In either case, a substantial amount of energy will be re-
flected. If it were possible to have a cable with no loss, all
of the signal energy would be reflected. The incident and
the reflected signals would look identical.
Reflections from an impedance higher than the character-
istic impedance of the cable are in-phase, or upward. Re-
flections from an impedance lower than the characteristic
impedance of the cable are out-of-phase, or downward.
Inductive faults cause the TDR to display an impedance
higher than the characteristic impedance of the cable be-
ing tested. Capacitive faults cause the TDR to display an
impedance lower than the characteristic impedance of the
cable.
The Model 3300 displays the cable under test as a digi-
tized waveform and a numeric distance readout on the Liq-
uid Crystal Display.
The digitized waveform enables the operator to view the
signature of the cable in great detail. An impedance mis-
match (opens, shorts or faults of less severity) can be iden-
tified and the distance to the fault determined.