Patent ID: 6504364
Filing Date: 2003-01-07
Classification: G01V

Abstract:
A method for carrying out measurements of a quantity by measuring an influence upon a magnetic field in a region of measurement in which a basic signal varying regularly with the time is generated and sent to a coil in the region of measurement for generating a magnetic field in accordance therewith, the magnetic field of the coil is detected in the region of measurement through generating a detection signal and a possible component deriving from an influence upon the magnetic field in the region of measurement associated with said quantity is separated from this detection signal for determining said quantity, wherein the polarity of the basic signal sent to the coil is changed regularly and synchronized with the length of time for a regular repetition of the basic signal, so that the coil is brought to generate a magnetic field on the basis of the basic signal so modified, an analysis of the detection signal induced in the region of measurement is controlled in synchronization with this change of polarity, and that a polarity change of the detection sign is carried out in synchronization with the polarity change of the basic signal before this analysis, in which polarity change means that the signal in question thereafter takes an opposite sign to the sign it would have had without such a change until a subsequent such change, after which it gets the same appearance as had none of the two last polarity changes taken place.