## circular convolution

Started by in comp.dsp13 years ago 20 replies

I'm perusing the web and I suspect worse case I'll grab a few texts to further assist me, nonetheless, given two sequences ( radar application )...

I'm perusing the web and I suspect worse case I'll grab a few texts to further assist me, nonetheless, given two sequences ( radar application ) - reference and receive of length 1024. It was explained to me that the for linear convolution, I'll pad the sequences with zeros, then compute the FFTs. For circular convolution there's no need for padding. None of this makes sense to me as a re...

## How to perform Convolution in excel?

Started by in comp.dsp13 years ago 5 replies

Hi all, As the subject suggest, I would like to know if anyone know how to perform convolution in excel? In excel only have the Fourier...

Hi all, As the subject suggest, I would like to know if anyone know how to perform convolution in excel? In excel only have the Fourier analysis, but no convolution Function. Thanks in advance. Sulphox

## Circular convolution to Linear convolution.

Started by in comp.dsp11 years ago 1 reply

Hi, I am new to this programming world, and i really need some serious help. I have done a program in which i design a filter in frequency...

Hi, I am new to this programming world, and i really need some serious help. I have done a program in which i design a filter in frequency domain, then i take a CT image, which is a 3d image, read each voxel and make a 1d array. then i equal the number of samples for both the data set. so i have equal samples. then i do convolution using fftw3 library. but what happens is that i am doing circula...

## Do the mathematical inverse and identity elements exist for convolution?

Started by in comp.dsp14 years ago 43 replies

Guys: I'm brushing up the mathematical side of my DSP brain. It's a bit dusty having spent the last few years doing implementation and device...

Guys: I'm brushing up the mathematical side of my DSP brain. It's a bit dusty having spent the last few years doing implementation and device control without regard for the underlying math. I'm trying to satisfy myself that vectors are a group under convolution. I've determined that there's an identity element: For any vector V, V* = V (where * is convolution rather than multipl...

## Convolution and cepstral mean subtraction

Started by in comp.dsp12 years ago 8 replies

It seems to me that cepstral mean subtraction (CMS), which is commonly performed in computer speech recognition system, corresponds to...

It seems to me that cepstral mean subtraction (CMS), which is commonly performed in computer speech recognition system, corresponds to a circular convolution. I am curious what people think about how I'm viewing this and about the possible effects of changing CMS to use a linear convolution. This post turned out very long, so if you're in a hurry please just read from the fourth paragraph...

## Search for Convolution method in JAVA

Started by in comp.dsp13 years ago 4 replies

Hello! I'm searching for a method/class/package in JAVA that implements a linear convolution algorithm between two signals. For example...

Hello! I'm searching for a method/class/package in JAVA that implements a linear convolution algorithm between two signals. For example "public convolution(double[] signal1, double[] signal2)" that convolves signal 1 with 2. I've searched in many webpages, but I've found nothing. I think, I'm serching for any easy method, but I don't know why I can't find it. Somebody can help me? Me ...

## convolution

Started by in comp.dsp12 years ago 9 replies

hi guys.....i am beginner in dsp..... Can somebody tell me the physical meaning of convolution.....wht does it do actually??

hi guys.....i am beginner in dsp..... Can somebody tell me the physical meaning of convolution.....wht does it do actually??

## Convolution with a constant value signal

Started by in comp.dsp10 years ago 11 replies

Hello, In the following A is a real constant value signal and the symbol * denotes the convolution operation. We know...

Hello, In the following A is a real constant value signal and the symbol * denotes the convolution operation. We know that: A*x(n)----Fourier----> A.&(f).X(f), where &(f) denotes Dirac function. however, A.X(0)

## Tutorial on Convolution and FIR Filters

Started by in comp.dsp11 years ago 6 replies

Hi, I have created a three flash program that demonstrate: Discrete convolution Low Pass FIR filters Band Pass FIR filters. It is...

Hi, I have created a three flash program that demonstrate: Discrete convolution Low Pass FIR filters Band Pass FIR filters. It is located here: http://www.fourier-series.com/fourierseries2/convolution.html Brent

## help with convolution and product theorem

Started by in comp.dsp12 years ago 5 replies

hi I'm a bit screwed up by the notation used in fourier transform, on convolution and product theorems. I'm drawing a blank with regard...

hi I'm a bit screwed up by the notation used in fourier transform, on convolution and product theorems. I'm drawing a blank with regard to what's the difference between: f1(t)*f2(t) F1(w)F2(w) [convolution theorem] f1(t)f2(t) F1(w)*F2(w) [product theorem] what's the difference between "f1(t)*f2(t)" and "f1(t)f2(t)" please give one example. Thanks.

## fast convolution crossover/break even point for DSPs, FPGAs

Started by in comp.dsp12 years ago 9 replies

Hi, I was reading up on older threads, and I was wondering if everyone could post their experiences with fast convolution crossover points?...

