Thank you for those distinctions, Curtis, and for providing a launch pad
for a discussion in solitons.
Your characterizations of RZ and NRZ are accurate except for the polarity
you cited, I believe. Which was:
"In the electrical, Non-Return-to-Zero, NRZ simply means that
transitions from logical 1 (V+) to logical 0 (V-) cross zero voltage (and
vice-versa)."
According to popular conventions, as far as I'm aware, in both NRZ and
RZ, a (V-) equates to a logical one (1).
In NRZ, a (V+) equates to a logical zero (0). And in RZ, a zero voltage
level equates to a logical zero (0).
For your listening pleasure (make sure to let the shockwave load):
[Note: By "multiple current type" in the following, the narrator
simply means that both positive and negative going pulses are
used, as opposed to "single current type" where there is only
a -voltage and a zero state.]
dt-fad.mpt.go.jp
--------
"In the optical domain, there is no such thing as "negative light" or
photons.."
Yes, that's why I stated the two levels of light intensity, both the high and
low intensity levels. If need be, midway between high and low a zero
"reference" point may be established, which would equate to the zero
voltage state in the electrical domain. In other schemes, the high intensity
equates to an electrical (V-) or logical one (1), and the low intensity
equates to a (V+), or logical zero (0). Come to think of it, wouldn't it
really depend on the type of system, and what that system specification
was, since there are many? For example, both SONET and SDH use
NRZ and RZ in different situations.
"A logical 1, light on, in RZ, has light for about 1/3 of the bit period
with 2/3 light off; logical 0, light off, has the entire bit period with light
off."
I think that in at least some instances you will find that what you are calling
"light off" is actually a state of lowered light intensity. Of course, I could be
wrong. Come back...
Frank
ps - The pulse durations you mentioned are new to me in this specific
instance. Can these perhaps be responsible for the differentiation, on an
rms basis, for the high and low intensity levels I alluded to? What
standard are you citing here? I don't doubt what you're saying. Just
looking for your point of reference. |
