Patent ID: 7238539

Claim:
A method for operating a ferromagnetic thin-film based magnetic field detection system comprising a substrate, a plurality of magnetic field sensors capable of sensing externally applied magnetic fields up to a saturation magnitude value that are supported on said substrate of which at least one can have magnetically permeable particles provided sufficiently close thereto to be capable of sensing resulting variations in said externally applied magnetic fields and of which at least one is substantially unaffected by such magnetically permeable particles, and an output circuit electrically connected to said plurality of magnetic field sensors to provide an indication of changes therefrom due to sensings of externally applied magnetic fields thereby, said method comprising: applying an external magnetic field primarily along a first direction to said plurality of magnetic field sensors of a magnitude substantially equaling or exceeding said saturation value; applying an external magnetic field primarily along said first direction to said plurality of magnetic field sensors of a magnitude less than said saturation value; and measuring changes in said indications provided by said output circuit resulting in said applyings of said external magnetic fields.