[ee122] Clarification on a past midterm question

[vern at cs.berkeley.edu]

> My question is, are we still assuming we're referring to the same "high"
> and "low" used to encode 0's & 1's, say like the NRZ? Or is this
> information somehow encoded with the voltage on the line remaining above
> a threshold that would consider it "high"?

The former.  The point of this problem (which hopefully is apparent from
the solutions that I flagged earlier today) was to consider the problem
of "low" aliasing with "must be end of message, since there's no electrical
signal".  (It's a bit more than just NRZ's representation, since all of
the encoding schemes we've discussed have a notion of "low" vs. "high".
So for others, "low" might not be a 0-bit but instead encodes a bit - or
perhaps part of bit, for schemes like Manchester - which might be a 1-bit.)

		Vern