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From: "John Garas" <garas@remove.dspalgorithms.com>
Newsgroups: comp.dsp,comp.soft-sys.matlab
References: <ap102a$6ce$1@scotsman.ed.ac.uk>
Subject: Re: DFT of an irregular time-spacing signal
Date: Tue, 22 Oct 2002 19:14:00 +0200
Organization: dsp algorithms
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From one point of view, the DFT (or FFT) is just a mathematical
transformation. You can apply it on any vector of samples and it will result
in another vector of samples. The question is how to interpret the result of
applying the transformation on a non-uniform sampled signal. There are many
multiresolution spectral analysis systems based on calculating the Fourier
transformation of non-uniform sampled signals. If you would like to go into
such systems you might want to start with the following papers and the
references in them:

1) S.K. Mitra, S. Chakrabarti, and E. Abreu, "Nonuniform Discrete Fourier
Transform and its application in Signal Processing", Proc. EUSIPCO '92, Vol.
2, pp. 909-912.

2) J. Garas, and P. Sommen, "Warped Linear Time Invariant Systems and Their
Application in Audio Signal Processing", ICASSP '99. You can get this paper
in postscript here
http://www.dspalgorithms.com/technology/icassp99.html
or in PDF here
http://www.telecom.tuc.gr/paperdb/icassp99/PDF/SCAN/IC991209.PDF

Regards,

John Garas

"Chia C Chong" <Chia.Chong@ee.ed.ac.uk> schreef in bericht
news:ap102a$6ce$1@scotsman.ed.ac.uk...
> Hi there!
>
> I have a signal, y which has irregular time-spacing. I would like to find
> the power spectrum of this signal. Since the signal has irregular
> time-spacing, I guess I can't simply perform the DFT using the fft command
> in Matlab?? If so, what method should I used in order to find the power
> spectrum of y?
>
> Thanks.
> CCC
>
>
>