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From: csdf@mit-vax.UUCP (Charles Forsythe)
Newsgroups: net.analog
Subject: Re: Oversampling in CD players
Message-ID: <334@mit-vax.UUCP>
Date: Fri, 2-May-86 04:19:33 EDT
Article-I.D.: mit-vax.334
Posted: Fri May  2 04:19:33 1986
Date-Received: Sun, 4-May-86 08:43:27 EDT
References: <241@ur-tut.UUCP> <285@mit-vax.UUCP> <175@brl-sem.ARPA>
Reply-To: csdf@mit-vax.UUCP (Charles Forsythe)
Organization: MIT, Cambridge, MA
Lines: 22

In article <175@brl-sem.ARPA> ron@brl-sem.ARPA (Ron Natalie <ron>) writes:
>> Every now and then, sombody comes up with some sort of interpolation
>> scheme. These invariably warp the spectrum and therefore don't work. The
>> point of oversampling is that you have "data to burn" so you can afford
>> to miss a few samples here and there.
>> 
>This is wrong.  The only reason for oversampling (which is really not
>really sampling many times but running the output D-to-A's at a higher
>rate than the original sampled material) is because good digital filtering
>is easier (read CHEAPER) than good analog filtering.

Ron is right, I was in error. I was told later about how oversampling
really works. The CD data is only sampled at ~40KHz.

The important point is that oversampling is not some sort of linear
interpolation but rather "upsampling". In upsampling, you insert 0's
between samples and you get the same information with a higher
bandwidth. This can then be filtered more easily ect.

-- 
From the land of Chaldea.
-Charles