Fluke 990DSL, Руководство пользователя, Страница: 197 / 242

TDR Testing and Fault Location
The TDR Toolbox
6
6-15
Pair 2 to 1 Crosstalk Test
The Crosstalk test is useful for locating resistive crosses between pairs that are
typically caused by the breakdown of insulation due to water in a cable. This
test is also helpful for determining the location of a pair split and the location
of a split repair, when both split pairs are connected.
In this test the CopperPro applies launch pulses on Pair 2, but measures any
coupled reflections on Pair 1. The signal level of the resulting single trace is
directly proportional to the leakage between the two pairs, and the position of
the reflection occurs at the point of the leakage.
Note
The launch pulse does not appear on the Crosstalk test result screen
because it is launched on Pair 2. The result screen shows only the
signals occurring on Pair 1. However, any resulting influence on Pair
1 from the pulse, which may include slight coupling spikes from the
Launch Pulse leading and trailing edge, is displayed.
The TDR softkeys operate in the same manner as those on the Pair 1 test result
screen (see “Pair 1 Test” and Table 6-3 for descriptions).