METAL DETECTOR Russian patent published in 2003 - IPC

FIELD: detection of hidden objects containing metals. SUBSTANCE: invention can be employed to search for and identify objects hidden under surface in non-conducting or poorly conducting media. Metal detector has carrier frequency generator, induction converter, first amplifier, synchronous detector, first and second integrators and indicator. First amplifier is connected with output to input of synchronous detector and first integrator is connected with its input to output of synchronous detector. Metal detector also incorporates generator of main pulses, three frequency dividers, two delay circuits, AND gate, modulator, two differentiation networks, second amplifier, demodulator, third amplifier. Induction converter comprises two resonance circuits including emitting coil and receiving coil partially overlapping it and interlocking networks. Enable input of carrier frequency generator and enable inputs of first, second and third frequency dividers are connected to output of generator of main pulses, first frequency divider is connected with information input to output of carrier frequency generator and information inputs of second and third frequency dividers are connected correspondingly to direct and inverse outputs of first frequency divider, direct output of second frequency divider is connected to input of induction converter. First amplifier, synchronous detector and first integrator connected in series are coupled to output of induction converter. Modulator, first differentiation network, second amplifier, demodulator, second integrator, second differentiation network, third amplifier and indicator connected in series are linked to output of first integrator. First and second delay networks are connected with their inputs to output of generator of main pulses, AND gate is connected with one input to direct output of third frequency divider and with another input to output of second delay network. Output of AND gate is connected to reference input of synchronous detector, reference input of modulator is connected to output of generator of main pulses and reference input of demodulator is connected to output of first delay network. EFFECT: reduced energy consumption, increased detection range, potential for reliable differentiation of ferrous and non-ferrous metals. 2 dwg