The tag has no wiki summary.

learn more… | top users | synonyms

1
vote
1answer
18 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 ...
1
vote
0answers
9 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
votes
2answers
86 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
votes
0answers
37 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 ...
2
votes
1answer
44 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 ...
0
votes
1answer
48 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
votes
2answers
61 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
vote
1answer
73 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
vote
1answer
79 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
votes
2answers
80 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 ...
2
votes
1answer
94 views

Cross-correlation of time compressed 1D signal

If I ave 2 otherwise identical 1D signals that are phase shifted from each other then cross-correlation is a perfect way to identify the time lag between the 2 signals. Now supposing I double the ...
2
votes
1answer
97 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 ...
0
votes
0answers
23 views

What is the time array in Generalized Cross Correlation method?

I work currently on a blind location of arrays of microphones and speakers. In my work, I have to find the time difference of arrival between a speaker and a microphone, with a high precision. So the ...
1
vote
1answer
29 views

A special case of 2 jointly 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. Rxy(t1,t2) = Rxy(t1 - t2) = Rxy(t2 - t1) ...
4
votes
1answer
192 views

Ambiguous results of phase correlation in pattern recognition

We are using phase correlation to find pattern on image and what we get is 15% of results is spurious. Ours pattern has 32x32 pixels and image for research has 32x512 pixels. So we put Pattern to ...
1
vote
1answer
67 views

Detecting a frequency pattern in the frequency domain

I am looking to detect a combination of frequencies in the frequency domain. For example, here is my spectrum: And I'm trying to detect the pilot tone. I have the FFT of the pilot tone: which ...
1
vote
2answers
111 views

Applications of Correlation in Signal Processing

There have been discussions on the differences between convolution and correlation, autocorrelation, cross-correlation, et al. In spite of looking at the visualizations, and understanding the ...
0
votes
1answer
56 views

how to calculate cross correlation of transient signal?

there. Let me have a noisy speech signal $y(k)$ as below. $$ y(k) = x(k) + v(k) $$ where, $k$ is the discrete-time index, $x(k)$ is clean speech signal, $v(k)$ is a zero-mean random process, ...
1
vote
1answer
108 views

Signal compare - cross corelation in frequency domain matlab

I need compare two signals. Signals have simliar shapes but completely different values (as on picture): So I think cross corelation in frequency domain should gave me a number that shows me how ...
0
votes
2answers
77 views

Normalized cross-correlation in detail

I'm trying to implement a normalized cross-correlation algorithm but I don't get what in fact is this measure. What confuses is the wikipedia definition: $\frac{1}{n} \sum \frac{(f(x,y)- ...
1
vote
0answers
36 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 ...
1
vote
1answer
402 views

How can I compute a time-frequency cross-spectrum in MATLAB?

MATLAB has a spectrogram function for the time-frequency analysis of a single signal. It also has a cpsd function for estimating the cross-frequency spectrum for two signals. However, cpsd averages ...
0
votes
1answer
139 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 ...
0
votes
0answers
182 views

Similarity of signals

I have a question concerning methods to find different aspects of "similarity" of signals. So, first, I'd like to characterize the signals to be dealt with: We have a number of close to rectangular ...
0
votes
0answers
37 views

Extract data that contributes to strong correlation

I need to discover the effect of hidden variables on on a predictor I'm working on. I have two random variables, which have around 50% correlation to each other, if all the data is counted for. The ...
2
votes
1answer
123 views

how could correlation-based image patches matching works?

In general, correlation-based image matching can be referred to as $$c(I_1,I_2) = \sum_{x \in patch} f(I_1(x), I_2(x))$$ , I do think normalized cross-correlation like $$ncc(I_1, I_2) = \sum_{x \in ...
1
vote
2answers
190 views

Given an experimental FFT plot, how to find the best match from a set of generated FFT plots?

What I'm trying to do is, given some experimental data and it's (magnitude normalized to 1) FFT, match the FFT with one of say 1000 other (magnitude normalized to 1) FFT plots. Please note that the ...
2
votes
1answer
162 views

How do you find signal similarity when one signal has zero values? Correlation alternative?

