3 Copper tests
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ARGUS Copper Test Manual
3.1.4.1 Calculating line length
Every telecommunication cable has a certain loop resistance and operating capacitance
per unit of length. As the type of cable laid is generally known, this value too is known. The
values are design-related and relatively constant, as the cables are laid in the earth and
subject to relatively minor temperature and humidity effects. However, a typical subscriber
line can consist of multiple segments. In these segments, the wire cross-sections, and thus
the technical specifications, can vary. These parameters can also be stored in the device. If
the C or R measurement is now carried out, an evaluation of the measured line is obtained
with regard to its probable length in relation to the selected cable type.
This can only be determined for a measurement between the Tip- and Ring-wires. The
measurements with respect to Ground can be subject to random influences and thus
cannot be specified with a general capacitance or resistance value per unit of length. The
line length calculations can then be compared with the line length, which is generally also
known, thus providing information about faults. Using the calculated value, you can roughly
compare the line lengths and conduct further fault-finding (e.g. with a TDR) in the event of
discrepancies.
A wire type must be selected to enable calculation of the line length using a C or R measu-
rement. The wire type can be selected and configured during or after the measurement.
You can obtain further information on the settings in the ARGUSpedia on the
instrument.
