7.9
RETURN LOSS (dBRL) MEASUREMENTS
The T631 has two principles of operation.
1.
Simple fault location.
2.
Qualitative measurement and location.
In the Simple Fault Location mode the pulse width is automatically selected with each range to
one best suited to provide a strong reflection from the fault, in order to easily identify and locate
it. No significant conclusion can be drawn from the amplitude of the reflected pulse although its
polarity is indicative of the type of fault.
i.e. Upwards – positive – high series impedance
Downwards – negative – low shunt impedance
In order to gain a measure of the significance of the reflection it is necessary to compare the
amplitude of the reflected pulse with that of the transmitted pulse.
The amplitude of the reflection resulting from an impedance change, relative to that of the
transmitted pulse is a measure of the impedance mismatch at that point and the ratio is referred
to as the reflection coefficient.
Radiodetection Ltd. 00901209-6
T631 OPERATING MANUAL
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