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Re: [802.3_RTPGE] Link segment insertion loss and cable gauge

 
Sterling,
 
The calculations are self consistent. 23 AWG solid is the reference not 24 AWG solid. The loss increases are given as 12% increase per gauge (solid) (e.g., 23 AWG solid to 24 AWG solid) and 20% increase from solid to stranded (e.g., 23 AWG solid to 23 AWG stranded). From the chart, going from 23 AWG solid (0.45 dB) to 23 AWG stranded is 1.2*0.45 dB=0.54 dB. See slide 5 in http://www.ieee802.org/3/bp/public/mar13/diminico_3bp_01_0313.pdf
 
I believe the scaling is consistent with slide 4 and slide 5 in the presentation submitted by CommScope...
 
At this point we need a channel basis for insertion loss that addresses gauge and temperature that's simple and scales rationally. I'm not trying to align with all of the requirements of structured cabling standards.
 
Regards, Chris
 
 
In a message dated 4/5/2013 2:41:11 P.M. Eastern Daylight Time, sterlingv@xxxxxxxxxxxxx writes:
Using 0.45 dB/m as the reference, going to 24 AWG stranded is usually scaled by a factor of 1.2, which yields 0.54 dB/m whereas your presentation shows 0.61 dB/m

Similarly the transition from 23 AWG solid to 26 AWG stranded the scaling factor is usually 1.5 which yields 0.675, which also does not match the 0.77 predicted in the presentation.

These calculations would be accurate if 24 AWG solid is used as the reference.

These cable types are typically jacketed when used in structured cabling, which does of course affect the insertion loss factors. We have found in our internal testing of sample cables, a very close match to the 1.2 and 1.5 factors (scaled from 23 AWG) for insertion loss de-rating for structured cabling cables. That is probably due to the cable manufacturers designing to the limits of the standard. If the twisted pairs are not jacketed, then the insertion loss curve will differ from the reference IL.

Sterling Vaden

On 4/5/2013 12:29 PM, Christopher DiMinico wrote:
Todd,
 
Todd wrote: I would suggest that we provide Insertion Loss equation based on Cat6A / Class Ea with scaling factor for gauge size and temperature de-rating co-efficient.
 
Chris: The basis for the March presentation was to provide such information.
 
Regards,
 
Chris
 
 
In a message dated 4/5/2013 12:18:54 P.M. Eastern Daylight Time, THerman@xxxxxxxxxxxxx writes:

In my opinion, we need to find the optimal solution for the overall system without over constraining the PHY development with extreme Insertion Loss.  Unlike previous IEEE projects in the Enterprise space, there is no “installed base” for this automotive application.  All RTPGE installations will require new harnesses and “green field” applications.  I would suggest that we provide Insertion Loss equation based on Cat6A / Class Ea with scaling factor for gauge size and temperature de-rating co-efficient.  By doing this, PHY designer can optimize their proposal with any combination of gauge size and temperature range to meet the end customer’s requirements.

 

Regards,

Todd Herman
Sr. Engineering Manager
CommScope
1300 East Lookout Drive, Suite 150
Richardson, Texas 75082  USA
phone: 1-972-792-3128
cell: 1-469-236-4948
therman@xxxxxxxxxxxxx

http://www.commscope.com/

www.commscope.com | www.commscopeblogs.com

 

From: Christopher DiMinico [mailto:CDimi80749@xxxxxxx]
Sent: Monday, April 01, 2013 8:30 AM
To: STDS-802-3-RTPGE@xxxxxxxxxxxxxxxxx
Subject: [802.3_RTPGE] Link segment insertion loss and cable gauge

 

Colleagues,

 

Coming out of the March meeting (see link below to minutes), we have identified 26 AWG stranded as a "target" cable gauge to consider based on RTPGE survey responses (see link below). Please note, I expect, consistent with other copper IEEE 802.3 link segments, other cable gauge sizes (e.g., 24 AWG, 28 AWG, 30 AWG) may be used to build compliant RTPGE link segments (i.e., link segments have been specified without a requirement for cable gauge). The maximum link segment insertion losses for the 15 meter topology listed in the RTPGE objectives is characterized using 26 AWG stranded in order to address the survey response requests.

 

Regards, Chris DiMinico

MC Communications

Channel definitions Ad hoc co-chair

 

 

meeting minutes (unconfirmed)

http://www.ieee802.org/3/bp/public/mar13/minutes_3bp_u_0313.pdf

 

The survey is targeted at automotive OEMs and suppliers to be used
to assist the IEEE 802.3 Reduced Twisted Pair Study Group
(RTPSG) in developing link segment objectives and project criteria.

 

Reduced Twisted Pair Gigabit Ethernet Link Segment Characteristics

 

Reduced Twisted Pair Gigabit Ethernet PHY Study Group Objectives
APPROVED 802.3 WG (November 15, 2012)

 

 

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