dear all,

To analyze digital data Quality we use eye diagram, i agree but i want to know what are the impacts of different parameters like BW,GD. At the end of the day  a good sampler should sample with less BER. For example less BW will limit the signal swing in a given Tb, hence BER degradation which shows less horizontal opening on the eye diagram. Coming to group delay, assume i have receiver chain with enough BW but un- acceptable in band group delay ripple , so now signal will reach the level but the transition time between logic 1 and logic 0 depends on the bit pattern hence eye will be closed (i have no doubt on this), but if i have good CDR  which tracks slight dithering  then this won't be a problem. I would be glad if any expert can comment if any thing wrong in the above description.  

If there is no mistake in the above argument, then i would like partition between two causes which closes eye, one effect closes eye which is a real problem and another also closes eye, but with good CDR can be track-able.

Thanks,
Raj.