Questions tagged [cross-correlation]

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How to interpret cross correlation output?

The output of cross corelation shows the similarity between the two signals. But in what respect is there a similarity? I didn't quite understand how I should interpret the output. How should I ...
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CIR calculation from SDR data: RTL-SDR, bladeRF

We’re developing a prototype using bladeRF and various Python scripts for processing IQ samples. The system works mainly around 2.4 GHz frequencies: Wi-Fi and Bluetooth. One of the needed functions is ...
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3 votes
3 answers
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How to decide whether a recording contains a signal of interest?

I am currently implementing an acoustic communication system in Matlab. For synchronization purposes, every transmission contains an upchirp preamble. The receiver uses cross-correlation to find the ...
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2 votes
1 answer
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Using cross-correlation of spatially shifted data to gain geometric information

Cross-correlation is usually used to estimate e.g. lags between signals that are detected by different sensors at different times. In my case, the situation is slightly different in that I measure ...
4 votes
1 answer
145 views

Estimation of the attenuation of two waves on a linear sensor array

Context and objective I am trying to estimate the attenuation coefficients ($\alpha_u$ and $\alpha_v$) of two waves ($\overrightarrow{u}$ and $\overrightarrow{v}$). These waves propagate on a linear ...
1 vote
2 answers
160 views

Detecting a known alarm signal in an audio stream

I am going to detect alarm sounds (like from a fire detector) in a live stream. (I have asked similar questions here before, I'm now at the stage of actually doing it). I will not really want to ...
0 votes
2 answers
53 views

Extract a signal from noise, so I can view noise spectrum only?

I have a perfect modulated signal. I have the same signal but with noise, this noise is from non linear amplification. Is it possible, to extract the clean signal so it's just leaving the noise? The ...
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1 vote
2 answers
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Autocorrelation & Cross-Correlation -> Main uses in DSP??

Please help understanding the DSP usage of Autocorrelation & Cross-correlation It seems this is strongly linked to calculating phase offsets, frequency offset for carrier recovery, symbol timing ...
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8 views

Preamble detection Threshold calculation [duplicate]

can anyone recommend a good article where I can read how to correctly calculate the threshold for detecting the presence of preamble at the output of a matched filter?
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3 votes
1 answer
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Cross Ambiguity Function Peak Width

I am trying to plot the Cross Ambiguity Function of two OFDM signal (1024 subcarriers) reflected from two targets, which are separated by 30m. The problem I am facing that the CAF peak width at the ...
0 votes
0 answers
23 views

Covariance of 2D cross correlation result

I am trying to align two 2D signals with one unique correct alignment. After applying 2D cross-correlation on the signals I get results such as these: bad/degenerate peaks: good peaks: decent peak: ...
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1 answer
70 views

Find offsets of two audio files with several sections in common

I have two audio files that have mostly identical* content, most of which is just people talking. A typical example would be two files, each approximately an hour long, in which ~55 minutes of the ...
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5 votes
3 answers
182 views

Cross-correlation seems defined backwards

Suppose $f$ and $g$ are real. Why $$ C(\tau)=(f\star g)(\tau) = \int_{-\infty}^{\infty} f(t) g(t + \tau)dt \tag{1} $$ and not $$ C(\tau)=(f\star g)(\tau) = \int_{-\infty}^{\infty} f(t) g(t - \tau)dt\...
0 votes
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Is maximum cross-correlation achieved at the origin?

Let $x[n]$ and $y[n]$ be two DT random signals with $x[n]\xrightarrow{\mathcal{H}}y[n]$ through some system $\mathcal{H}$ that is deterministic yet unknown.\ Define both the autocorrelation and cross-...
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2 votes
3 answers
299 views

Delay/Lag calculation using cross correlation in frequency domain

I need to compute cross correlation of two signals using frequency domain. Hence, I am using the below equation for calculation. max(IFFT(FFT(a)*conj(FFT(b)))) ...
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Cross-correlation threshold for phase and time synchronization

I have a question regarding correlation-based synchronization. In particular, I'm interested in learning more about how to set a threshold. I currently use a percentage (around 90%) of maximum ...
1 vote
1 answer
88 views

Resolution of phase measurement using cross Correlation

The setup is the following: I am using a RedPitaya board to measure the phase shift of two input signals. These input signals will sweep logarithmically from 1kHz to 100 kHz in 10 seconds. Currently, ...
1 vote
1 answer
131 views

Cross-correlation maximum in frequency domain

I need to compute the complex cross-correlation between two signals a and b and the take only the maximum value of the cross-correlation, regardless of the lag time where this occurs. I can do it ...
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Synchronization for busty signals by correlation methods

I'm trying to reuse standard synchronization algorithms for phase(Costas) and Time (Polyphase Filter bank) for receiving bursty signals. The bursty signals are transmitted every 5 seconds. The signals ...
1 vote
1 answer
38 views

Can multiple cross-correlation be expressed in terms of multiple Fourier transforms?

