Patent ID: 7936168
Filing Date: 2011-05-03
Classification: G01D,G01R

Abstract:
1. Apparatus for indicating strength of a magnetic field, comprising: a first sensor for measuring instantaneous magnetic field strength, the first sensor having an output providing an indication of instantaneous strength of a magnetic field in which the first sensor is operatively located, and wherein the first sensor is oriented in a direction called a first sensor direction; a second sensor oriented in said first sensor direction and located adjacent to the first sensor and orientated so that it senses magnetic field in a same direction as the first sensor, the second sensor having an output providing an indication of rate of change of the strength of the magnetic field with respect to time; an integrator for integrating the output from the second sensor over time to derive relative changes of the strength of the magnetic field, the integrator having an output; and a processor connected to the outputs of at least the first sensor and the integrator; wherein the processor selectively provides an indication of the strength of the magnetic field from the output of the first sensor or the output of the integrator, depending on the strength of the magnetic field.