Table 9.10 - Near-end cross-talk (NEXT) loss for catedories 3,4 & 5 data cables,

Table 9.10 - Near-end cross-talk (NEXT) loss for
------------------ catedories 3,4 & 5 data cables,
Cable category Channel cross-talk(dB) Basic link cross-talk
Cat. 3
19.3
21.0
Cat. 4
33.1
35.3
Cat. 5
40.6
42.3

Attenuation is the loss in the data cables and is measured in decibels (dB). The measurements taken for Table 9.10 are made at 16 MHz with a cable temperature of 20oC. The temperature coefficient of resistance indicates that copper cables increase in resistance as the temperature rises. The last column of the Table shows the percentage rise per oC above 20oC.

Table 9.11 - Attenuation values for some data cables at 20oC, measured at 16 MHz

Table 9.11 - Attenuation values for some data cables at 20oC,
------------------ measured at 16 MHz
Cable category Channel attenuation Basic link attenuation Attenuation increase
-
(dB/100m) (dB/100m) per °C (%)
Cat. 3
14.9
13.2
1.5
Cat. 4
9.9
8.8
0.4
Cat. 5
9.2
8.2
0.4

 

The percentage loss from input to output for a range of losses in decibels is given in Table 9.13

Table 9.13 - Decibel loss expressed as a ratio
Loss in dB V2 as a % of V1 Loss in dB V2 as a % of V1
0
100 %
4.0
63 %
0.1
98.8 %
20.0
10 %
0.2
97.7 %
40.0
1 %
0.5
94.4 %
60.0
0.1 %
1.0
89.3 %
80.0
0.01 %
2.0
79.4 %
100.0
0.001 %

Extracted from The Electricians Guide Fifth Edition
by John Whitfield

Published by EPA Press
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