comp.lang.idl-pvwave archive: archive

Home » Public Forums » archive » Re: Dynamic Spectrum

Show: Today's Messages :: Show Polls :: Message Navigator
E-mail to friend

Re: Dynamic Spectrum [message #60587 is a reply to message #60578]

Mon, 02 June 2008 09:16

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

Senior Member

<duxiyu@gmail.com> wrote in message
news:b89c97e8-2b45-4507-a70b-0f71cdb91a8e@p25g2000pri.google groups.com...
> Dear all,
>
> I have a set of data and their measued time.
> I want to get the similary Dynamic Spectrum which is shown in
> http://urap.gsfc.nasa.gov/www/reiner/spectra.html.
> Is there any IDL procedure to get the Dynamic Spectrum?
>
> Best regards,
> Du Jian

Hi Du Jian,
here is a link to a page that has IDL code to do a similar thing.

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

The file you would need is s_trans.pro, here is the direct link:
http://www.cora.nwra.com/~stockwel/rgspages/S-Transform/s_tr ans.pro

Here is a simple example:

ex_len = 512
ex_time = findgen(ex_len)
ex_freq = 5;ex_len/16
ex_ts = cos(2*!Pi*ex_freq*ex_time/ex_len)
ex_ts = cos(2*!Pi*(ex_len/5+2*ex_ts)*ex_time/ex_len)
; crossed chirp example commented out
;ex_ts = cos(2*!Pi*ex_freq*ex_time*(1+2*ex_time/ex_len)/ex_len)
;ex_ts = ex_ts + reverse(ex_ts)
!P.multi=[0,1,2]
plot,ex_ts,xtitle='Time (units)',title='Time Series [h(t) = cos(cos(wt))]'
s = s_trans(ex_ts,/samp, /AMPLITUDE,verbose=verbose) ; returns structure,
amps only returned
nlevels = 14
levels = findgen(nlevels)/(nlevels-1)*1.5

contour,s.st,ex_time,s.freq,levels=levels,/fill,xtitle='Time (units)', $
ytitle='Frequency (1/unit)',title='Amplitude of S-Transform'

end

Cheers,
bob

Report message to a moderator

[Message index]

		Re: Dynamic Spectrum By: pgrigis on Tue, 03 June 2008 06:24
		Re: Dynamic Spectrum By: russell.grew on Mon, 02 June 2008 17:20
		Re: Dynamic Spectrum By: R.G. Stockwell on Mon, 02 June 2008 09:16
		Re: Dynamic Spectrum By: jdu on Mon, 02 June 2008 06:17
		Re: Dynamic Spectrum By: lasse on Mon, 02 June 2008 02:59
		Re: Dynamic Spectrum By: duxiyu@gmail.com on Mon, 02 June 2008 02:23
		Re: Dynamic Spectrum By: lasse on Mon, 02 June 2008 01:39
		Re: Dynamic Spectrum By: David Fanning on Sun, 01 June 2008 20:44

Previous Topic:	Re: Subset image by shape file
Next Topic:	ENVI Classification Image to ROIs

-=] Back to Top [=-

[ Syndicate this forum (XML) ] [

] [

]

Current Time: Fri Oct 10 04:46:45 PDT 2025

Total time taken to generate the page: 0.55999 seconds