I'm using cross-correlation to look for a Barker code in a BPSK signal. It occurred to me that if I send out a zero DC valued signal proceeding the barker code, it won't affect the correlation ...
1
vote
0answers
47 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 ...
1
vote
3answers
203 views

Is possible to compare to audio samples with cross-correlation [duplicate]

Is it possible to compare two audio samples(meaning find word from one in another) realtime with cross-correlation?
0
votes
1answer
476 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 ...
2
votes
1answer
66 views

Embedded Correlation Function

I'm trying to write a correlation function on an embedded device. Because its embedded, I need to make sure that the memory/CPU usage is minimum. Here's the deal: - I have a saved waveform sampled ...
1
vote
2answers
374 views

Cross-correlation peak

How get cross-correlation peak and based on it calculate correlation score for similarity of two audio samples. SO far I've FFT two samples complex conjugate second multiply results IFFT ...
2
votes
2answers
174 views

Why is image blurring called convolution and not cross correlation?

I've always thought that image convolution is a weighted sum of the nearby pixels using the convolution kernel as weights. But from the description on Wikipedia, this is what cross correlation does. ...
1
vote
1answer
129 views

What is the significance of first zero upcrossing of a cross correlation?

What is the significance of the first zero up-crossing of a cross-correlation? The signals being correlated are cosines signals with some phase difference. EDIT 1 : Cross-correlation plot attached. ...
1
vote
2answers
592 views

How do I get the phase angle from Cross Correlation?

Im trying to cross correlate two signals in matlab and get the phase difference between the signals. For cross correlation (the idea is to do it without xcorr) I used: ...
1
vote
1answer
150 views

Calculating an impulse response in a stable environment

I would like to estimate the impulse response of a simple environment (room, two speakers, one microphone). I am aware of the issues/limitations of working with "near" LTI systems. That said, I have a ...
5
votes
1answer
500 views

Measuring time delay of audio signals

Before anyone yells at me I fully realize that this question has been asked numerous times. I assure you that I've read through the existing questions and answers but I am still confused about part of ...
4
votes
0answers
40 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 ...
5
votes
1answer
1k 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 ...
5
votes
1answer
129 views

Cross Power Spectral Density of Unevenly Sampled Data

Here's my problem. The input signals $x$ and $y$ will be having the time value aligned with each other. However, the data are not evenly sampled. I would like to calculate CPSD of both signals. The ...
0
votes
1answer
151 views

Find the time lag for a wave

suppose that we have a wave which has some peaks in some indexes like 2,12,25,... and otherwise zero. I want to extract the time lag or lags between peaks of a signal. could anyone help me ?
1
vote
2answers
217 views

Correlation between 2 functions

I have a periodical function $f(x)$ that is sampled in time, at a rate of 1 millisecond. Together with this, I also have a second function $t(x)$. I want to find the correlations between periods ...
2
votes
1answer
230 views

Normalized cross correlation via FHT - how can I get correlation score?

I'm using the 2D Fast Hartley Transform to do fast correlation of two images in the frequency domain, which is the equivalent of NCC (normalized cross correlation) in the spatial domain. However, ...
1
vote
1answer
769 views

Finding periodicity of spikes, matlab

In my time series data, I have often spikes with regular periods. Sometimes, I get two or three different periodical spike sequences (two electrical noise sources), some with T1 seconds period, some ...
2
votes
1answer
90 views

How can I detect clicks/ticks in a wav file?

I have a long recording of a train (here is a small sample) there are a number of clicks as the wheels go over joins in the tracks. I would like to detect the location of these. Looking at the ...
0
votes
1answer
219 views

get amplitude difference via cross correlation?

im currently comparing 2 signals: A = some music B = A + noise and ive implemented cross correlation in frequency domain via complex multiplication to determine the time offset, which works ...
12
votes
2answers
375 views

Finding symmetric regions/patterns in image

I have a set of images representing the mean curvature of a human back surface. What I want to do is to "scan" the image for points which have similar, reflected "counterparts" in some other part of ...
0
votes
1answer
232 views

Is there any example or existing resource for using matlab in audio comparison (cross correlation)?

I am new to MATLAB. I have the audio files A and B, B is recorded using a mic while playing audio file A. The length of file B is different from A. A does not always start from 0 second. My program is ...
2
votes
1answer
262 views

determine background noise level via cross correlation

The setup: Sound is being played by the speaker on the iphone. At the same moment i record sound via the microphone. Obviously the speaker sound will be recorded in addition to all the external noise. ...