Questions tagged [cross-correlation]

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4
votes
3answers
755 views

Estimate changing time lag between signals

Suppose I have two timeseries $x_1(t)$ and $x_2(t)$, shown in the image that I drew below. They look almost identical in general form, except some features are shifted slightly in time from one series ...
1
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0answers
950 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....
0
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1answer
142 views

Applying a window to input signal

I am sorry if I say any thing silly .Please forgive me.I want to apply a window to input signals.I have two signals each of which contains zeros (462 samples) and non zeros data (38 samples).I want my ...
9
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1answer
6k views

Auto Correlation vs Cross Correlation vs Convolution and their applications

I know from wikipedia that auto correlation in done on the same signal while cross correlation is done on different signals.But what does this actually imply in terms of application.I can always apply ...
1
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1answer
273 views

find cross correlation lag by optimization

I have data from many closely located sensors (geophones). These are often contaminated with coherent noise which I need to remove. Some of the most effective de-noising methodologies work if the ...
0
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1answer
859 views

PSS convertion from Frequency to time domain

Hi I have a question regarding primary sync signal in LTE. It is generated in frequency domain and its length is 63. How to convert this signals frim frequency to time domain. Should I use IFFT? what ...
1
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1answer
193 views

Mismatched offset when computing cross-correlation using FFT

In MATLAB if I compute the cross-correlation of 2 arbitrary signals using the xcorr function I get exactly the answer I expect. If I then calculate the cross-correlation using element-wise fft ...
0
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1answer
245 views

How to compare the syllable extracted from the audio

I need to recognize just one bird. I am trying to compare the syllables extracted from the sound samples. As a result of the spectrogram function, the power spectral density is taken from the sound. ...
1
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2answers
545 views

Audio template matching - power correlation?

I'm looking at some code that matches audio templates in a longer audio file. The calculation correlates the power spectra of the template and audio file, maximizing over the possible alignments. This ...
0
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1answer
322 views

Cross-Correlation to find the similartity of songs

I have been working on a problem where I am given two songs which are of the same category but there is a time difference between them. Eg. one song starts at x sec and other song starts at y sec. So ...
1
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1answer
367 views

Scaling Data before Fourier transform

I am doing an experiment, where I am trying to get the same results from correlating two matrices in the fourier domain and then scaling the data by some constant. Method_1: Do FFT, Correlate the ...
6
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1answer
1k views

Implementing a Matlab filter to cancel cross talk between two sensors

I have two sensors that have a cross talk between them. I would like to cancel the cross talk. For this I recorded two tracks, where sensor no.1 (called x1) has some input, and sensor no.2 (called x2) ...
2
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1answer
225 views

Is jointly wss (wide sense stationary) a transitive relation?

I've been try to either prove or find a counter-example to the idea of jointly-wss being transitive. In other words: does ($x$ and $y$ are jointly wss) $\wedge$ ($y$ and $z$ are jointly wss) imply ...
4
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1answer
6k views

Computing cross-correlation of two images using OpenCV

I have a program that uses OpenCV to compute either the convolution or cross-correlation of an image with a specified kernel. I compute cross-correlation by setting the conjB flag to true when calling ...
1
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1answer
1k views

Baseline correlation for template matching

In normal cross-correlation or convolution between a signal and a template(say a small portion of the signal) the template is moved along length of the signal without changing the amplitude offset of ...
4
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3answers
3k views

Cross correlation with short or non periodic signals?

I am a total newbe to signal processing and i have a problem which may be quite trivial to most of you guys. I want to align two short sensor signals (speaking of max. 1000 samples recorded with ...
12
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5answers
6k views

Is up-sampling prior to cross-correlation useless?

Consider a simple case where two signals from two different sensors are cross-correlated, and the time-delay-of-arrival computed from the absissa of the peak of their cross-correlation function. Now ...
1
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0answers
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 ...
0
votes
1answer
227 views

Auto/cross correlation of a cosine in the context of an adaptive beamformer

I am currently reading chapter 13 of 'Adaptive Signal Processing' by Widrow and Stearns, so if anyone happens to have a copy of the book to hand it could be helpful. I am reading the chapter on "...
4
votes
2answers
1k views

Subtracting Original Audio Signal

here is my scenario: one speaker is sending a chirp, and a microphone is recording it as well as all following echoes. The function of the chirp is already know. My goal: subtract the original chirp ...
0
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0answers
54 views

filter out an expected but not regular signal

I am stuck with a case where I need to get rid of a portion of sinusoidal signal that suddenly appears in my main signal (sine wave). my total signal will look like: $ s(n) = \begin{cases} A\sin(\...
0
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0answers
367 views

“Circular shift - invariant” distance

Couldn't decide whether the question belongs on Mathematics or here, but I guess I'll ask it here. I've got a discrete - valued function defined on a finite segment of a line that looks like this: ...
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2answers
1k views

Cross correlation peak value

I would like to measure the time delay between two signals. By applying the cross correlation I get the time delay or number of samples by the location of the cross correlation peak, however I am ...
0
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0answers
2k views

Why Normalized Cross Correlation Score of different templates is high?

I am using OpenCv's built in template matching function to search for an object in image. I am using Normalized Cross Correlation Method.The function is returning a value which I think indication of ...
0
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2answers
195 views

“Perfect waveform” for cross-correlations?