Hi, I was reading up on older threads, and I was wondering if everyone could post their experiences with fast convolution crossover points? I know that theoretically, if you have a FIR filter with 30-60 taps (depending on the source), it is more efficient resource wise to perform convolution in the frequency domain using overlap add/save. However, can people post what they have learned in ...

## partitioned convolution

Started by in comp.dsp12 years ago 4 replies

Hi Could anyone outline the basic steps for partitioned convolution of audio, im fairly new to dsp, i have realtime FFT convolution in...

Hi Could anyone outline the basic steps for partitioned convolution of audio, im fairly new to dsp, i have realtime FFT convolution in c++ working using overlap and add, but im limited at the moment to an IR, with blocks of input ide like to store the FFT of a larger ir split it into blocks and loop through them in the frequency domain multiplication step if possible. thanks for a...

## convolution code for matlab

Started by in comp.dsp10 years ago

hi.. here i m sending correct convolution code for matlab...%************************************************************************* % ...

hi.. here i m sending correct convolution code for matlab...%************************************************************************* % Convolution of Two signals %************************************************************************** %DKV clc; close all; clear all; x=[1,2,3,4]; %first signal h=[1,2,3,4,5]; %second signal N1=length(x); N2=length(h); X=[x,zero...

## Fast Convolution on Images

Started by in comp.dsp10 years ago 1 reply

I am using 5X5 and 3X3 kernels to convolve with Image. As I know convolution is computational Intensive and I have to convolve many kernels with...

I am using 5X5 and 3X3 kernels to convolve with Image. As I know convolution is computational Intensive and I have to convolve many kernels with my image to achieve the result, the execution takes 2 seconds. I would like to reduce the processing time. When I sequentially convolve kernel with image, the values difference between two sequentially convolution is very less in many places, beca...

## Scaling Factor In Approximating Continuous-time Convolution by Discrete-time Convolution

Started by in comp.dsp11 years ago 3 replies

Hello, I know this may sound a common or even a basic question to many, however I will appreciate if someone can give me insight on this....

Hello, I know this may sound a common or even a basic question to many, however I will appreciate if someone can give me insight on this. I read some of the older posts on related topics but a fraction of doubt still remains. I am trying to find the correct scaling factor for the output of convolution (in MATLAB). I have a signal x[n] of length N. I have a unit-amplitide discrete-time r...

## why do we need Polyphase decimatation filter?

Started by in comp.dsp13 years ago 6 replies

I did a decimator FIR filter simply by doing the convolution only once every M' input sample. for example M=3: feed x0,feed x1, feed x2,...

I did a decimator FIR filter simply by doing the convolution only once every M' input sample. for example M=3: feed x0,feed x1, feed x2, convolution, feed x3,feed x4, feed x5, convolution, feed x6,.... Then I find many people talk about polyphase decimation filter, I wonder if it is more efficient than what I'm doing? What is the differrence? thanks mary

## fastest cyclic convolution algorithm

Started by in comp.dsp13 years ago 5 replies

Hello everyone: First of all, thanks to all those who have posted before and for saving the archives. As you know this is my first post here. ...

Hello everyone: First of all, thanks to all those who have posted before and for saving the archives. As you know this is my first post here. I searched the archives by terms and by circular convolution but did not find anything, hope I didn't miss a post. You see, I'm trying to implement a parallel cyclic convolution algorithm and was wondering if someone can point out the fastest cyclic con...

## DFT circular convolution

Started by in comp.dsp12 years ago 2 replies

hello everybody!! can anyone tell me in calculating circular convolution using DFT what will happen if i use two different length...

hello everybody!! can anyone tell me in calculating circular convolution using DFT what will happen if i use two different length signal? suppose one is of 4 point and the other is of 3 point then what will be the system?i have to do both 4 point DFT?or 4+3-1 or 6 point DFT as like linear convolution... plz help me out.. shatila

## How different is the OVERLAP and ADD method from linear convolution

Started by in comp.dsp13 years ago 2 replies

I refer to the method of overlap and add way of performing convolution of large input signals given in proakis. My question is, How is this...

I refer to the method of overlap and add way of performing convolution of large input signals given in proakis. My question is, How is this method of convolving the impulse response with the large input signal by dividing it into small blocks different from the normal way of convolution where we use the conv() function? I tried out the method in MATLAB and both gave the same result. But, I ...

## Image FFT Convolution - C++/VC++ source code

Started by in comp.dsp11 years ago 2 replies

I'm looking for a simple (need not be very efficient) VC++/C++ library that does the image (png) convolution, 2D FFT. I would like to develop a...

I'm looking for a simple (need not be very efficient) VC++/C++ library that does the image (png) convolution, 2D FFT. I would like to develop a image search feature (http://www.dspguide.com/ch24/6.htm) with a VC+ + based GUI around it. http://www.codeproject.com/KB/graphics/ImageConvolution.aspx does have the convolution feature but not FFT. Anybody gone through the same requirement? Thank...