Hi Jeff,
The main reason why we need to specify what is the power level that P2PRUNB need to be addressed is because it is obvious question. We don’t need P2PRUNB spec in two pair systems and equally justified arguments
for 4P system when current in the pair is less than TBD so there is no 4P system interaction and effect on 4P system performance below this point just like in 2P.
Please see the mathematical analysis and you will see why. It based on physical facts.
Please see my comments below.
Thanks
Yair
From: Jeff Heath [mailto:jheath@xxxxxxxxxx]
Sent: Wednesday, April 30, 2014 7:19 PM
To: STDS-802-3-4PPOE@xxxxxxxxxxxxxxxxx
Subject: Re: [802.3_4PPOE] From which total PD load current , the XXX_P2PRUNB requirements is not required to be met. - Update
Hi Yair,
Regarding ‘the list of facts’ on page 1
I don’t recall a straw poll or a motion showing wide consensus that we have two types of 4P systems of the type you call out. Can you point me to such a poll or motion if I have
missed it? If not it would be good to establish this in the meeting in Norfolk in the entire Task Force as it seems a bit outside of the scope of this ad-hoc to decide this.
Yair: There is no straw poll or motion etc. This is not important to the technical discussion. The objective of this statement is to separate the analysis to two parts:
a)
60W systems (I call it Type 3, call it whatever you want)
b)
>60W systems and less than 100m. (I call it Type 4).
The analysis focus on Type 3 systems were my analysis is relevant.
That’s why the separation it doesn’t require consensus or motion. It is physical fact for focusing the analysis on the concern (systems of 60W and >60W).
I appreciate if you suggest different language to reflect the intent explained here.
---------------------------
I am aware that there are a considerable amount of components such as magnetics that are designed for 600mA operating in 2 pair systems but aren’t most of these I would guess
are cost optimized for operating 600mA in 2 pairs, not 2 X 600mA in 4 pairs. The main issue here would be heating which is a factor of 2 higher.
Yair: There are many vendors and many components for Type two magnetics and other components in general, that was designed for 4P operating as well since 802.3at time with the same vision that we have when we specify
the cable temperature rise when all 4P are conducting with 600mA while 4P operating was not defined in 802.3at. We were prepared for it since then and we want to continue to use them.
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In any case, having available components for any power level is a good thing however, this is an implementation issue and the OEM is free to use any and all components available
for their power level and operating temperature range.
Yair: Correct, but why is relevant to the technical analysis that helps simplifying the spec and narrow the discussion for the need for P2P Unbalance spec to the places it is needed?
The components issue was an example why such analysis is a good thing.
The main reason why we need to specify what is the power level that P2PRUNB need to be addressed is because it is obvious question. We don’t need P2PRUNB spec in two pair systems and equally justified
arguments for 4P system when current in the pair is less than TBD so there is no 4P system interaction and effect on 4P system performance below this point just like in 2P.
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I am again not aware of an objective or motion for this Task Force that states we are going to make a specification based on available ‘at’ components (other than the channel
e.g. cable, connectors) that may or may not be available today.
Yair: See above my response. Per my understanding how IEEE works, we don’t need motions to do the work, being prepare to obvious questions that will be address at next meeting and have some progress.
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Regards,
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Jeff Heath |
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402 East Carrillo Street, Suite D |
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From: Darshan, Yair [mailto:YDarshan@xxxxxxxxxxxxx]
Sent: Wednesday, April 30, 2014 3:05 AM
To: STDS-802-3-4PPOE@xxxxxxxxxxxxxxxxx
Subject: [802.3_4PPOE] From which total PD load current , the XXX_P2PRUNB requirements is not required to be met. - Update
Hi all,
Please see updated version of the above.
I did some work to explain some issues raised during our last ad-hoc regarding the question of what is the total PD power that below it we don’t have to meet xxxP2PRUNB requirements.
Please review and let me know if it is clear and it make sense to you.
I would like to discuss the issue on Thursday.
Thanks
Yair
Darshan Yair
Chair
Power over HDBaseT Subcommittee
HDBaseT Alliance
Chief R&D Engineer
Analog Mixed Signal Group
Microsemi Corporation
1 Hanagar St., P.O. Box 7220
Neve Ne'eman Industrial Zone
Hod Hasharon 45421, Israel
Tel: +972-9-775-5100,
Cell: +972-54-4893019
Fax: +972-9-775-5111
E-mail: <mailto:ydarshan@xxxxxxxxxxxxx>.