ODP: DCO's, Anti-Aliasing, and Filters

[Roman Sowa]

There are chips which do that.
And they use simplified method. I read about it a while ago but
cannot remember it now. The basic concept is like you described
but in reality it gets more simple

Those chips can resample in 2:1 to 1:2 sample frequency relations
and I saw some posts to this list about projects done with them.
and they are about 30$

Roman

> -----Oryginalna wiadomość-----
> Od:	Martin Czech [SMTP:martin.czech at intermetall.de]
> Wysłano:	4 grudnia 1998 08:45
> Do:	inman at interpath.com; cyborg0 at GlobalEyes.net
> DW:	synth-diy at mailhost.bpa.nl
> Temat:	Re: DCO's, Anti-Aliasing, and Filters
> 
> Eg.  the front end of a system runs with Fs 30 Hz, and the back end
> with 50 Hz sample rate (low figures, so I can calculate it in my head)
> or vice versa.  First you would go to an intermediate rate 300 Hz,
> the smallest integer multiple of both. Ie. every 10th (30 Hz) or 6th
> (50 Hz) sample has a real value, the others are zero. Then this would be
> lowpass filtered so that the Nyquist constraint is kept for the wanted
> output rate. This lowpass filtering will fill the zero samples with
> interpolation information.  Then you would keep only  every 10th or 6th
> sample and throw the others away. I think this is the only way for high
> quality sample rate conversion, ie. using an intermediate rate that is
> the smallest integer multiple of both rates.
> 
> What does this mean for the usuall 44100 to 48000 Hz conversion?
> Intermediate rate of 7,056,000 Hz !  Now I know why the high quality
> sample rate conversion algos need so long! There are faster algos that
> need less computation time, but they sound not that clean.
> 
> Or am I completely wrong? Is there a clean method that avoids these
> extreme high intermediate rates ?
> 
> m.c.
> 
> 
>