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Questions tagged [convolution]

Convolution is a mathematical operation on two functions f and g, producing a third function that is typically viewed as a modified version of one of the original functions.

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87 views

Apply LTI filter to incoming signal stream [duplicate]

Typically, when I want to filter a signal with an LTI filter (in this case a low-pass filter), I just convolve the signal with the filter. However, what do I do if I have a stream of data that I want ...
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1answer
391 views

Exponential decaying step response in LTI System

I'm attempting to better understand the relationship between step responses, impulse responses, and convolutions. Say that I have a system where if I apply a constant input, my output decays from a ...
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2answers
407 views

Does the impulse response of a system have any physical meaning?

In other words, what does the impulse response tell us about the characteristics of the system? For simplicity, let's assume we deconvolve a discrete output and a discrete input to obtain an impulse ...
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1answer
831 views

Why a convolution matrix is called a kernel?

According to Wikipedia: In image processing, a kernel, convolution matrix, or mask is a small matrix. I am wondering, why the matrix is called a kernel? Does it has anything to do with kernel ...
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2answers
95 views

Question related to Deconvolution and Fourier Transform

Currently I am completely new to Signal Processing and I am about to kick off a project related to the system identification. The general idea is given a pair of sent and received signals, I have to ...
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0answers
292 views

discrete fourier transform circular symmetry

I was reading digital signal processing. In topic Discrete Fourier Transform, circular symmetry it is said that circular advance is obtained by shifting x(n) in clockwise direction. i.e. to obtain x(n+...
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1answer
45 views

Can cross-c.(x,y) be positive if signals x and y do not share frequencies?

The question is if the cross-correlation of two signals $x$ and $y$ can be non-zero even if $x$ and $y$ do not share frequencies. My approach is the following: The cross-correlation $\rho_{xy}\left(\...
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3answers
359 views

Fast way to calculate a few points in convolution?

Say I have two 1000-point sequences. I can compute the entire convolution fairly efficiently using FFTs (keeping in mind that zeroes have to be padded on to avoid doing a circular convolution). ...
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1answer
193 views

Question about correlation of two signals

I'm working on some practice examples and in one of them I'm asked to find the convolution and the correlation of some signal pairs given. I know that correlation , given two signals x(n),g(n), is ...
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1answer
271 views

Question about convolution of shifted function-simple

I memorized the convolution formula, all good. I started doing examples and in one of them I had to calculate the convolution of a shifted function with another one. I know the property $$H(x)=f(x)\...
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1answer
621 views

How to “scale” the FFT when using it to calculate discrete convolution?

As you probably know, the discrete convolution $ H = F \ast G $ of some $ F \left[ x \right] $ and some $ G \left[ x \right] $ can be calculated using the Fast Fourier Transform (FFT). To do this, ...
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1answer
207 views

Why Filter Kernel is flipped during convolution process? [duplicate]

Why Filter Kernel is flipped during convolution process? What are the consequences if the kernel is not flipped? Note: Filter Kernel means: Impulse response or convolution kernel.
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1answer
895 views

Convolution by differentiation property of convolution

This is the question when i am trying to do it by the deravative property of convolution https://en.wikipedia.org/wiki/Convolution#Differentiation like this Actual answer should come like this $...
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1answer
62 views

Convolution Input/output Units

How come are the units of convolution for LTI system not consistent? $$y(t)= \int_{-\infty}^{\infty} x(\tau)h(t-\tau)d\tau$$ $y(t)$ unit is volt, whereas the RHS has volt.time unit!!!!
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1answer
97 views

Reduce Signal Size to Compare Them

I have multiple experiments and each of them produce several ($k$ for example) binary signals; some artificial example next: I have a metric to compare experiment results but I need vectors of equal ...
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1answer
2k views

Implementing Frequency Domain Convolution in MATLAB (Convolution Theorem)

I'm trying to prove convolution in time domain is same as multiplication in frequency domain but I'm not getting the same answer in matlab. Here is the code:
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3answers
421 views

Minimal number of additions in convolution

The Winnograd algorithm can be used to reduce the number of multiplications in convolution. Is there a known method of reducing the number of additions in convolution?
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1answer
420 views

PDF of a sum of two RVs by convolution of their samples via fourier transform in Excel

I apologies if this is off topic for this site, but I am trying to figure out (and not having much luck) how to get an empirical distribution function of a sum of two random variables given two ...
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0answers
74 views

How to convert multi-band Energy Time Curve (ETC) to Impulse Response (IR)?

