A medical device locating system for determining disposition of a sensor coil in a subject, said system comprising an array of three or more triplet drive coil sets, each drive coil set including at least three discrete drive coils, each of the discrete drive coils being electromagnetic coils, at least one sensor coil adapted to provide one or more sensor coil response signals； a first system component that provides AC drive signals energizing said discrete drive coils； wherein the provision of drive signals includes one or both sequentially driving one or a pair or a triplet of said discrete drive coils within a triplet drive coil set and selectively providing phase inversion of the drive signal to any one, two or three of said discrete drive coils within a triplet drive coil set； a second system component for measuring resulting one or more sensor coil response signals, including one or more of sequential single, paired or triplet sensor coil response signals； an electrocardiogram (ECG) operably associated with said triplet drive coil array wherein one or more ECG reference leads are configured to be placed on said subject and a ECG signal lead is provided by a conductive core wire supporting said sensor coil and a computing component for calculating sensor coil disposition in the subject relative to said triplet drive coil sets.
