Time Domain Reflectometry (Tdr) Technology - Fluke Networks TS100 Mode D'emploi

TS100 Cable Fault Finder
Users Guide
Table 3. VOP Values for Other Cables
VOP
78 Belden Drop Foam
82 CommScope Drop
87 CommScope Trunk
63 RG58/U 50 Ohm Network Coax
80 RG59 TV Coax
64 Service Wire
83 Times Fiber Drop
87 Times Fiber Trunk
93 Trilogy Trunk
68 Twisted Pair, Gel Filled 19 AWG
64 Twisted Pair, Gel Filled 22 AWG
62 Twisted Pair, Gel Filled 24 AWG
60 Twisted Pair, Gel Filled 26 AWG
68 Twisted Pair, Paper 22 AWG
66 Twisted Pair, Paper 24 AWG
65 Twisted Pair, Paper 26 AWG
72 Twisted Pair, PIC 19 AWG
67 Twisted Pair, PIC 22 AWG
66 Twisted Pair, PIC 24 AWG
64 Twisted Pair, PIC 26 AWG
10
Cable Type
Time Domain Reflectometry
(TDR) Technology
This section goes deeper into the theory of
operation. You can skip this section and still use
the tester effectively by reading the other parts
of this manual. However, it is worth reading this
section if you want more insight into how the
tester works.
One of the keys to understanding how the TS100
works is to first understand that a pair of wires has a
fixed impedance as long as the wires of the pair are
kept in the same geometrical relationship to each
other. A pair of wires (either standalone or within a
multi-wire cable) is designed to have a constant wire-
to-wire impedance. If the physical relationship of the
wires in the pair is altered during the wire run, then
there will be a change in impedance at the point
where the physical relationship changes. For example,
if one or both wires of the pair are broken (open), or
they are shorted to each other, or they become
sufficiently separated from each other, their impedance
will change. The TS100 looks for these changes in
impedance. If the impedance change is large enough,
(such as that caused by a break in one of the wires of
the pair), the TS100 will detect the impedance change
and will display the length of the wire up to the
impedance change.
From the previous information, it should be easy to
deduce that the TS100 can measure the length of a pair
of un-terminated wires, because, the open circuit at the
far end causes a very large impedance change.
The TS100 Cable Fault finder uses Time Domain
Reflectometry (TDR) to determine the length of the
target cable. A TDR, much like RADAR, sends a pulse
down the pair of wires. Part of that pulse reflects off
any impedance variations in the pair of wires. All of the
reflections, together with the original pulse, combine
to make an electrical signal (TDR waveform) that has
various flat and bumpy sections that represent the
Note