# Virtual Cable Tester (VCT)

## VCT Overview

The VCT technology enables end users to remotely diagnose the quality and characteristics of the attached cable. With this feature it is possible to detect and report potential cabling issues such as cable opens, cable shorts, and impedance mismatches. The distance of the fault can be reported within one meter.

## VCT Start

VCT can only be started if the corresponding adapter does not have a link up. If the link is up, DSP (Digital Signal Processor) is activated and reports the length of the cable.

To start VCT, proceed as follows:

1. Select a copper adapter in the select box.
2. Click START VCT.

The test is executed.

Depending on the result of the test, different states of the cable pairs, the distances (length) to the possible faults, and the test status are listed.

## VCT States

The following states of a cable pair are possible after VCT has been executed:

- Normal Cable:
  The cable pair is connected correctly.
- Short Cable:
  Two or more cable pairs are short-circuited together. VCT reports the distance to the short-circuit in meters.
- Open Cable:
  Lack of continuity between the pins at each end of the twisted pair cable, i.e. the cable pair is not connected correctly. VCT reports the distance to the open location in meters.
- Test failed:
  The test of the cable pairs was not successful.
- Impedance Mismatch:
  The impedance on the cable pair is not correct. Possible reasons for impedance mismatch:
  - The cable pair is not connected properly.
  - The cable pair is damaged.
  - The connector is faulty.

VCT reports the distance to the incorrect impedance in meters.

Copyright Marvell 2003