Method and detector for detecting magnetic field amplitude disturbance body, position specifying method and position specifying system using this detection method
This method for detecting a disturber of magnetic field amplitude comprises: the emitting (62) of several magnetic fields of different frequencies from a same uniaxial magnetic field source, the amplitudes of the magnetic field emitted at two different unspecified frequencies being related to each other by a predetermined ratio, the measurement (64) of the amplitude of these magnetic fields at different frequencies by means of a same sensor, and the reporting (70) of an amplitude disturber if a ratio between two of said measured amplitudes diverges from a predetermined threshold of the predetermined ratio which relates the amplitudes of the magnetic fields emitted at the same frequencies and, if not, the absence of any reporting.
