Re: gEDA-user: General ground/power plane design questions

[Steve Meier <smeier@alchemyresearch.com>]

True, the filter should match the spectrum of the frequency which 
contains the information of interest. The better the match the better 
the SNR. Also be carefull of where you set the gain so that you use a 
reasonable amount of the bits of the A/D. To high a gain and you will be 
clipping your signal... too low a gain and you won't make use of the 
resolution of the converter.

Steve Meier

Dan McMahill wrote:

> On Wed, Oct 20, 2004 at 09:07:48AM -0700, Steve Meier wrote:
>  
> > First, you should always have a low pass filter which is well bellow 1/2 
> > the sampling frequency just before your a/d converter.
> >    
> Make that "a band limiting filter whose bandwidth is less than
> 1/2 the sampling frequency".  There is no reason you need to choose this
> band to be the 0 to 0.5*Fs range.  A bandpass filter with passband
> from 1.1 to 1.4 times the sample rate is fine too.
>
> But of course, in this particular case, it is a low pass filter which 
> is called for.
>
> -Dan
>
>
>