Method and apparatus for determining the magnitude of a field in the presence of an interfering field in an EAS system

摘要

A method and apparatus for determining the amplitude of a first magnetic field at a first fundamental frequency in a zone in which a second magnetic field is able to be present wherein first and second transmissions of a magnetic field at the fundamental frequency and different phases is carried out at different times, the field in the zone is detected for each transmission and the detected fields are processed to determine the magnitude of the first magnetic field.