Abstract: An apparatus for locating a magnet and/or determining the orientation of the apparatus relative to the magnet. In one embodiment, the apparatus includes a multi-axis magnetic field sensor movable in a reciprocating manner so as to permit sensor readings at multiple spaced locations. In another embodiment, the apparatus includes a plurality of multi-axis magnetic field sensors arrayed along a straight line. The apparatus may be used in a number of medical and other applications, including tissue resection, tracking movement of a medical device in a body cavity and tracking movement of an internal organ.

Abstract: A measured magnetocardiography signal has a relatively small heart signal mixed with a large noise signal. To produce a heart signal having a reduced noise content, the times of occurrence of a time-series of isoelectric intervals of the measured signal is first determined and a time-series isoelectric artifact curve is formed from the measurements made at those times of occurrence. A time-series non-isoelectric artifact curve for other times is determined from this information. The time-series isoelectric and nonisoelectric artifact curve is subtracted from the measured magnetocardiography time-series signal to yield a time-series heart amplitude signal having reduced noise and undistorted form.