A post explains that the cross correlation of two signals can be given by $$\mathcal{F}^{-1} \left\{\mathcal{F}\left\{x(t) \right\} \mathcal{F}\left\{y(t) \right\}^* \right\}$$ Does this generalize to ...
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1 vote
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Linearity of the system with Pearson correlation sliding window

I have a sampling system that consists of linear and non-linear components(analog filters, ADC, CPU, and so on). I made some HW changes and I want to verify that the linearity was preserved. My method:...
0 votes
1 answer
26 views

What transformation preserves first term and averages the opposite conjugates?

I can't figure not find any reference on what is this transformation (what $X$ represents in relation to $A$). If $A=[a_1+jb_1, a_2+jb_2, a_3+jb_3, ..., a_n+jb_n]$, $X$ is defined as:$$X=\left[j b_1, \...
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2 answers
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Confusion In DC power,Average Power,Ac Power and total Power

These are Things I studied. $ E[X]:-$ THis gives us Average value or Dc value $E[X^2]:-$Total power $\sigma^2=E[X^2]-E[X]^2$:-Ac power From Autocorrelation $R_x(0)=E[X^2]$--Total power And $ \lim_{x\...
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Y axis Component of Rxy in MATLAB

I calculated the $R_{xy}$ by cross-correlating $x(n)$ and $y(n)$. Now, in the MATLAB command window, I wish to construct the Y-axis component of $R_{xy}(n)$. I'm not sure how I'm going to do it. Is ...
0 votes
0 answers
19 views

How can I generate X Axis componant in R_xy in MATLAB?

Let's say I have cross-correlated $x(n)$ and $y(n)$ and got the $R_{xy}(n)$. Now if I want to generate the x-axis component of $R_{xy}(n)$ in the command window of MATLAB. How can I do that? is there ...
0 votes
1 answer
58 views

Failing to use Cross-Correlation to find position of measurement sequence in data-stream

Recently I used two measurement systems to record a quantity. I made sure both use the same sampling frequency. One system was recording continuously while the other one was operated to only record ...
0 votes
0 answers
100 views

Computing Phase Difference Between Two Channels from SDR

I'm trying to compute the phase difference between two channels of a software-defined radio. I'm providing code for two different methods that I'm trying below. In both cases, I'm transmitting a pure ...
1 vote
2 answers
227 views

Difference between reference and measurement signal?

Which differences can we find on various signals? We assume that we have a reference signal (determined theoretically) and measured signal. Which methods exist for determining the similarities ...
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35 views

2D space and 1D time evolution of a random field

I also asked this on math stack-exchange, but it is also relevant for the signal processing community. I want to develop a 2D random field and its change with time with constant velocity. My process: ...
0 votes
0 answers
107 views

MATLAB filter and conv Functions

I'm trying to get familiar with MATLAB's filter and conv functions. To start, I created a signal that was 1000 zeroes followed by a 13 sample long Barker code. I then convolved it with the same Barker ...
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43 views

Auto/cross correlation for data set with multiple realizations

Context For an assignment, I need to find the correlation matrix of a dataset with 100 random variables and 1000 realizations for each. (It's a stock market example). Problem I don't understand how ...
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0 votes
1 answer
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xcorr MATLAB is not giving accurate result in case of noisy signals

I've a signal $x(n)$. I've generated its delayed copy named $x1(n)$ and applied xcorr function of MATLAB to find out the delay. It gives accurate delay. Now I ...
1 vote
1 answer
870 views

scipy cross-correlation: interpretation

I want to compute the phase shift between two 1-D signals of same frequency, but before I'm trying to compute the time shift between. The cross-correlation function seems to be ideal for that but I'm ...
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Finding the Right Image-Matching Algorithm for Brightfield Microscopy Data

