Table of Contents

A simple explanation of test parameters for twisted pair cabling

Outline

Traveling signals is like electrons following a somewhat rocky path

But every cable has at least 4 electronic highways

There are potholes in the road….

There are also bumps and dips in the road: return loss

On top of that: the road is not level and electrons fly off!

Near End Crosstalk (NEXT)

Far end crosstalk (FEXT)

Some electrons may fly into the air and eventually land on earth!

Alien Crosstalk

Combine two effects: attenuation and NEXT: S/N = ACR

Combine two effects: attenuation and FEXT: S/N = ELFEXT

Return Loss S/N when signals travel in both directions on same wire pair

What about ACR and ELFEXT?

What is “power sum” NEXT and “power sum” ELFEXT?

The concept of “power sum”

Compare power sum with worst case “voltage sum”

Voltage sum is often too pessimistic

Now you all know what the various parameters mean …...

Computed values are: …...

Each application has assumptions for ...

What do applications need? (1)

What do applications need? (2)

Conclusions

Koeman Henriecus is the Fluke delegate to the Telecommunications Industry Association (TIA) and also participates in the ISO and IEC work at the international level. He is an active contributor, particularly to test and measurement aspects of US and international standards.

Within Fluke he is responsible to certify the performance of Cable meters to applicable standards.

Comments are always appreciated:

Henriecus ("Henri" or "Riekus") Koeman

Fluke Corporation

P.O. Box 9090 6920 Seaway Boulevard

Everett, WA 98206 Everett, WA 98203

Tel: 425-356-5399 Fax: 425-356-5043

E-mail: koeman@tc.fluke.com