PERMEABILITY-MODULATED CARRIER REFERENCING

摘要

An apparatus and method for measuring the inductance of a wire-loop (20) without direct reference to any particular time-constant or frequency. Low- frequency noise induced into the wire-loop (20) is canceled within the detector circuit (24a, 24b) and crosstalk between a plurality of adjacent wi re- loops (20a, 20b) is nullified using passive transformers (22). New wire-loop configurations (20a, 20b) utilize the permeability-modulated carrier referencing to provide repeatable inductive signatures with less intrusive, and non-intrusive installations.