48
SCAN-LAN VI
NOTE
The test result displayed on the graph is the worst value found within
1-MHz frequency increments for Category 5 and ISO Class D testing. All
test results are available and can be output from the SCAN-LAN VI.
6.2.6 C
ERTIFYING
C
ATEGORY
5 C
ABLING
—P
AIR
-
TO
-P
AIR
NEXT M
ETHOD
NEXT, as defined in TIA TSB-67, is a measure of signal coupling from one pair
to another pair within the four-pair cable. It is also sometimes called pair-to-pair
NEXT. TSB-67 requires that pair-to-pair NEXT be measured on all six pair
combinations, and that the worst pair-to-pair NEXT measurement not exceed
specified test limits for the Basic Link or Channel test configurations.
The pair-to-pair NEXT measurements, however, only account for crosstalk coupled
from any one pair to another—not the possible total crosstalk that might bc
coupled from multiple pairs in the same sheath. The TSB-67 methodology
assumes that only two pairs of the cable would be used at any given time for data
transmission. While pair-to-pair NEXT is an appropriate crosstalk measure for
2-pair network schemes, such as 10BASE-T and 100-BASE-TX, it does not provide
an adequate measure of cable performance when multiple pairs within the same
sheath may be transmitting simultaneously.
6.3 Length
The Length test measures the cable length and the distance to a cable fault,
such as a short, open, or impedance change.
The Length test locates significant impedance changes or anomalies
in a cable segment that may be caused by cable damage or inadequate
connections at patch panels, cross-connect blocks, modular plugs, or
wall plates.
Pair-to-Pair NEXT
measures signal
coupling from one
pair to another pair.
Summary of Contents for SCAN-LAN VI
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