10
Wire Mapper Pro Model CA7028
• Under
Type
, the following selections can be made:
TIA568 STP
TIA568 UTP
ISDN
USOC UTP
USOC STP
NOTE:
For testing of wiremap in accordance with ISO11801 & EN50137
the product should be set to TIA568 which is the equivalent standard.
For FTP and SSTP cables use the STP setting.
• Vp is selectable in the range 20% to 100%.
(see § 4.3 if the Vp is not known)
• The Wire Mapper Pro may be set to measure cable length in feet or meters.
• The instrument may be set to operate in English (USA or UK), French,
German, Italian, Spanish or Portuguese.
• The display contrast may be set by selecting
Contrast
and then press-
ing the
SERVICE / Vp
button to
decrease
the contrast or the
LENGTH / Vp
button to
increase
the contrast and optimize the display to the ambient
lighting conditions. The unit also has a display backlight.
• To exit set up mode, press the
button.
4.3 Determining and Measuring Vp Values
Vp, or Velocity of Propagation, values are characteristic of each cable
type and brand. The Vp is used to measure the length of a cable and to
measure a fault location. The more accurate the Vp, the more accurate the
measurement result will be.
The cable manufacturer may list the Vp on their specification sheet or
may be able to provide it when asked. Sometimes this value is not readily
available, or the user may wish to determine it specifically to compensate
for cable batch variations, or for special cable applications. This is quite
easy:
1. Take a cable sample of exact length increments (ft or m) longer than
60ft (20m).
2. Measure the exact length of the cable using a tape measure.
3. Connect one end of the cable to the Wire Mapper Pro (see § 4.11).
Leave the end un-terminated and make sure the wires do not short to
each other.
4. Measure the length and adjust the Vp until the exact length is displayed.
5. When the exact length is displayed, Vp is established.
