EXFO CableSHARK P3 VF/DSL Cable Qualifier User Manual
Page 146
VF / DSL Cable Qualifier
134
Please check with the cable manufacturer for specific details concerning the cables
capacitance constant. The Capacitance Constant is used to calculate the length of
the cable based on the Capacitance measurement. The following table lists the
most common values.
Metric (mm)
AWG
nF/mile
nF/km
0.40 PE
80.5
50
0.405 26
PIC
83.0
51.6
0.50 PE
80.5
50
0.511 24
PIC
83.0
51.6
0.60 PE
64.4
40
0.644 22
PIC
83.0
51.6
0.90 PE
64.4
40
0.912 19
PIC
83.0
51.6
Table 8.7.1A – Capacitance Constants –
Metric & AWG Wire Gauges (0Hz/DC, 20
°
C or 70
°
F)
For measurements for T-G and R-G, the CableSHARK is set to 125 nF/mile or 77.7
nF/km.
Please note that cables containing any impairments including bridge taps
may severely affect the distance results based only on capacitance. It should
be noted that a TDR test will provide the most accurate determination of the
length of a cable.
CAPACITANCE
nF/mi or nF/km to
GND:
Allows the user to specify the cable’s capacitance to GND constant. The default
setting is 125 nF/mile or 77.7 nF/km.