If the value of the PVF or the cable type is not known then the PVF can be determined as follows.
7.4.2
DIELECTRIC CONSTANT (PERMITTIVITY) KNOWN
PVF
=
1
ε
Example: For polyethylene
ε
= 2.25
PVF
=
=
1
225
0 667
.
.
7.4.3
SHORT LENGTH OF SAME TYPE OF CABLE
1.
Measure physical length of the sample.
2.
Obtain a reading for the apparent length of the cable using any PVF value.
3.
Adjust the PVF value until the distance reading indicated is the same as the measured
length.
Radiodetection Ltd. 00901209-6
T631 OPERATING MANUAL
26