Fwd: RE: detecting a PD disconnection event
All-
I may have picked on Jerry unfairly in my note attached below.
This note is intended to pick on everybody.
Please confine the discussions on this reflector to technical issues, NOT
to whether or not something will function as a patent work-around.
Avoidance of this area should be taken as seriously as avoidance of
discussions of cost.
Now that having been said, lets have a vigorous discussion of the
technical merits of a new approach.
We all know why a new approach is being discussed and nothing more needs
to be said about that.
Thank you.
Geoff Thompson, Chair, IEEE 802.3
Date: Mon, 30 Apr 2001 13:41:30 -0700
To: "Bachand, Jerry" <gbachand@xxxxxxxxx>
From: "Geoff Thompson"
<gthompso@xxxxxxxxxxxxxxxxxx>
Subject: RE: detecting a PD disconnection event
Cc: stds-802-3-pwrviamdi@xxxxxxxx
Jerry-
As I said to you in my private note.
Your discussion below is a legal one, not a technical one.
The judgement of the technical members of P802.3af, who are not expected
to be legal experts, are not particularly relevant to whether or not a
court would find that there had or had not been infringement.
You should have that discussion with your own legal staff, not
here.
If you choose to continue your support for a particular approach based on
your opinion that it would not infringe then go ahead.
If you choose to change your vote for a particular approach based on your
opinion that an earlier proposal would infringe then go ahead.
Either way, please do not use this forum discuss the matter of whether or
not an implementation would infringe. A discussion of that sort is a
legal matter, not a technical matter.
As I said in my original message, if you have questions or issues with
this them please take up with me directly and DO NOT copy the list.
Geoff
At 03:40 PM 4/30/01 -0400, Bachand, Jerry wrote:
Their application is for theft
prevention/security.
I didn't see in the patent, any mention of using the current drop
to
control/turn off power, I'm still looking though.
Since we are not involved in network security, as the patent title
states,
the patent shouldn't prevent any one from using a series loop current
drop
to detect the need to turn off power to a circuit.
Note: The title of the patent is:
Network Security System For Detecting Removal Of Electronic
Equipment.
If we stay out of the security business, we may be OK.
Jerry
Gerard E. (Jerry)
Bachand
Avaya Inc.
300 Baker Avenue, Suite 100
Concord, MA 01742
(978) 318-6402 Voice
(978) 318-6402 Fax
<gbachand@xxxxxxxxx>
Formerly: Enterprise Networks
Group
("Cajun" LAN Systems)
of Lucent Technologies
-----Original Message-----
From: Paul Moore
[mailto:pamoore@xxxxxxxxxxxxxxxxxx]
Sent: Monday, April 30, 2001 12:05 PM
To: Bachand, Jerry
Cc: Rick Brooks; Barry Male; stds-802-3-pwrviamdi@xxxxxxxx
Subject: RE: detecting a PD disconnection event
I believe the claims in the patent are very specific (that's probably why
it
was granted). It is for sensing loss of current on a
networking cable to
see if something has been disconnected. Unfortunately this is the
very
specific case we are working with, so it seem alternative solutions would
be
wise.
\Paul
At 12:06 PM 4/27/2001, Bachand, Jerry wrote:
Rick and group,
I still prefer 1a.
Since detecting a minimum current is such a basic and obvious means
to
detect a disconnect, I don't think anyone could even think of
suing. (Not
even Lucent or Avaya.) ;-)
This means of detecting a disconnect has been in use for over 100yrs
by
telephone companies, worldwide, to detect the telephone on-hook
condition.
However, I have no problem with other means, as you mentioned, as long
as
the minimum current method can still be used.
Please keep in mind, eventually there will be many other devices powered
by
the Ethernet, simple might give us more flexibility in the future.
Regards
Jerry
Gerard E. (Jerry)
Bachand
Avaya Inc.
300 Baker Avenue, Suite 100
Concord, MA 01742
(978) 318-6402 Voice
(978) 318-6402 Fax
<gbachand@xxxxxxxxx>
Formerly: Enterprise Networks
Group
("Cajun" LAN Systems)
of Lucent Technologies
-----Original Message-----
From: Rick Brooks [
mailto:ribrooks@xxxxxxxxxxxxxxxxxx
<mailto:ribrooks@xxxxxxxxxxxxxxxxxx>
]
Sent: Friday, April 27, 2001 1:40 PM
To: Barry Male
Cc: stds-802-3-pwrviamdi@xxxxxxxx
Subject: RE: detecting a PD disconnection event
Barry,
1a) was all of our favorites until Geoff's recent email regarding a
patent
issue.
It may turn out that other methods are more cost effective when
considered
globally.
My proposal is that more than one method could be used, not just the
one
that we have been assuming.
My view is that we must at least consider alternative methods that do
not
use DC current sensing.
thanks,
- Rick
-----Original
Message-----
From: Barry Male [SMTP:male@xxxxxxxxxxxxxxxxxxxxxx]
Sent: Friday, April 27, 2001 10:29 AM
To: Brooks, Rick [SC5:321:EXCH]
Cc: stds-802-3-pwrviamdi@xxxxxxxx
Subject: Re: detecting a PD
disconnection event
Rick,
My preference is 1a.
Have the PSE disconnect if the
AVERAGE value of load current is less
than
10mA for a sample period of some time (say 100mSec)
This averaging produces a
robust detection method from the
standpoint of
system noise.
Thanks
Barry
_________________________________________________________________
Barry Male
Senior Principal IC
Designer Internet:
barry_male@xxxxxx
Power Management
Products
NH Phone: 603.429.8705
Texas
Instruments
CT Phone: 860.844.8183
7 Continental
Blvd.
NH FAX : 603.424.3460
Merrimack, NH 03054-0399
USA CT FAX :
860.844.8806
On Fri, 27 Apr 2001, Rick
Brooks wrote:
> Just to start up another
discussion, I wanted to find out how many
people
> would support
> the following concept for detecting when a PD receiving power
becomes
> disconnected.
>
> the concept:
>
$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
>
> 1) The PSE is responsible for detecting when a PD receiving DTE
power
> becomes disconnected.
> If that event occurs, the PSE must turn off the power within some
time
frame
> (100ms to 500ms ballpark?)
>
> 2) The PSE may use any of the following methods to detect this
PD
disconnect
> event.
>
> a) the DC load current drop
below "X" ma (10ma?)
>
> b) the ethernet link has dropped
out
>
> c) another proven method
(pending discussion and feasibility proof)
>
some suggestions:
>
1) the AC probing circuit detects when the AC load changes
> (opens)
>
2) the PD modulation heartbeat current ceases
>
3) the PD response to a given PSE code is wrong or absent
>
4) other ideas
>
>
$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
>
>
> Please voice your opinions on this concept.
> The motivation here is to lower the cost of delivering DTE
power.
>
> thanks,
> - Rick
>
>
|=========================================|
| Geoffrey O.
Thompson
|
| Chair IEEE
802.3
|
| Nortel Networks, Inc. M/S
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