Self-calibrating magnetic field monitor

摘要

A self-calibrating magnetic field monitor is disclosed. In one embodiment, a magnetic field sensor repeatedly generates an electronic signal related to the magnetic field. In addition, a calibration module generates a relative baseline signal based on an average value of the electronic signals for a given time period. A comparator compares the electronic signal with the relative baseline signal and generating an output signal if a difference in the comparing is greater than or equal to a threshold.

主权项

1. A method for monitoring an area of interest with a plurality of magnetic field sensors, said method comprising:
providing a first magnetic field sensor on a first side of an area to be monitored; providing a second magnetic field sensor on a second side of the area to be monitored, a location of the first magnetic field sensor and the second magnetic field sensor resulting in an overlapping area to be monitored; receiving a first magnetic field strength signal intermittently from the first magnetic field sensor at a magnetic field monitor; receiving a second magnetic field strength signal intermittently for the second magnetic field sensor at said magnetic field monitor; comparing, at said magnetic field monitor, said first magnetic field strength and said second magnetic field strength for a given time period; determining, at said magnetic field monitor, whether a change in either of said first or said second magnetic field strength is correlated with a change in the other of said first or said second magnetic field strength, wherein a correlated change would signify an event occurring in an overlapping area; providing no output signal if it is determined that the event was not occurring in said overlapping area; and generating an output signal from the magnetic field monitor if the change in the magnetic field strength in the overlapping area is greater than or equal to a pre-defined threshold.