RE: A couple of questions on clause 52
Jonathan and others-
There are some that prefer OMA (pk-pk) and others that prefer OMA/2 (pk). I
strongly prefer OMA for the following reasons:
1. OMA has already been established and is well understood in Fibre channel
and HIPPI.
3. OMA represents the contrast between logic 0 and 1, which is directly what
matters.
2. OMA is simpler to explain, visualize, and implement (such as on a scope.
Finding toplines and baselines are easier than finding a waveform midpoint).
4. Some may think they can relate and therefore measure OMA/2 with average
power on a power meter. Because of the loose control on extinction ratio,
the two values can be quite different. We should not encourage any attempts
at such a relationship.
5. To your question - we must be consistent throughout the optical link.
That is, use the same definitions and units at the transmitter as we use at
the receiver, etc.
Tom Lindsay
Stratos
-----Original Message-----
From: Jonathan Thatcher
To: serialpmd
Sent: 4/16/2001 8:29 PM
Subject: A couple of questions on clause 52
Would someone please remind me:
1. Why is it that in the OMA tables that we spec the dBm range in OMA/2
instead of just OMA? We specify the Rx in OMA (dBm). Are we just testing
to see if the user knows to add 3dB when working on the link budgets? :-)
[rest deleted...]
jonathan