🚀 go-pugleaf

From: chased@rbbb.Eng.Sun.COM (David Chase)
 
>kong@leland.Stanford.EDU (Kong Kritayakirana) writes:
>
>>Nope. They insert 1, 3, or 7 zeros between samples (corresponds to 2, 4, 
>>and 8 times oversampling respectively) and then pass the zero-inserted 
>>signal through a digital low pass filter that interpolates nicely 
>>between the points.
>
>So what you are saying is that they do interpolate, and that they
>implement this interpolation with a digital low-pass filter?  That
>is, I didn't provide you with an easily contradictable paragraph, so
>"nope" is a little confusing.  Can you provide an example of what one
>of the filters would look like?  For example,
 
Yes. They DO interpolate this with a digital low pass filter. It is usually 
done with a type of filter called FIR (Finite Impulse Response) The output is 
the function of the present and past input only.
 
>   out(i) = out(i-1) + in(i)/2 + in(i+1)/2 - in(i-1)/2 - in(i-2)/2
 
This is an example of an IIR (Infinite Impulse Response) filter. The problem 
with IIR is that it's hard to guarantee linearity of phase and sometimes they 
oscillate in the LSBs. This oscillation is refered to as "limit cycles."
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Kong Kritayakirana  (kong@leland.stanford.edu)
Remotely reading and posting to rec.audio from
a nice beach somewhere in south pacific.  Damn
the technology that helps  us to get in touch.
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