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Re: Fourier analysis of the Data with some gaps [message #66027]

Tue, 14 April 2009 09:39

R.G. Stockwell
Messages: 363
Registered: July 1999

Senior Member

<duxiyu@gmail.com> wrote in message
news:55d7a5d9-0fc3-462d-a680-3be22f337271@k19g2000prh.google groups.com...
Thank you for your explanation.
I am very intertesting in the local spectral technique you mentioned.
Could you recommend some references about it?

Best regards,
jdu
**********************

There is a lot. A straight forward Short Time Fourier Transform is
simple and easy to understand. Simply parse the time series into small
overlapping regions and FFT it.

There are wigner type transforms, that in my opinion are very useful
for real data with noise.

There are wavelets (two disctinct branches, you'd want the CWT with morlet
wavelets or perhaps mexican hat wavelets if you are interested in local
spectra.
Orthogonal wavelets are not directly related to the fourier spectrum)

And there is the S-transform, which is combination of STFT and Wavelets,
and has several advantageous characteristics.

http://www.cora.nwra.com/stransform/

cheers,
bob

PS disclaimer, the ST stuff is mine, so I may be a bit biased when I
say it is superior to all other methods for the analysis of transient
quasimonochromatic
signals in geophysical data. :)
Source code is available on that website.

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[Message index]

		Re: Fourier analysis of the Data with some gaps By: R.G. Stockwell on Tue, 14 April 2009 09:39
		Re: Fourier analysis of the Data with some gaps By: duxiyu@gmail.com on Mon, 13 April 2009 23:37
		Re: Fourier analysis of the Data with some gaps By: R.G. Stockwell on Mon, 13 April 2009 09:10
		Re: Fourier analysis of the Data with some gaps By: Kenneth P. Bowman on Mon, 13 April 2009 08:44
		Re: Fourier analysis of the Data with some gaps By: duxiyu@gmail.com on Wed, 15 April 2009 00:36

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