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Sample testing for alien crosstalk - DTX Alien Crosstalk

It is not practical or necessary to test all of your links for Alien Crosstalk compliance.

The TIA does not specify a sampling plan. However, ISO/IEC 14763-2 (Draft) has defined a sampling plan for disturbed (victim) links of:

Installation size (No. of total links)

Sample size (No. of links to test)

3 – 33

100%

34 – 3,200

33

3,201 – 35,000

126

35,001 – 150,000

201

150,001 – 500,000

315

 

You are required to test an equal number of short, medium and long disturbed (victim links). ISO/IEC 61935-1 states that if three of the shortest, three of the medium and three of the longest links exceed 5 dB in margin, the user can opt to stop testing, 





DO NOT choose a disturbed (victim) link which is at the end of a row of connectors. This is not worst case.


Disturbed Links to Avoid in




DO select a long disturbed (victim) link that has at least one connector immediately adjacent to it in the patch panel.


Longest Link in Green





Once you have chosen your disturbed (victim) link, your disturbers should be cables in the same bundle. The disturbers are the cables you will energize. Alien Crosstalk across cable bundles is not considered significant.


Bundle Cable




Experience tells us that most of the Alien Crosstalk comes from the connectors. So it makes sense to have the connectors above and below as disturbers.

Additional Disturbers Links in Purple


Learn About:
- Troubleshooting LANs
- 10 Gigabit
- Fiber Testing

Author: Adrian Young

Creation Date: 2014-02-18

Last Modified: 2014-02-18