Branched conductor identification method e.g. for underground telecommunication cable or pipe - applying signals which generate two components, one for magnitude and one for end unit identification

摘要

The method involves applying signals to a branched cable network (10) including e.g. a transmitter (13) and end units (14,15,16). The point of application is at an end unit and the signal is detected at points within the network (A,B). The applied signal from the end units includes two groups of pulses. One group is the same for all units and they therefore add together. The other group, made up of two pulses, identifies the end unit. Variation from predicted values may identify conductors. Using a magnetometer a ground penetration probe containing locator antennae is driven towards the cable with information being provided as to its proximity.