Device for reducing interference in the localisation of jacket defects

摘要

The device has a signal input unit in which an input signal including additive superposition of pulsed direct current (DC) voltage signal (101) and interference signals containing transient interference signal (411) and superimposed DC voltage is applied. A time constant of interference signal is made greater than transmitted signal period of pulsed DC voltage signal. A correction unit (421) is provided to automatically determine correction signal, and to apply the correction signal to input signal or to produce useful signal, so that useful signal is present at signal output unit. An independent claim is included for a sheath fault location device.