Object imaging using alternating magnetic fields - has two or more magnetic fields applied and primary signals induced in antenna compensated

摘要

At least two alternating magnetic fields of different frequencies are applied simultaneously. Primary signals induce in the receiving antenna by primary magnetic fields are compensated and applied from the transmitter through cables or auxiliary antennas to the receiver input. Phase selective demodulation is applied to correction to signals by corresp. reference signals whose phase is shifted by 90 deg. The frequency corresponds either in the case of the separate demodulation to a corresponding primary signal, or in the case of combination in pairs with the corresponding double side based auxiliary carrier, whose frequency is the arithmetical mean of corresp. frequency pair of primary signals.