3M
™
Advanced Systems Tester 900AST Series
47
Gain
0dB, 6dB, 12dB, 18dB, 24dB
Gain allows you to control the size of the trace
represented on the TDR. Higher gain will make
events look taller on the screen and is helpful for
finding small faults. The gain settings are referenced
to dB levels, so +6dB is twice as much gain.
Move Cursor
Always place the cursor to the left side of an event
to mark its location. Use the
and arrow
keys to move the cursor across the screen. The
distance from the 900AST tester to the cursor is
always shown in the center of the distance bar.
The 900AST tester TDR function automatically
compensates for the length of the special TDR
test leads. Zero distance is at the very end of
the test lead where it contacts the target circuit
under test.
The “Start” and “Stop” numbers shown in the
distance bar are the distances represented at the left
and right side of the screen.
If you move the cursor to the right side of the
screen, the screen will “pan” to the right. If you
move the cursor to the left side of the screen (and
the start distance is greater than 0 feet), the screen
will “pan” to the left.
If the cursor is moved to a position on the TDR
trace that is out of viewing range (above the top
of the screen or below the bottom), the trace is
shifted up or down to bring it into view. The x-
axis (horizontal) will not move. The vertical offset
will be maintained until the cursor is moved to
another point that is out of viewing range or until
one of the display controls is changed.
Event Recognition
Events are the “dips” and “peaks” seen on the
screen caused by faults or changes (such as an open
circuit or short) on the conductor or pair.
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