Patent ID: 11899156
Assignee: MINELAB ELECTRONICS PTY. LIMITED
Field: Measurement (Instruments)
Classification: CPC G | IPC G

Claim 0:
1. A method for detecting a metal target in soil using a metal detector, said method comprising steps of:
generating, by the metal detector, a transmit magnetic field for transmission into the soil using a transmit winding based on a transmit signal;
receiving, by the metal detector, a first receive magnetic field using the transmit winding during a receive period to produce a first receive signal;
receiving, by the metal detector, a second receive magnetic field using a receive winding during the receive period to produce a second receive signal, wherein the transmit winding and the receive winding are separated spatially; and
producing, by the metal detector, an indicator output signal based on the first receive signal, the second receive signal and at least one synchronous demodulation function;
wherein the first receive signal comprises first parameters that define a first transfer function transforming the first receive magnetic field into the first receive signal, the first parameters comprising an effective number of turns, a geometry of the transmit winding, and first electronic amplification transfer functions between the transmit winding and first receive signal;
wherein the second receive signal comprises second parameters that define a second transfer function transforming the second receive magnetic field into the second receive signal, the second parameters comprising an effective number of turns, a geometry and a relative orientation of the receive winding with respect to the transmit winding, and second electronic amplification transfer functions between the receive winding and second receive signal;
wherein the first parameters and the second parameters are selected such that the first receive signal and the second receive signal are processed together to reduce or null detected signals within the indicator output signal due to received soil eddy currents from conducting soil components manifested in the first receive signal and the second receive signal; and
wherein the selection of the first parameters relative to the second parameters are dependent on the synchronous demodulation function.