Let's take an example of an installation from Customer A:
Looking at the Disturber Ranking for the result above, we see:
It is clear that the majority of the alien crosstalk is coming from the immediate adjacent links. Experience tells us that the issue is with the patch panel and not the cable. Good news, since no one wants to even contemplate replacing installed cable. If it was the cable, you would see the contribution spread out more evenly. Let's take a look at an example where the cable is the issue.
Let's take an example of an installation from Customer B:
It PASSed, so everything is good. The installer can be paid and onto the next project. But wait, look at Pair 36! It just barely PASSed with a margin of 0.31 dB. All of my other results were at least 2.00 dB margin. What's different about this link. More importantly, why does this link have more PS ANEXT than my other links? Looking at the Disturber Ranking for this link, we see:
It is clear that the alien crosstalk is not coming from the immediate adjacent links. It is spread across the cables. Experience tells us that the issue is with the cable. So, who decided to create a bundle of 48 cables? May be if the bundle size was 24 cables, the performance would be better? Another nice aspect of measuring the links one at a time is that we can also delete them one at a time. Let's see what happens when we take away 24 of the disturbers:
The margin on Pair 36 changes from 0.31 dB to 5.32 dB. That is a very significant improvement.
If you need help troubleshooting alien crosstalk issues, please do not hesitate to send your *.alien file to firstname.lastname@example.org
- Fiber Testing