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Re: IDL FFT (spec -> interferogram) [message #30029]

Thu, 04 April 2002 09:03

Paul van Delst
Messages: 364
Registered: March 1997

Senior Member

Randall Skelton wrote:
>
> Hi all,
>
> Having read through all of the FFT posts that google groups keeps, I am no
> closer to understanding why I am unable to transform a spectrum into an
> interferogram using IDL. All of the data files, procedures, and pictures
> of this are at http://tulip.atm.ox.ac.uk/~rhskelto/fft-help/

all your spec data is zero.

>
> The result 'idl_igm' contains twice the number of points (minus 2)
> because of the required reflection about the Nyquist frequency.
> Moreover, the result appears to be modulated (almost like a frequency
> chirp)?

This looks like the correct result to me - i.e. an interferogram of a spectrum. Do you want the
envelope of this?

paulv

--
Paul van Delst Religious and cultural
CIMSS @ NOAA/NCEP purity is a fundamentalist
Ph: (301)763-8000 x7274 fantasy
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[Message index]

		Re: IDL FFT (spec -> interferogram) By: Paul van Delst on Thu, 04 April 2002 09:03
		Re: IDL FFT (spec -> interferogram) By: Randall Skelton on Thu, 04 April 2002 08:32
		Re: IDL FFT (spec -> interferogram) By: Randall Skelton on Fri, 05 April 2002 01:17

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