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Subject: Re: How to zoom into a certain part of FFT?
Date: Tue, 20 Nov 2007 15:03:39 +0000 (UTC)
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Yopu can actually zoom using the spectrum scope provided in 
matlab.  Just the menu bars are hidden.  To view the menu 
bars type the following commands

>> set(0,'ShowHiddenHandles','On')
>> set(gcf,'menubar','figure')


Cheers,

Chris


"Vista" <abc@gmai.com> wrote in message 
<f5sk5g$qmm$1@news.Stanford.EDU>...
> Hi all,
> 
> Suppose I have a signal f(t), t is in [0, +infinity).
> 
> And I have its spectrum F(w).
> 
> Let's say I found out that its main spectrum has 99.9% in 
[-B, B].
> 
> So I truncate/extract out the portion of F(w), for w in [-
B, B], and 
> discretized the interval into small grids with step size 
deltaB.
> 
> And I then do the inverse FFT on the above samples of F
(w), let's call the 
> inverse FFT reconstruction f_hat.
> 
> Which part of f(t) does this inverse FFT f_hat represent?
> 
> If I want to zoom into a certain part of f(t), how can I 
use inverse FFT to 
> do that?
> 
> Let's say I only need [a, b] where 0<a<b< infinity, in 
the time domain,
> 
> I only need to visualize the f(t), for t in [a, b],
> 
> how do I sample F(w) and do the inverse FFT?
> 
> -------------------------
> 
> More generally, I am actually thinking of desing 
a "spectrum analyzer" with 
> zoom-in feactures:
> 
> as you can see, first do a coarse level inverse FFT to 
gain a big picture of 
> the f(t) curve, and then allow user to zoom into a 
particular part of the 
> f(t) curve and display it with higher resolution of IFFT.
> 
> How to do all of these?
> 
> Thanks a lot! 
> 
>