EXFO CableSHARK P3 VF/DSL Cable Qualifier - Manual (Page 90)

VF / DSL Cable Qualifier
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F IGURE 8.2.1A – M ANUAL TDR T EST S ETUP M ENU
The TDR Test Setup menu has several options that appear at the upper part of the screen (see the previous
illustration). The parameters can be modified to customize a TDR Test. The following describes the TDR
test setup options:
TEST TYPE: This option can be set to AUTO – CABLE END, AUTO – BRIDGE TAP, MANUAL, or
MANUAL – 4 WIRE. AUTO – CABLE END is an automatic search for any valid
reflection(s) denoting the end of the cable. AUTO – BRIDGE TAP is designed to
automatically search for bridge taps connected to the cable. The user need only set
Cable Type, VOP, and Horizontal Units.
The MANUAL setting is a more detailed analysis of the cable plant. Users can modify
any setting to “customize” the test. The MANUAL setting is also used to look for any
reflections beyond the capability of the AUTO TDR test. The MANUAL – 4 WIRE test
type uses the 2 Wire TX / RX and the RX (Aux.) connectors on the rear panel of the
CableSHARK (see section 4.1.2A). The 4 WIRE TDR sends a pulse of energy down
one pair of wires and looks for any reflections on the RX pair of wires.
CONNECTION: Connection is for TIP-RING.
CABLE TYPE: The CABLE TYPE setting is used to select the appropriate cable type or more
appropriately the appropriate diameter. It is best however to ensure the correct VOP
for the cable as all cables are manufactured differently. The available options for
Imperial Measurement Units are 19, 22, 24, and 26 AWG. For METRIC Measurement
Units, the options are 0.4 mm PE, 0.5 mm PE, 0.6 mm PE, and 0.8 mm PE. Note:
AWG = American Wire Gauge.
The AUTO selection is based on an optimized algorithm whereby the user does not
need to know the cable gauge. It takes into account Resistance per unit length,
Capacitance per unit length and Attenuation per unit length, in addition to POTS
splitters.
VOP: Velocity of Propagation sets at what velocity the pulse travels along the wire. It is
entered as a ratio of the speed of light. The two tables near the end of this section
provide more information about VOP. A correct VOP will ensure accuracy in the test
results. An incorrect VOP can mean a result that indicates the loop is too long or too
short.
VOP (m/ μs): Rather than specify the ratio of the speed of light for pulses traveling along a length of
wire, users can specify the speed in meters per microsecond. Changes made to VOP
(m/
μs) will automatically be reflected in the VOP setting and vice versa. (Range is
from 120 to 299 m/ μs)