Originally Posted by
Kimmo
So a larger signal would have a higher SNR. Where can I be wrong with this?
Well ... you are wrong in the sense that with indexed shifting the system has, so to speak, moved from analog to digital.
In the digital world the noise ratio isn't that important and we start speaking of "noise margin" instead of ratio because in the digital world any noise improvement above the noise margin does not contribute to a cleaner signal anymore.
As long as the losses in the system are lower than what is calculated to be a workable noise margin ... it'll be fine ... and it is fine ... for millions of people except you apparently.