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From: todd@appmag.com (Todd Day)
Newsgroups: sci.electronics,comp.dsp
Subject: Re: A question about the Nyquist theorm
Message-ID: <1991Feb28.084837.7506@appmag.com>
Date: 28 Feb 91 08:48:37 GMT
References: <20408@shlump.nac.dec.com> <625@ctycal.UUCP> <11515@pasteur.Berkeley.EDU>
Reply-To: appmag!todd@hub.ucsb.edu
Organization: R&D, Applied Magnetics, Goleta, CA
Lines: 22

jbuck@galileo.berkeley.edu (Joe Buck) writes:

%Example of CD salespeak: pushing oversampling as an advanced technical
%feature.  Oversampling is simply inserting zeros between the digital
%samples and thus increasing the sampling rate.  It's used because then you
%can use cheaper, less complex analog filters; it reduces the system cost.
%Still, some sales critters think it's an advanced technical extra.

Not all CD players just insert zeroes.  I used the same double oversampling
chip and the same DAC as my Denon 1500 CD player (well, I used the serial
versions) in my 56000 project board.  The oversampling chip did do
interpolation (and it was slightly more complex than bilinear (cubic spline?
I don't remember)).

I know the math works for inserting zeroes if you use a sinc function to
reconstruct the signal.  However, how does it work out for reconstruction
with a near step function?  I've never run through the math on that one...
Quickly off the top of my head, it doesn't look like it will work...

-- 
Todd Day  |  todd@appmag.com  |  appmag!todd@hub.ucsb.edu
		  ^^^^^^^^^^ coming soon!