I am running my own sound simulator. Now I have obtained the Energy Time Curve (ETC, expressed by energy) by physical simulation, and they are stored in 8 discrete frequency bands (because decay of ...
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1answer
147 views

2D image convolution: when to peform direct convolution and when to perform FFT/multiple/IFFT

I want to convolve 2 images I1 and I2. Let's assume they have the same size. I know 2 methods: 1) Use direct definition of 2D convolution 2) i. Computer FFT of I1 (call it I1_FFT) and FFT of I2 (call ...
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1answer
255 views

3D FFT's and Convolutions using FFTW

I am trying to perform a of convolution 2 3-dimensional vectors using the FFTW3 library in C. My question relates to the order in which the frequency domain appears and if it will make a difference ...
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0answers
25 views

Applying phone-effect on clean speech corpus without spectogram loss

I intend to train an end to end speech recognition engine for phone conversations. Most of the available corpus is crystal clear narrated data, so i'm looking for a way to bring my training data ...
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5answers
466 views

Fast & accurate convolution algorithm (like FFT) for high dynamic range?

It seems that FFT-based convolution suffers from limited floating-point resolution due to evaluating everything around the roots of unity, as you can see in the $10^{14}$-factor error in this Python ...
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2answers
113 views

Would anyone be able to help out with the following discrete convolution question?

I have been trying to attempt this question for quite a while and I am not sure how to approach it. Would anyone be able to help out with the working?
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1answer
67 views

Convolution a 3-D signal with 2-D signal

I have a 3D signal $M(x,y,t)$ and I want to do convolution with signal $G(x,y)$ and $Et(t)$, I mean, how to calculate this Convolution below in Matlab? $$A(x,y,t)=M(x,y,t) \star G(x,y) \star Et(t)$$ ...
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2answers
635 views

Solving a Convolution Problem

I was unable to solve a convolution question.Question is attached herewith. I don't know how to initiate for solving the problem and what is the final expression that prove the convolution of a top-...
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1answer
27 views

measuring how much signal corrupted by passing from a medium [closed]

I am looking for a measure to report how much a signal has corrupted by passing a medium. Suppose we have a signal 2Hz and amplitude ...
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1answer
146 views

Filter design to realize Cauchy product

I come from Computer Science so please pardon for my possibly wrong terminology. I need to design a filter which has coefficients $$h_0, h_1, \ldots, h_n, \ldots \quad\text{such that}\quad h_0 > ...
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0answers
23 views

Recognize irregular repetition of unknown feature (stamps at random locations)

I have an image which is generated by convolution between (1) a simple small patch and (2) larger image composed of localized point-like features (e.g. slat-and-pepper noise, sum of shifted $\delta$-...
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2answers
315 views

Two real time signals convolving

This might be a stupid question but is it possible to convolve two real-time signals together? I know that generally for running convolution you have the IR and the block of the real time signal and ...
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1answer
46 views

Deep learning model for phone recognition - issues with dimension the model

I seem to have some problems understandind how the model described in this paper has been designed This is what is written about the model dimension.. ...In these experiments we used one ...
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1answer
119 views

Is sampling a Fourier transformed signal and fourier transforming a sampled signal the same?

I'm having a hard time understanding an assignment that states: Draw the complex spectrum of the sampled signal $f(t)$ (periodic and continuous). Do this, by first calculating the Fourier ...
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2answers
683 views

Implementing a Band-Pass Filter from Scratch

I am trying to implement a band-pass filter from scratch. Here is an article which I thought explained the nuts and bolts of how to build one; the author combines a low-pass with a high-pass filter (...
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2answers
1k views

Parameters of Gaussian Kernel in the Context of Image Convolution

Hi Everyone i am new at image processing. I copy code from this website, I have image $600 \times 480$ gray scale. What will be the value of standard deviation or $\sigma$? What will be the value of ...
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0answers
176 views

Applying a frequency filter in dB onto an audio wav file in the frequency domain

I am working on a university project consisting of a C program supposed to apply a correction of the isophonic curves to an audio PCM file. So far, I have managed to code the most part of it (read/...
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1answer
458 views

Prewitt operator and central difference?

