Patent ID: 7705606

Claim:
A method of determining the state of a cable at least one electrical conductor, in which method a test signal is generated and applied to at least one conductor of the cable by a non-contact electrical coupling transmitter, propagating the resulting signal along the at least one conductor and using a non-contact electrical coupling receiver to pick up a reflected signal, and comparing the reflected signal to expected state signal values for the cable to determine its current state, wherein at least one expected state signal value is stored in memory means, wherein the at least one expected state signal value is the signature for the ‘empty’ state of the line under test, wherein the expected state signals include port connected and operating, outlet device connected and working, cable damaged, cable disconnected from port and device connected to outlet but not powered up, and wherein the signatures, other than for the ‘empty’ state, are derived signal values rather than measured reference values.