RE: Presentations for 802.3af
I was kind of intrigued by your observation about the "simple resistor detection scheme" below. I believe research is showing that due to variation in cables, board construction, manufacturing methods, time/temperature/tolerancing variations, etc. that the "simple resistor" is really a range of resistances that need to be detected. This results in the need for a relatively sophisticated discovery circuitry such as the microprocessor and A/D being used on the current prototype. Interesting issues around this then arise such as conducted noise from the microprocessor resulting in radiated noise on the cable, susceptibility to radiated noise picked up by the cable, what happens during ESD discharges, etc. Interestingly enough, Rick's tests show the resistor detection prototype to be noisier than the diode detection prototype for radiated noise. I'm really interested to see how many more counter-intuitive results are presented in Tampa. Sorry you can't be there to enjoy the sunny (we hope) weather.
Paul B. Moore
Hardware Engineering Manager
Small Business Solutions - Santa Clara
4401 Great America Parkway
PO Box 58185, MS SC05-02
Santa Clara, CA 95052-8185
At 08:56 AM 11/2/2000 -0800, DOVE,DANIEL J (HP-Roseville,ex1) wrote:
>I have some good news and some bad news. I will let the group
>decide which is which.
>Unfortunately, my current job responsibilities are going to keep
>me tied up so tightly that I can not make the Tampa meeting. I
>already reserved a room and thus might be able to transfer that
>reservation to someone else if they are in need. It would have to
>be a first-come-first-served basis though to prevent any appearance
>of favoritism. :)
>While I originally proposed the diode-detection method of discovery,
>I have come to appreciate the simplicity and low-impact aspects of
>Bob Leonowich's simple resistor detection scheme. I truly appreciate
>all of the effort put on by Rick Brooks and Robert Muir to develop a
>robust and cost effective diode-based detection method, but right now
>I lean to the resistive detection method.
>I hope that mid-span survives my absense as I know that there are others
>in the committee who find it the most cost-effective way for customers
>to apply power to their existing networks without involving a forklift.
>I hope I can make the next meeting. Have fun folks!
>PS: let the race for the room begin!
>_________ _/ ___________ Daniel Dove Principal Engineer __
>_______ _/ ________ dan_dove@xxxxxx LAN PHY Technology __
>_____ _/ ______ Hewlett-Packard Company __
>____ _/_/_/ _/_/_/ _____ Network Infrastructure Solutions __
>____ _/ _/ _/ _/ _____ 8000 Foothills Blvd. MS 5555 __
>_____ _/ _/ _/_/_/ ______ Roseville, CA 95747-5555 __
>______ _/ ________ Phone: 916 785 4187 __
>_______ _/ _________ Fax : 916 785 1815 __
>__________ _/ _________________________________________________________
> I n v e n t !