I am well versed in cross-correlations, as my masters thesis heavily relied on them for music classification and beat detection. So this question focuses more on the signals that I am running an ...
3
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1answer
3k views

Cross correlation vs FFT for finding phase between 2 signals

I have been struggling with this issue for months now, trying to understand which one to pick: FFT or cross correlation. I am given a sine wave (with phase, amplitude, frequency and time vector ...
3
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4answers
377 views

“cascaded” cross-correlation

so, first let's do this for the circular correlation case (it might be easier). let's say we have three real and periodic functions or signals $x(t)$, $y(t)$, $z(t)$ all with period $2 \pi$: $$ x(t+...
1
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2answers
3k views

Matching 2 audio files

I'm doing research on how we can do matching between 2 audio files using Android to see if they have the same content or not. After doing lots of research, I have concluded that I must do 2 main ...
0
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1answer
77 views

Avoid saturated pixels in cross-correlation computation

I am doing template maching using Normalized Cross-Correlation for measuring similarity between template and image. However, some images from my dataset contain saturated pixels (overshoot) which ...
1
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2answers
3k views

fast 2D cross correlation algorithm

I want to match a small template to a larger image, that the distance between the template and the subimage with the same size of the template is minimized. It can be solved directly or by applying 2D ...
0
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1answer
1k views

Solution to Cross-correlation problem of 2 audio signals

There are 2 audio signals, X & Y. X is of 15 second duration. The duration of Y is not given. Y is a part of signal X (ie a small part of audio X is extracted & made into audio Y) I have to ...
-1
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1answer
1k views

Correlation : Cross correlation why we need to multiply the samples

I understand what books states about cross-correlation of signals and their mathematical representation: For continuous functions f and g, the cross-correlation is defined as: $(f \star g)(\tau)\ \...
-1
votes
1answer
104 views

phase amplitude transform as a solution to reverberation

I am trying to use generalized cross correlation with phase transform (GCC_PHAT) on some audio processing indoor, with the existence of low noise. I ve read here that by canceling the magnitude factor,...
1
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0answers
892 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 ...
1
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1answer
48 views

How to decode speaker gender from spoken transcript

I have 20 audio recordings (raw format) of people reciting the same ~50 word transcript. I would like to use audio signal analysis to decode speaker gender from audio recording. Intuitively, it ...
0
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1answer
1k views

Cross-Correlation : Comparing two signals or finding the location of a target

I read across places that cross-correlation of two signal (a radar sending a signal and receiving it back) one can detect the location (distance) of a target from a point and that cross-correlation ...
2
votes
1answer
941 views

What Information does the phase of a cross power spectra give me?

I obtain the cross power spectra by the following steps: compute the FFT of signal A and B Multiply A with the conjugate of B store it in C (cross power spectra) Now looking at the Phase of this ...
1
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0answers
125 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 ...
0
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1answer
316 views

Speech discrimination from animal sound

i am looking for discrimination of speech from animal sound if you take a 150ms frame of speech and bird as shown below, what feature can i extract from them so that i can effectively state the ...
1
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0answers
358 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 ...
9
votes
2answers
7k views

Phase Correlation - Poor Performance on Noisy/Blurred Images?

I have successfully tested 1D phase correlation algorithm to determine vertical shift between two synthetic images. When I moved to real images, however, it is not able to detect translation at all (...
1
vote
1answer
184 views

Fast cross correlation with limited range

I am measuring the phase shift between two pseudorandom signals using correlation ifft(A.conjugate()*B) and picking out the maximum). That works very well, but takes a lot of time. I roughly know ...
20
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2answers
5k views

Examples of Independent and uncorrelated data in real-life, and ways to measure/detect them

We always hear about this vector of data VS this other vector of data being independent from each other, or uncorrelated, etc, and while it is easy to come across the math regarding those two concepts,...
1
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0answers
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 ...
0
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0answers
116 views

Describing a time delay at a maximum for maxima and minima but tends to 0 elsewhere

I have two force-time signals obtained from a couple of force plates, corresponding to input/output signals for some system. Plotting the two together one of the first things I noticed was a time ...
3
votes
1answer
490 views

Ultrasound Signal Processing Methods

I am sending 6.6Vpp square wave across a narrow-band, 40 kHz Transmitter to a narrow-band, 40 kHz Receiver. I want to find a very accurate distance between the two (sub millimeter). My assumption so ...
2
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2answers
961 views

Time delay estimate and sampling frequency

This is an extention to my other question. My sampling frequency is only about 2x my tone frequency. I want to estimate time delay of arrival using this signal. I am generating the tone signal so I ...
1
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1answer
682 views

Upsampling signal for cross correlation

I am recording a 17khz signal at a sample freq of 44.1khz. I want to perform cross-correlation between the received and transmitted signals for calculating TDOA. But when I do xcorr, the results are ...
1
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1answer
704 views

Time delay estimation using ultrasound

I have a sound source that generates an ultrasonic pulse. I have two microphones seperated by a distance which are at a distance from the source. I want to find the time delay of arrival of the ...
0
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2answers
1k views

Matching two audio inputs (signals) [duplicate]

this is for an application in which passwords are stored in the form of audio inputs . In order to provide user access , the password(in audio form) will be matched with already stored password(audio ...