LXT9784

When looking at cabling plant installation, it consists of many different pieces:
   • The cable connection from the PC to the wall plate
   • The wall plate
   • The cables from the wall plate to the wiring closet
   • The wiring closet patch panels
   • The RJ45 connectors everywhere
   • The patch cables to the network hub.

Hand-held CAT-5 UTP cable testers are frequently used to isolate cabling problems. A typical cable test involves connecting one end of the cable to the tester, and connecting a remote node terminator or loopback module to the other end.

Then the tester performs cable link analysis and is able to detect the following conditions:
   • Short when two or more lines are short-circuited together.
   • Open Lack of continuity between pins at both ends of the cable.
   • Crossed pair When a pair is connected to different pins at each end (i.e. Pair 1 is connected to pins 1&2 at
      one end and pins 3&6 at the other).
   • Reversed pair when two lines in a pair are connected to opposite pins at each end of the cable (i.e. the line
     on pin 1 is connected to pin 2 at the other end, the line on pin 2 is connected to pin 1), also called  
     polarity  reversal.
   • Distance In addition it is able to locate the distance to an open or short and to measure cable length.

Cabling problems can be the cause of significant network downtime. With today's network manager more concerned about "Total Cost of Ownership", features that can help solve cabling problems provide valuable benefits. The Hardware Integrity (HWI) function incorporated into the LXT9784 is one such feature.

The Hardware Integrity function uses transmission line theory to measure the arrival time and LXT9784 electrical characteristics of the wave reflected back from an incident test wave launched on the media. With these measurements, opens, shorts, and degraded cable quality can be located along the wire, and lead the network manager to the location of the problem.

This document provides a theoretical overview of the HWI function implemented in the LXT9784.