Thread Links Date Links
Thread Prev Thread Next Thread Index Date Prev Date Next Date Index

[802.3_SPEP2P] Questions regarding Insertion Loss and Return Loss proposals

Dieter/Peter/Matthias –

Thank you for your presentation the other day.  I was in the process of looking at the effects of these on PHY parameters for a follow up, and noticed a few odd things in the proposal that needed some clarification.  I am sending this to the reflector in case others had the same questions.


All references are to slides in , since I haven’t gotten around to posting your update.

First, the return loss – the proposed values on slide 4 (Return Loss for a link) drop below zero at the low end of  the frequency range (9 + 10log(f) = -1 dB at 0.1 MHz).  Is this intended?


Second, the insertion loss has an odd form.  Each limit has a factor in front of it (5.05 for the 500m link, 3.05 for the 300m link, and 1.05 for the 100m link).  I can understand the desire to scale by length, hence the 5, 3, or 1, but what is the 0.05 for?  If it is for a percent margin, then shouldn’t that be an  additional factor of 1.0x, where x is the % margin?  Why is it a constant, .05 for all the lengths?


Third, it seems odd, and possibly incorrect to consider the 100m motor control link to have exactly the same form as the building automation link.  The cabling described by Dayin Xu for these application has a substantially different construction than two wire cabling used in building automation constructions.


Finally, the cabling you propose for process control seems substantially lossier than what Steffen had described.  I presume you are assuming 18 AWG rather than the 16 AWG Steffen based his estimates on.  Is that correct?


George Zimmerman, Ph.D.

President & Principal

CME Consulting, Inc.

Experts in Advanced PHYsical Communications




To unsubscribe from the STDS-802-3-SPEP2P list, click the following link: