# Questions tagged [cross-correlation]

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### 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 ...
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 ...
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 ...
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 ...
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 ...
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 ...
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; ...
402 views

### Wiener filter yielding negative MSE (and MMSE)

I implement a Wiener filter using the following code ...
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++...
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 ...
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 ...
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 ...
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 ...
559 views

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. ...
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 ...
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 ...
725 views

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}^{...
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 ...
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 ...
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 ...
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 ...
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 ...
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 ...
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 ...
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, ...