plane in front of them, and record the eye movements they make to track it. We cross-...
361 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 ...
425 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 ...
720 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 ...
180 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, ...
357 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 (...
264 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 ...
941 views

### Why correlation coefficient template matching perfoms better than cross-correlation and square-differences method

I am using this template in OpenCv's match template function by converting all images to grayscale. Here are my result using sum of square differences,cross correlation and correlation coefficient....
2k views

### Compare two voices and outline their similarity

I am trying to develop an application which records the voice of someone through a microphone. I will have a preset recorded voices for the same words. I then need to compare the real time recorded ...
877 views

### GCC-PHAT cross correlation

I am trying to implement GCC-PHAT in python. The approach is similar to the following two links: link1 and link2 It seems the only difference between GCC-PHAT and normal cross-correlation using FFT ...
124 views

### Time delay analysis in different binary sequences

I am extracting a property of a signal which I represent with either a 0 for absent or 1 for present. This property is extracted for each data point in a time series and in the end I am left with a ...
350 views

### Noisy Signal auto/cross-correlation

I am trying to understand the basics of the cross/auto-correlation if the noisy signal $y(t)$ which is received from the channel at the receiver. Here at receiver we want to estimate the noise in the ...
266 views

### ACF and PACF Confidence Levels for ARMA

I'm trying to figure out where exactly to draw the confidence levels for the autocorrleation function (ACF) and the partial autocorrelation function (PACF) for an ARMA model. For PACF I found that a ...
272 views

### Train Pulse Recognition in Medium Voltage Networks

I just started a project in the Smart Grids area. It involves the recognition and quick extinction of earth faults in a medium voltage system. The system works automatically and pretty much gets rid ...
196 views

### Finding audio signal time delay: cross-correlation vs. impulse response?

I need to find a time delay between the two audio signals, one comming from one set of speakers, and the other being the source signal that is initialy sent to speakers. I send some noise through ...
28 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 ...
17 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 ...
13 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 ...
6 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 ...
16 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) ...
16 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 ...
35 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 ...
55 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 ...
26 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 ...
19 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 ...
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 ...
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 ...