Re: [10GMMF] TP3 call Meeting Minutes Dec 14
Mike reported:
> Tom presented thinking that at present we have to test for
> overload conditions both in the informative sensitivity test
> and the stressed Rx sensitivity test.
The draft says "The receiver under test shall satisfy the comprehensive stressed receiver ... overload". Note "shall satisfy" not "must be tested". We didn't hear any reason why not satisfying these conditions would be acceptable.
Either these are readily satisfied, in which case the burden is light, or they aren't, in which case an explicit requirement is the more necessary. At present, the committee doesn't know which. Mike suggested keeping just the "simple" overload requirement: the disadvantage with this is that the "simple" requirement is informative, and we need a normative overload requirement.
If the draft is neither incomplete nor incorrect in this area, I suggest we spend our time, for now, on the other areas where improvement IS needed. Later, when we have some reports of overload testing in practice, we can refine it.
One small wrinkle does occur to me: bad-frequency-response channels are (nearly?) always ones with connector offsets. Connector offset with power near the outside of the core is associated with loss. Modal noise is strongly correlated with connector loss. So, we are not likely to experience maximum power, bad frequency response AND high modal noise together. But reducing the noise loading for the overload criterion may not make much difference in practice.
Piers
> 5. Informative Rx Sensitivity Testing
>
> Tom raised a point that we need to check that we are
> describing the end condition and not defining implementation
> choices in the test. This would lead to us defining a nominal
> rise time (around 129ps) rather than specifying a BT filter
> with a given bandwidth. Piers felt that it was ok as it was
> currently written. Piers and Tom agreed to look over it again
Tom's right, my apologies. For the normative receiver test, we even have a NOTE saying that other implementations are OK. The informative one needs rewording - whether we want to describe the TP3 signal by risetime, bandwidth or both.
Piers
> -----Original Message-----
> From: owner-stds-802-3-10gmmf@ieee.org
> [mailto:owner-stds-802-3-10gmmf@ieee.org]On Behalf Of Michael Lawton
> Sent: 16 December 2004 11:16
> To: STDS-802-3-10GMMF@listserv.ieee.org
> Subject: [10GMMF] TP3 call Meeting Minutes Dec 14
>
...
> 4. Overload proposal
>
> Tom presented thinking that at present we have to test for
> overload conditions both in the informative sensitivity test
> and the stressed Rx sensitivity test. There was some
> discussion around whether this could be reduced to a test
> that would be acceptable. Piers and Tom had views on this and
> agreed to keep working on this.
>
> 5. Informative Rx Sensitivity Testing
>
> Tom raised a point that we need to check that we are
> describing the end condition and not defining implementation
> choices in the test. This would lead to us defining a nominal
> rise time (around 129ps) rather than specifying a BT filter
> with a given bandwidth. Piers felt that it was ok as it was
> currently written. Piers and Tom agreed to look over it again
>