Fluke 990DSL, Руководство пользователя

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990DSL
Users Guide
6-12
After determining the best set of parameters for the specific type of reflections
that it detects, the CopperPro displays a
continuous image of the waveform on
the screen. If you want to see the effect of a different pulse width or filter, you
can
do so at any time, with the continuous test automatically displaying the
resulting waveform.
Note
The reflection cursor is automatically positioned as close as possible
to the leading edge of the largest reflection. However, it is
recommended that you manually expand the horizontal (Zoom) and
vertical (Gain) scales in order to zero in on the reflection. Then move
the reflection cursor until it is at the leading edge of the reflection
and until it just begins to move off the horizontal baseline. The
Δ
C
value should now be the most accurate possible distance to the fault.
After a waveform is displayed, you can force the unit to increase or decrease
its pulse width by pressing
A
(
Range
) and then
G
or
I
. To go back to the
AUTO
pulse width, press
I
until
AUTO
is displayed. This procedure may be
used on all continuous TDR tests.
Pair 1 and 2 Compare Test
The Pair 1 and 2 Compare test enables you to see continuous TDR waveforms
from Pair 1 (T and R) and Pair 2 (T1 and R1) simultaneously. This test is
typically used to compare a good pair (Pair 1) with a suspected faulty pair
(Pair 2) in the same count so that you can see the differences between the two
more closely.
Figure 6-3 shows a typical Pair 1 and 2 Compare test result screen. 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).