Stack Exchange Network

Stack Exchange network consists of 174 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.

Visit Stack Exchange
Join us in building a kind, collaborative learning community via our updated Code of Conduct.

The tag has no usage guidance.

2
votes
0answers
29 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 ...
0
votes
0answers
16 views

On the confidence intervals of matrix autocorrelation

Considering the case of signal autocorrelation in 1D, I've read that the distribution of the correlation coefficients $r$ of a white noise (independent and identically distributed random variable) ...
0
votes
1answer
32 views

How to find shift between two signals with Cross correlation?

I have calculated the cross-correlation function between to waveforms. I would like to find the shift between the two waveforms from the peak of the cross-correlation function. I am not really sure ...
0
votes
0answers
37 views

Find the best (seamless) looping points in an audio signal

I have a mono signal x[n] sampled at 44.1 kHz (a single sustained note of an instrument) with Attack, Decay, Sustain, Release, that lasts about 10 seconds (the ...
0
votes
2answers
49 views

Why does the addition of noise improve coherence between two signals?

Taking a simple example of the coherence between two signals, each composed of two sinusoids of frequency 100 and 200 Hz, I expect the coherence to show two peaks in the spectrum located at precisely ...
0
votes
1answer
58 views

Trouble with time-syncing two radio signals using cross-correlation

I posted a similar question a while ago here (I'm posting this follow-up since I'd like to focus more on cross-correlation now). I have a setup where I have two software-defined radios connected to ...
1
vote
0answers
53 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 ...
0
votes
1answer
29 views

Why is the correlation of two random markov chains so large?

A very simple python code shows that the correlation coefficient and spearmann rank between two datasets of uniform random numbers drops proportionally to the square root of the number of points in ...
2
votes
2answers
106 views

How can I align these two signals? Cross correlation isn't working properly

I have two radios sampling simultaneously, and I am trying to time-align their two signals (they will always start sampling at slightly different times with random delays due to hardware differences). ...
-1
votes
3answers
80 views

The explanation of $|R_{XY}(\tau)| \le \sqrt{R_{XX}(0)R_{YY}(0)}$

If i said the explanation of $|R_{XX}(\tau)| \le R_{XX}(0)$ is that in the time domain,any signal wave are the same as itself when it doesn't shift.Then what is the explanation of $|R_{XY}(\tau)| \le ...
1
vote
1answer
35 views

Group delay using cross correlation?

An input signal + (thermal) noise travels through a channel and can be measured at its output. Is it possible to use cross correlation between input and output signal to measure group delay? If not, ...
0
votes
1answer
97 views

No cross-correlation between same signal recorded using two different microphones

I've recorded the same audio signal using two microphones located at the same approximate location. However, when checking the cross-correlation using MATLAB (using the xcorr function) it is ...
0
votes
0answers
60 views

Resolving periodic components from time-series data

From the FFT, I know that my time-series data contains a component with some periodicity at 5 Hz. Harmonics are also present because the component is both nonsinusoidal and has variable timing (i.e., ...
0
votes
0answers
54 views

PHAT filtering for cross-correlation yields wrong results while simple cross-correlation does OK (Python)

I work with two signals, the second being perfectly delayed and attenuated, with no reverberation. I implemented cross-correlation algorithm, which yields me these results: Here is my code for these ...
0
votes
0answers
46 views

Edge effects in cross-correlation

This is a follow-up of this question. The problem explained in the linked question has been in part solved by the mean of a windowing function. But my cross-corrleation still exhibits strong edge-...
0
votes
1answer
62 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) +...
0
votes
1answer
17 views

Investigating correlation for unequal signal lengths

I have measurements from two tablet sensors. The first sensor measures the touch pressure applied to the tablet and the second sensor is the acceleration of the tablet (in z direction). The sensor ...
0
votes
1answer
84 views

Convolution and cross-correlation on 2D image (Example)

I have read that convolution and cross-correlation are the same thing, but convolution flips 180 degrees (images), or time reverses (sequences) the kernel, before performing the elementwise ...
0
votes
2answers
85 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 ...
1
vote
1answer
42 views

Parabolic fiting for sub-sample precision

I am performing cross-correlation between two double[1024] arrays. I want to track the correlation's maximum with sub-sample accuracy, so I decided to implement parabolic fitting to my code. I used ...
0
votes
1answer
65 views

Windowing a signal for FFT

I am actually working on a project involving the cross-correlation of two signals. My cross-correlation code is working fine, but I suspect that I should apply a window to my data set in order to ...
2
votes
1answer
97 views

Cross-correlation, sharp peak at 0?

First of all, I have to stress that I am not a professional of coding, no more than a professional of signal processing. I am a chemist that happen to be working on a project involving both. So in ...
0
votes
2answers
79 views

Interpreting this plot cross-correlation

I have an input signal $x(t)$ that is a white Gaussian random signal with mean 0 and variance 1. The signal $y(t)$ is the output of a linear filter with impulse response $$h(t) = |\operatorname{sinc}(...
2
votes
1answer
98 views

How to calculate a delay between two signals in frequency domain?

