Sign in

username:

password:



Not a member?

Search matlab



Search tips

Subscribe to matlab



matlab by Keywords

Atanh | Autocorrelation | Bandpass Filter | C++ | Conv | Database | Deconv | Excel | FFT | Filter | Filtering | FIR | Fourier Transfrom | FSK | Gaussian Noise | Haykin | IFFT | Image | Java | LFSR | LMS | LPC | MEX | OFDM | QPSK | Radix | Random | Sampling | Segmentation | Simulink | Visual Basic | Waveform | Wavelet

Ads

Discussion Groups

Discussion Groups | Matlab DSP | Convolution Problem

Technical discussion about Matlab and issues related to Digital Signal Processing.

  

Post a new Thread

Convolution Problem - Fergyanto E Gunawan - Sep 18 7:08:00 2001



Dear All,

As we know that we can solve the convolution integration by FFT as follow

y(t) = x(t) * h(t) = ifft(fft(x).*fft(h)) (1)

That multiplication just same with

y(t) = X h (2)

where X = Circulant matrix of x.

Using Eq.(1), usually y(t) contain small amount of imaginary part. My questions
are:
1. How to minimize that imaginary part?
2. How to measure the accuracy of convolution by FFT. Regards,

------------------------------------------------

Fergyanto E Gunawan
Toyohashi University of Technology, Japan

------------------------------------------------






(You need to be a member of matlab -- send a blank email to matlab-subscribe@yahoogroups.com )

Re: Convolution Problem - kiran jayanty - Sep 18 20:27:00 2001

use

y(t) = Re( ifft ( fft(x).* fft(h) )) ;

this takes in only the real parts...

to test the accuracy, plot the results from both methods and check for degree of similarity.

hope that helps.

Kiran-----------------------------------------------------------

Address: Ph :Home:(512)9969613
Kiran Jayanthi, Cell :(512)7436676
#8617 Spicewood Springs Road, Off:(512)2313016
Appt#379, Email:k...@cadence.com
Austin, TX 78759 j...@hotmail.com
---------------------------------------------------------
From: Fergyanto E Gunawan
To: m...@yahoogroups.com
Subject: [matlab] Convolution Problem
Date: Tue, 18 Sep 2001 16:08:37 +0900
Dear All,
As we know that we can solve the convolution integration by FFT as follow
y(t) = x(t) * h(t) = ifft(fft(x).*fft(h)) (1)
That multiplication just same with
y(t) = X h (2)
where X = Circulant matrix of x.
Using Eq.(1), usually y(t) contain small amount of imaginary part. My questions are:
1. How to minimize that imaginary part?
2. How to measure the accuracy of convolution by FFT.
Regards,
------------------------------------------------
Fergyanto E Gunawan
Toyohashi University of Technology, Japan
------------------------------------------------

Get your FREE download of MSN Explorer at http://explorer.msn.com


(You need to be a member of matlab -- send a blank email to matlab-subscribe@yahoogroups.com )