MOTM

>>You connect the analog and digital grounds through a 600ohm,
>>3A rated ferrite bead.
>
> A better way to put that would be "I connect the analog and digital
> grounds..."  While I'm curious why you do that.

Ferrite beads are a short at DC, but as the frequency increases, they become a 
high(er) impedance. A bead that is spec'd at '600ohms' means the complex 
impedance at 10Mhz is 600ohms.

Paul S.