Calculation of a delay between two signals is generally done by finding the maximum in the cross-correlation of the two signals (in time domain): $$ \tau_{delay} = \arg\max_\limits{t}(f(t) \star g(t)) ...
0
votes
1answer
58 views

Is there any relationship between the convolution and cross-correlation of two signals? [duplicate]

There are two square 2-D signals with the same size $m \times m$, if the result of convolution of those two signals is first picture, And the result of cross-correlation of those two signals is second ...
0
votes
0answers
24 views

Relationship of the cross correlation and the amplitude of the signal

I would like to characterise the maximum amplitude $|x(t)|$ (or similar quantity $|x(t)|$ or $|x(t)|^2$) of the following linear system $$ x(t) = \int_0^\infty K(t')S(t-t')dt',$$ where $ S(t) $ is ...
1
vote
0answers
49 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'...
0
votes
0answers
16 views

Issue in template matching code

code is supposed to take the input image, extract the objects, then overlap circle masks of decreasing radius (r=64,.....1) on each object. A histogram of the no. of white pixels that coincide with ...
0
votes
2answers
57 views

How to estimate ALL time-delays across MULTIPLE signals?

Imagine there are 100 recordings of the same signal or pattern, but those recordings are not properly aligned with each other in time. In other words, each sample has some unknown time delay in ...
2
votes
2answers
65 views

How to calculate time of arrival using room impulse response

I need to find the timestamp of arrival of a particular signal at a receiver location within a room. The known parameters are the room impulse response h for a ...
1
vote
1answer
151 views

DoA estimation using microphone array

I am using an array of 4 microphones in a square formation. My goal is to estimate the direction (azimuth only) of incoming speech sound. The array looks like this: I have recordings from the array ...
0
votes
0answers
13 views

Average delay in skewed cross-correlation function with phase lag zero, plus example

I am calculating the cross-correlation function (CCF) between two digital signals in the following way: $$CCF(τ) = r(M(t),N(t+τ))$$ where $r$ is the Pearson correlation, $M$ and $N$ are two signals, ...
0
votes
3answers
262 views

Cross correlation, when two signals are “uncorrelated”?

Definition of cross correlation is $$ \int_{\mathbb{R}}s_1^*(\tau)s_2(t+\tau)d\tau $$ I wonder using such definition, when two signals are not correlated? My guess is the following... defining $$ s_{...
0
votes
2answers
49 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
254 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: ...
0
votes
0answers
66 views

Subsample phase correlation method for time delay estimation / image registration

I'm trying to implement the subpixel registration method discussed in this paper, towards estimating time delay in a 1d signal. In a nutshell, to find the shift between two vectors $f$ and $g$, one ...
3
votes
0answers
38 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 ...
0
votes
0answers
32 views

synchronizing sender's and receiver's signal using cross-correlation

I'am attempting to synchronize the timing instance of the sender's and receiver's signal in a communication channel, i.e trying to find the lag(timing delay-as the clocks are not synchronized) at the ...
0
votes
1answer
122 views

Cross-correlation - Why is there a complex part after FFT/IFFT when deleting the mirrored part of the spectrum?

I want to detect a special shape in my time series and I apply an matched filter using cross-correlation to increase the SNR. ...
0
votes
1answer
259 views

Image Cross-Correlation interpretation

I'm working on this idea of choosing best cover image from given db for image steganography(hiding secret image inside cover). I've started with calculating cross-correlation matrix between images in ...
1
vote
1answer
190 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
0answers
63 views

IR estimation with cross correlation

I have the input and output of white-noise signal. My overall goal is to estimate the impulse response of a system through cross correlation of my $x$ and $y$. I am doing this through MATLAB for ...
0
votes
0answers
45 views

Estimate phase response of unknown system by using cross correlation

I am currently writing a script in MATLAB in order to try if I can estimate the phase response of an unknown system by using cross correlation. I am doing this by applying several pairs of sine-waves ...
0
votes
0answers
47 views

Web Audio convolver to detect power and phase of a known but noisy signal?

I need to determine the power and phase shift of a known audio signal that is reflecting in a chamber and I would like to do it using the Web Audio API. From a dated signal processing background, I ...
0
votes
0answers
32 views

equivalency between cross-spectrum and covariance of band-limited analytic signals

I have worked out through experimentation that for phase-shifted pure sinusoids $x(t)$ and $y(t)$ of frequency $f$, the (complex) cross-spectrum $\Gamma_{x,y}(f)$ is numerically equivalent to the ...
1
vote
1answer
57 views

Why MATLAB only allows cpsd and mscohere between vectors with the same length?

I am studying the applications of finding coherence in the frequency spectrum between two signals for pattern recognition. I have a recording that is way longer than the sampled signal that I want to ...
3
votes
2answers
272 views

Interpolating the peak of a cross-correlation using a centroid

Forgive me if this question is poorly worded, I'm not sure if centroid is the word to use here. Say I want to interpolate the peak of a cross-correlation function in order to get sub-sample delays. I ...
0
votes
0answers
179 views

Check similarity between 2 signals

Even if this topic is quite common here I still haven't found a complete answer to my problem. I have a script python that creates 2 sampled signals. The first signals is a sawtooth waveform and the ...
1
vote
2answers
170 views

Why do we use white noise to estimate echoes?

I'm interested in the case where I have received a signal as a composition of three echoes of the transmitted signal $x[n]$ (each echo has its amplitude and time delay). I know that in order to ...
-1
votes
1answer
58 views

Synchronizing 2 seperate speech audio signals

I have two speech signals: one with a man reading a passage, and one with a woman reading the same passage. I want to synchronize these signals so that, for each word, their readings line up. The ...