DSP-4000 Series
Users Manual
3-6
Link Performance Grade Result (Headroom)
When an Autotest is complete, the display shows the overall result (pass or fail)
and the headroom value. Headroom is the smallest difference found between the
NEXT measurements and their limits. This number serves as a figure of merit that
reflects the overall performance of the link. Larger headroom values correspond to
better cabling performance.
To pass or fail cabling based on a minimum headroom value, enter the minimum
value as part of a custom test standard (see Chapter 6).
On a DSP-4300 test tool, you can choose to see NEXT or the worst margin as the
headroom value by selecting HEADROOM in SETUP. The worst margin is the
measurement that came closest to failing or exceeded the limit by the greatest
amount.
Worst Margin and Worst Value Results
Worst margin and worst value results are shown for frequency-dependent tests
such as NEXT, RL, ELFEXT, and ACR. Worst margin results are measurements
that came closest to the limit, or that exceeded the limit by the greatest amount.
Worst value results are the lowest measurements found, which may not necessarily
come closest to the limit.
Worst margin results for attenuation are not required by any test standard and are
not reported.
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