Breaking News
Comments
Newest First | Oldest First | Threaded View
RonCates
User Rank
Rookie
re: 10Gb/s Ethernet and 10GBase-T for the data center
RonCates   7/27/2011 11:37:27 PM
NO RATINGS
Sanjib – Yes, radiated emissions also need to be contemplated. But the good news is that the IEEE Standards body anticipated the potential for radiated emissions and has taken corrective measures. First, recognize that, like in 1000Base-T, 10GBase-T signaling is differential in nature and transmitted on twisted pairs that cancel emissions to first order. Nevertheless, there is residual radiation and even some common mode components due to non-idealities. To cope with those, IEEE was careful to architect the output energy of a 10GBase-T transmitter to be more evenly distributed over the transmission band and, furthermore, in Clause 55.9.5, requires compliant equipment to meet FCC Part 15 or CISPR 22 (depending on geography) limitations for radiated emissions. Bottom line: it’s purpose built to live and work in a data center environment without causing problems.

DF0
User Rank
Rookie
re: 10Gb/s Ethernet and 10GBase-T for the data center
DF0   7/27/2011 4:58:22 PM
NO RATINGS
I thought there was also an option for shielded cable for 10GBase-T.

Sanjib.A
User Rank
CEO
re: 10Gb/s Ethernet and 10GBase-T for the data center
Sanjib.A   7/26/2011 5:20:17 PM
NO RATINGS
Good point! I am not much concerned with only one cable. But I think, usually there would be many...isn't it? I thought it would be challenging to meet EMC norms as they would emit more when the cables are unshielded? But again I saw many have passed the EMC tests. One such example could be found below: http://docs.commscope.com/Public/Cat6AUTP_Passes_EMC_Tests.pdf

chanj0
User Rank
CEO
re: 10Gb/s Ethernet and 10GBase-T for the data center
chanj0   7/26/2011 3:18:58 PM
NO RATINGS
What is the current running through the cable that EMI becomes a concern?

Sanjib.A
User Rank
CEO
re: 10Gb/s Ethernet and 10GBase-T for the data center
Sanjib.A   7/26/2011 2:37:18 AM
NO RATINGS
Hi Ron, I got your points on crosstalk & EMC. Yes, that's how it could be done. Thanks a lot! Regarding the EMC (or rather EMI?) I was more concerned with the "unshielded cable" emitting RF energy creating trouble for others. Any thoughts?

RonCates
User Rank
Rookie
re: 10Gb/s Ethernet and 10GBase-T for the data center
RonCates   7/26/2011 1:26:38 AM
NO RATINGS
Sanjib – The Cat6A cables I have seen reduce alien crosstalk due to plastic ribs in their core which specially separate the twisted pairs. Since electromagnetic radiation intensity falls off as the square of the emission radius, it’s a very effective technique. As for Electromagnetic interference, I would agree with you if it wasn’t for the recent advances in the DSP algorithms inside of the 10GBase-T transceivers which have been shown to provide immunity to very strong EMI events of up to 10V/m. Those DSP engines are able to place a notch filter at the interferer’s emission frequency and prevent it from causing havoc with the received data.

Sanjib.A
User Rank
CEO
re: 10Gb/s Ethernet and 10GBase-T for the data center
Sanjib.A   7/25/2011 4:18:37 PM
NO RATINGS
As I know, the "alien crosstalk" was one of the biggest challenges for using the Cat6 cable for Gbit Ethernet. What is the change that is made in the insulation to reduce the alien crosstalk? In the second para in this article, it is mentioned about using "unshielded cable" for 10GbaseT. Again, I still see a major risk in using an unshielded cable for 10Gbit/sec due to EMC concerns.



Flash Poll
Top Comments of the Week
Like Us on Facebook
EE Times on Twitter
EE Times Twitter Feed

Datasheets.com Parts Search

185 million searchable parts
(please enter a part number or hit search to begin)
EE Life
Frankenstein's Fix, Teardowns, Sideshows, Design Contests, Reader Content & More
Max Maxfield

Vetinari Clock: Decisions, Decisions, Decisions …
Max Maxfield
33 comments
Things are bouncing merrily along with regard to my uber-cool Vetinari Clock project. The wooden cabinet is being handcrafted by my chum Bob (a master carpenter) using an amazing ...

Jolt Judges and Andrew Binstock

Jolt Awards: The Best Books
Jolt Judges and Andrew Binstock
1 Comment
As we do every year, Dr. Dobb's recognizes the best books of the last 12 months via the Jolt Awards -- our cycle of product awards given out every two months in each of six categories. No ...

Engineering Investigations

Air Conditioner Falls From Window, Still Works
Engineering Investigations
2 comments
It's autumn in New England. The leaves are turning to red, orange, and gold, my roses are in their second bloom, and it's time to remove the air conditioner from the window. On September ...

David Blaza

The Other Tesla
David Blaza
5 comments
I find myself going to Kickstarter and Indiegogo on a regular basis these days because they have become real innovation marketplaces. As far as I'm concerned, this is where a lot of cool ...