When taking the gradient of an image one can do $I * \begin{bmatrix}+1 \ 0 \ -1\end{bmatrix}$ (x direction). As I understand this is basically applying central differences in the x direction, $\...
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0answers
83 views

Fastest way to subtract known music tracks from live videogame audio stream

I want to isolate video game "action" sounds from the video game soundtrack. Given all ~20 songs, I'd like to filter them out from any live audio stream during gameplay. What is a fast and robust way ...
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3answers
1k views

Convolution and Deconvolution in C

I understand the theoretical foundations of convolution, but now that I'm trying to program it I'm having some issues conceptually. Say I have two blocks of 64 audio samples each. I also have access ...
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1answer
267 views

Filtering White Noise to Generate Harmonic Signal

I have studied convolutions and filters a long time ago. Today, I am trying to review the basics using some notes of mine, but I am finding difficult to solve easy problems. Since I don't have ...
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1answer
438 views

How to do convolution a 2D signal (some image) and result of convolution of two 1D filters?

Assume a 2-D signal (i.e., some image). Load image and assume it to be signal x. Next assume that instead of having a 2-D filter you have two one D filters $$f_1[n] =\begin{bmatrix}0.25 && 0....
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2answers
86 views

Overall system IR: How to do arithmetic with $\delta$ functions?

When finding the overall system impulse, how to do arithmetic with $\delta$ functions? E.g. \begin{align} h[n]&=h_1[n]\star h_2[n]\\ &=\sum_{k=-\infty}^{\infty} h_1[k]h_2[n-k]\\ &=\sum_{...
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1answer
101 views

Understanding an alternative representation for the difference equation of a FIR filter?

I recently solved a problem which required that I compute the convolution of an input signal with the impulse response of a filter. I got the resulting discrete signal which is verified to be the ...
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0answers
248 views

Deconvolve using divsion of FFT of shifted signal in time domain

I have FFT of two signals. Y=120 , Y1=80 Hz. to convolve in time domain I can convolve them using their ffts. as ...
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2answers
601 views

Using Convolution as Feature Extraction

I am now studying image processing in my spare time. My understanding of convolution is about 'response to a specific filter': When we have a raw image, or raw signal; and a filter, aka kernel; we ...
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2answers
724 views

Why does reversing the order of these two transfer functions give me different outputs?

Consider these two systems: \begin{align} &u\ {\longrightarrow}\boxed{s}{\longrightarrow}{\boxed{\frac 1s}}{\longrightarrow}\ y\\ &u\ {\longrightarrow}\boxed{\frac 1s}{\longrightarrow}{\boxed{...
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1answer
84 views

Applying Image Filtering (Circular Convolution) in Frequency Domain

To filter an image we can: Use a 3x3, 5x5, 7x7, etc. filter, that is convolve the image and the filter in the space domain. Use a FFT on both the image and the filter, multiply them together in the ...
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1answer
618 views

Is periodic convolution same as circular convolution?

I know exactly what is periodic convolution. But i don't know if circular convolution means to be the same thing!
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1answer
910 views

Convolution of Two Kernels [OpenCV]

I've been completely stuck on a portion of my assignment for a few days now. After plenty of searching around, I have been unsuccessful in discovering information that leads me to the correct solution....
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1answer
738 views

How to implement the $\tt conv(x,h)$ in MATLAB without using loop?

I'm trying to calculate convolution of two given vectors in MATLAB without using loop, and of course without the function conv itself, but I can't remove the last ...
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2answers
832 views

Convolution of two large signals in MATLAB

I need help regarding convolution. I am trying to convolve a signal which is $15\textrm{ ms}$ long, and the sampling frequency is $10\textrm{ GHz}$. I need to convolve it with a rectangular pulse, ...