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DSP-100/2000
Users Manual
3-12
NEXT Test
The NEXT test measures the crosstalk between cable pairs. This crosstalk value is
expressed as the difference in amplitude (in dB) between the test signal and the
crosstalk signal. NEXT is measured from the main-unit end of the cable over a
frequency range defined by the selected test standard.
If the NEXT test fails, you can use the TDX analyzer to locate the source of the
crosstalk on the cable.
The first NEXT screen displays the cable pairs tested, the worst-case NEXT
margin, and the test result for each set of pairs.
To see detailed results for the cable pairs, use D U to highlight the pairs; then
press @ View Result. Table 3-4 describes the items on the NEXT results
screen.
Table 3-4. Items on the NEXT Results Screen
Item Description
Pairs
The cable pairs relevant to the results.
Result
The overall result for the NEXT test. A PASS result indicates that the NEXT
between the cable pairs was higher than the specified NEXT for the selected test
standard. A FAIL result indicates that the NEXT was lower than specifications.
NEXT
The worst-case NEXT. Worst-case NEXT is the measured NEXT value that is
closest to falling below specifications. If the NEXT falls below specifications, the
value displayed is the value that falls the farthest below specifications.
Frequency
The frequency where the worst-case NEXT value is measured.
Limit
The lowest NEXT value acceptable for the worst-case frequency.
Margin
The difference between the worst-case NEXT value and the limit. A positive number
means that the measured NEXT value is higher than the limit (PASS). A negative
number means that the NEXT is lower than the limit (FAIL).