Patent ID: 11899156

Abstract:
Provided is a method for detecting a metal target in soil using a metal detector including the steps of generating a transmit magnetic field for transmission into the soil using a transmit winding based on a transmit signal; receiving a first receive magnetic field using the transmit winding during a receive period to produce a first receive signal; and receiving a second receive magnetic field using a receive winding during the receive period to produce a second receive signal. The transmit winding and the receive winding are separated spatially; and producing an indicator output signal based on the first receive signal, the second receive signal and at least one synchronous demodulation function. The first receive signal includes first parameters that define a first transfer function transforming the first receive magnetic field into the first receive signal. The first parameters include 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. The second receive signal includes second parameters that define a second transfer function transforming the second receive magnetic field into the second receive signal. The second parameters include 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. 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 where the selection of the first parameters relative to the second parameters are dependent on the synchronous demodulation function.