I work predominantly on single-particle-localization algorithms for microscopy data, but we're working to implement a few different methods to extend our tracking methods nicely into the z-axis. One ...
2 votes
1 answer
64 views

Why is peak of the signal taken as the Time Delay

I was reading this research paper titled 'The generalized Correlation Method for Estimation of Time Delay' by C. Knapp and G.C. Carter. They develop an ML estimator and in the introduction mention ...
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-1 votes
1 answer
223 views

Relation between bandwidth and amplitude of auto correlation of chirp signal

I am trying to understand the properties of chirp signals and their characteristics. I plotted the autocorrelation of a chirp signal in MATLAB. How can I compute the relation between the amplitude of ...
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0 votes
1 answer
151 views

Estimate the time delay of two signals

I am having 2 sets of data data1 and data2 .I wanted to find the delay between the two datasets. Assume data1=[1 2 3 4 5 6 7 8 9 10] and data2=[0 0 0 0 1 2 3 4 5 6].From the data I know that, data2 is ...
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2 votes
1 answer
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Method to generate binary sequences with desired cross-correlation and autocorrelation properties

I am looking for a method to generate two binary sequences of length $N$ with the following properties: Very good cross-correlation for all shifts. Good enough autocorrelation for all shifts except ...
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1 vote
1 answer
65 views

RF-Chain Signal Delay for Sensor Switching

Lets have a RF-chain as above with system bandwith from HP corner to the green line say 1 MHz. The signal accumulates delay as it passes through this analog chain, and due to it being non-liner filter ...
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-1 votes
1 answer
232 views

Extraction of the phase lag form cross-correlation function

I would like to find out the phase offset that my signal contains at the receiver side. For this, I use the cross-correlation function, where I cross-correlate signal before and after matched filter. ...
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1 vote
1 answer
55 views

How does a correlation receiver ensure which transmitted data does a user see?

Hello! I understand that using correlation, one can set up a system wherein multiple users can transmit at the same time using the same channel. And theoretically, I understand that if the correlation ...
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1 vote
1 answer
282 views

Real Data Complex Transfer Function using H0, H1, H2 Estimators

BACKGROUND: This question is attempting to consolidate material discussed in two previous topics. These are: Understanding the H1 and H2 estimators @Pontus S Frequency-domain deconvolution: "...
1 vote
1 answer
295 views

Comparing spectrogram similarity over time

I have a data set of spectrograms from moving audio recorders. As the recorders get closer, I expect the spectrograms to become more "similar". I expect this "similarity" to be a ...
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0 votes
1 answer
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Difference between cross correlation definitions (signal processing / random processes)

I'm trying to understand the similarities/differences between the following definitions for cross correlation) Signal Processing: (or it's discrete equivalent) $$R_{XY}(\tau) = \int_{-\infty}^{+\infty}...
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2 answers
282 views

Which algorithm could be used to compare two waveforms from an oscilloscope in XY mode?

I would like to receive some hint as to which algorithm could be used to compare two waveforms from an oscilloscope in XY mode, as shown in the image: Note that the image shows a percentage ...
2 votes
0 answers
54 views

Blind TDOA Estimation

I am not EE or DSP engineer, however I am working on a project that uses TDOA estimation for location finding. I am able to get the localization algorithm working using cross correlation to estimate ...
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Cross-correlation estimation in MATLAB using a method similar to pwelch for the PSD

Is there a function in MATLAB to estimate the cross correlation function of two wide-sense stationary signals (or the autocorrelation of the signal with itself) in a way similar to the estimation of ...
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1 answer
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What is the difference between Goertzel algorithm and cross correlation in time

Im reading https://en.wikipedia.org/wiki/Goertzel_algorithm, when we want to discover the amplitude of a some frequency in a given signal what is the difference between applying Goertzel algorithm and ...
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Can cross correlation be used to see if filtering of a signal has changed it too much?

I am filtering a signal, and want to check if I am not over filtering it. I am doing a low pass filter, for a signal of input frequency of 512Hz, first with 250Hz pass band, then )I was intending to ...
1 vote
1 answer
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Impulse response $h[n]$ from input and output signal using cross correlation on Matlab

I have two signals on Matlab, one being input and the other output. I want to know if taking the cross correlation of these signals would give me the impulse response?And if so, will taking the ...

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