Breaking News
Comments
Newest First | Oldest First | Threaded View
satter
User Rank
Author
Re: All well and good, except...
satter   2/4/2014 7:04:21 PM
NO RATINGS
Sorry; however I think you are missing the point.  The varied twist of the pairs reduces the metallic coupling between pairs just as you have pointed out.  The coupling I am speaking of here is the longitudinal coupling between the pairs treated as single conductors.  In the article you can see that I have shorted the two conductors of each pair and teat each pair as a single wire.  These conductors do form transmission lines and store energy -- and can get you in trouble if not addressed.

Thanks for reading the article,

 

Jim

dougp01
User Rank
Author
All well and good, except...
dougp01   8/17/2013 6:40:55 PM
NO RATINGS
This all well and good except for one thing that seems to be ignored in the article. 

An assumption seems to be made that the coupling bewtween the conductors is a constant impedance over the entire legnth of the cable.  In fact, when Bell Labs first developed the concept of paired bundles for telcom wire many years ago, the problem of coupling between pairs was addressed.  The solution they adopted on pair-wises cables was to introduce a different twist rate on each pair of wires.  The effect they were seeking was to ensure that field coupling between pairs was cancelled every few centimeters.  With 8-pair cable this can be easily verified.  With 25-pair or 50-pair is it a little more difficult but this is where twist of pair-bundles comes into play.

 

-doug

 

 



Datasheets.com Parts Search

185 million searchable parts
(please enter a part number or hit search to begin)
Like Us on Facebook
Special Video Section
5G LTE is on the way. These systems will require more ...
Protecting sensitive electronic circuitry from voltage ...
09:45
Watch as a web server authenticates or rejects a water ...
Protecting sensitive electronic circuitry from voltage ...
Watch as a web server authenticates or rejects a water ...
Protecting sensitive electronic circuitry from voltage ...
Power can be a gating factor in success or failure of ...
Get to market faster and connect your next product to the ...
00:44
See how microQSFP is setting a new standard for tomorrow’s ...
The LTC3649 step-down regulator combines key features of a ...
Once the base layer of a design has been taped out, making ...
In this short video we show an LED light demo to ...
The LTC2380-24 is a versatile 24-bit SAR ADC that combines ...
In this short video we show an LED light demo to ...
02:46
Wireless Power enables applications where it is difficult ...
07:41
LEDs are being used in current luxury model automotive ...
With design sizes expected to increase by 5X through 2020, ...
01:48
Linear Technology’s LT8330 and LT8331, two Low Quiescent ...
The quality and reliability of Mill-Max's two-piece ...