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NEXT (Near-End Crosstalk)
NEXT results show the crosstalk attenuation between cable
pairs. NEXT is the difference in amplitude (in dB) between a
transmitted signal and the crosstalk received on other cable
pairs at the same end of the cabling. Higher NEXT values
correspond to better cabling performance.
Because of insertion loss, crosstalk signals occurring farther
from the signal source are weaker and cause less trouble
than crosstalk nearer the source (Figure 3-15). For this
reason, NEXT is measured from both ends of the cabling.
Signal
source
Resulting
NEXT
For NEXT failures, the tester's diagnostic screens (
Info) may show more than one possible cause for the
failure. In this case, you can use the HDTDX analyzer results
to further diagnose the problem. See page 6-19 for details.
Figure 3-16 describes the NEXT plot.
Crosstalk near
the source
Figure 3-15. Near-End Crosstalk (NEXT)
Certifying Twisted Pair Cabling
Twisted Pair Autotest Results
Note
The 4 dB rule may apply to your NEXT results. See
page 3-13.
3
Fault
Crosstalk farther
from the source
AMD89F.EPS
3-23
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