[sdiy] Looking for cheap lowpass filter algorithm

[Martin Naef]

Hi Paul

paul.maddox.mail-list at synth.net wrote:
 >> So I'm looking for a cheap way in software to filter the high 
frequencies to make the distortion less noticeable.  Any pointers?

 > Lowpass filter on the input, *before* the ADC?

Essentially the same problem, except that you've moved it into the 
analog domain now where things such as phase linearity aren't really 
easier to design. The problem is that you need a *really steep* low-pass 
filter.

If you take a look at an audio ADC, you'll find that they oversample 
heavily to avoid/lessen the requirement for analog filtering, and then 
filter in the digital domain.

Bye
Martin

-- 
http://www.navisto.ch
http://www.myspace.com/navisto