DSP board for ISA or EISA ?

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2 total messages Started by Jim M. Sharpe Mon, 20 Aug 1990 14:25

#917

Author: Jim M. Sharpe
Date: Mon, 20 Aug 1990 14:25

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It seems to me that this was discussed a couple of months ago, but I didn't
need one then, so I wasn't paying much attention. 

I'm looking for a plug in DSP board for a 486 system running DOS.  I'm not picky
about which processor.  Price and software support are the primary selection
factors.

Initially we are only needing the board for a 1024 point FFT, has anyone seen
any special purpose FFT cards?


--
Jim Sharpe / jms@spatial.com

Flat Top Windows

#919

Author: Gregory Harrison
Date: Fri, 24 Aug 1990 13:34

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Hi: 
	are you familiar with FLAT TOP WINDOWS?  Applied to an FFT, I
believe that they greatly reduce the scalloping loss.  The way I understand 
it is that when a frequency component is reflected in the FFT generated
spectrum, unless the frequency is directly aligned with the frequency
corresponding to an FFT bin, there will be a loss associated with that
frequency's reflected power.  At a Spectral Dynamics seminar, someone
mentioned that poeple are using the flat top window more and more, because
it minimizes the power loss for signals that aren't directly on top of a bin.
This seems to correspond with a minimum scallop loss as presented in Frederic
J. Harris' fine paper "On the Use of Windows for Harmonic Analysis with the 
Discrete Fourier Transform", Proc. IEEE, V66 No. 1 Jan 1978.  Supposedly, 
Harris also came up with the flat top window, but I'm not sure.  Do you have
any more information that you could please relay?

Thank You,
Greg Harrison
GE Daytona

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