EXFO VDSL2 - Manual (Page 114)

Fault Location
106 AXS-200/635i
TDR Test
TDR Test
The TDR (time domain reflectometry) test allows you to easily locate
bridge taps (multiple appearances), the end of the cable, open ends,
shorted ends, splices, split pairs, and wet sections in a cable. It also allows
you to estimate cable lengths.
A TDR test transmits a fast pulse along the cable, then measures the
resulting reflected pulse as a function of time, and displays the results as a
function of the cable length or time.
Test Setup
The Test Setup tab allows you to
configure parameters for the TDR test.
VOP sets the velocity of propagation for
the cable as a ratio of the speed
of light.
Note: The default VOP is good for most
cables; only change it when you know
the correct VOP for the cable you are
measuring. An incorrect VOP will cause
distance errors.
TDR
The TDR test first attempts to find the
length of the circuit and then searches
all ranges from shortest to longest for
significant events. Upon completion,
the test selects the nearest major
event, sets the range to match, and
aligns the cursor with the event.
Est is the estimated length of the
circuit.