🚀 go-pugleaf

>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.

I think the oversampling is not time interpolation (which by Nyquist
does not add any more information to the originial signal), but more 
error correction oversampling.  I.e. the same bit is sampled multiple
times to determine its value.  I assume that this is done by sampling
over the duration (space on the CD) of the bit.  Since the same bit
value is sampled multiple times (eight in the case of 8 times over
sampling) I assume some voting procedure is used to determine the
"true" (or best estimate) of the bit value.  I assume this results in
less tracking and sample errors.  For an ideal system, it also implies
that if the CD had a higher density (say 8 times) the laser can read 
it at this resolution (i.e. you could put 8 time the music on one
CD).

I think it is a little generous to think that the industry truely 
does "oversampling" as it is implied by signal processing connotations.
This (as you say) requires more compute requirements to ensure proper
interpolation of the sampled data.  If the interpolation (filtering)
is done wrong, then the quality of the output would go down...

- Jim Gaby

  gaby@rtc.reston.unisys.com