Information Technology Reference
In-Depth Information
FIGURE 15.5
A typical cable scanning report. (Courtesy of Datacom Technologies, Inc.)
The wire map tests are reported simply as Pass or Fail. The length measure-
ment is performed on all pairs of the cable under test, but the pair with the shortest
electrical delay is used for the Pass/Fail determination, and its electrical length (in
feet or meters) is reported. An additional 10% in length is permitted to allow for
uncertainty in the NVP of the cable.
The tester must make a determination of attenuation Pass/Fail based on a cal-
culation of the allowable attenuation at each frequency of measurement. If the cable
fails, the attenuation at the frequency (or highest frequency) of failure is reported.
Measurement steps are to be no greater than 1 MHz intervals up to 100 MHz for
Category 5e, or the maximum frequency for lower categories of cable. Attenuation
values of less than 3 dB are reported, but are not used in a Pass/Fail determination.
An optional determination of the attenuation per unit of length is calculated for
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