Abstract: Provided is a method for detecting a target using a metal detector, including transmitting a transmit magnetic field using a transmitter; determining positions of a receiver of the metal detector as the receiver changes positions; receiving receive magnetic fields due to the transmit magnetic field to produce receive signals associated with positions using the receiver and receive electronics; and producing an audio output signal. The audio output signal is dependent on one or more receive signals associated with positions related to a current determined position in a selected relationship.

Abstract: A body for a handheld metal detector includes a lower end configured to engage with a sensor head; an upper end including an armrest connected to an upper shaft element; and a grip element intermediate to the lower end and the upper end, the grip element including a grip portion configured to allow a user to hold the body, and a first retaining means for slidably retaining the upper shaft element such that the distance between the armrest and the grip element is able to be adjusted.

Abstract: Provided is a body of a hand-held metal detector which includes an elongated body with a first and second end; and a first connecting structure moulded directly onto the elongated body at the first end through an injection moulding process. The connecting structure includes an engaging portion configured to engage at least one attachment of the hand-held metal detector, such that the at least one attachment is supported by the elongated body through the connecting structure moulded directly onto the elongated body.

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.

Abstract: An antenna of a handheld metal detector for detecting a target in a soil, the antenna including a housing including a bottom plane for facing the soil; two lateral sides; a front side; and a rear side; wherein the lateral sides, the front side and rear side are with respect to a user of the handheld metal detector holding and operating the handheld metal detector to detect the target in the soil; and at least one winding within the housing. A mean distance of conductors of the at least one winding near at least one of the two lateral sides of the housing is closer to the bottom plane than a mean distance of conductors of the at least one winding near at least one of the front side and rear side of the housing.

Abstract: A method for improving a performance of a metal detector, including: determining positions of a sensor head of the metal detector with respect to a coordinate system as the sensor head is moved on top of a ground; processing a receive signal received by the sensor head to produce a substantially ground balanced signal that is substantially insensitive to signals due to the ground; and actively controlling the step of processing based on one or more of the determined positions as the metal detector is moved on top of the ground; wherein, during a continuous use of the metal detector, the determined positions are processed to control, without any instruction or indication from an operator of the metal detector to do so, the step of processing the receive signal to produce the substantially ground balanced signal.

Abstract: A winding of an antenna of a metal detector, the winding includes multi-turn wire with both ends connected to the metal detector; and at least one resistive component for connecting a first part of the winding to a second part of the winding. The first part or the second part are not both ends of the winding. The resistive component is configured to damp an internal resonance of the winding with an order greater than 1.

Abstract: A metal detector for detecting a target, the metal detector including: a transmitter for transmitting a transmitted magnetic field; a receiver, including a winding with a plurality of turns, for receiving a magnetic field; and a receive electronics connected to the winding for receiving signals from the winding. The receiver further includes an electrostatic screen covering at least part of the winding. The electrostatic screen is connected to an electronic circuit to receive signals from the receiver to reduce an effective capacitance presented by the electrostatic screen to the winding.

Abstract: A method for detecting a target using a metal detector, including: transmitting a transmit magnetic field using a transmitter; receiving a receive magnetic field due to the transmit magnetic field to produce a receive signal using a receiver and receive electronics; processing the receive signal using at least one function to produce an indicator output, wherein the at least one function is controllable such that the properties of the indicator output is controllable in terms of: (a) an amount of cancellation of signals due to soil; wherein the amount of cancellation of signals due to soil is higher than an amount of cancellation of signals due to the target; and (b) a sensitivity of the indicator output to the target and broadband electromagnetic interference (EMI); wherein controlling the at least one function in a particular direction changes the at least one function from a first state more suitable for high ground response environments to a second state more suitable for medium ground response environmen

Abstract: A method for improving a metal detector, including: processing at least one receive signal due to a receive magnetic field using at least two functions to produce two processed signals, the at least two functions are selected such that the first processed signal is more sensitive to deeply buried targets than the second processed signal; and the second processed signal is more sensitive to shallow-buried conductive objects with characteristic frequency greater than 100 kHz than the first processed signal but not sensitive to saline soil, and that the two processed signals substantially complement each other in terms of sensitivity to targets in terms of target frequency and detection depth; and processing the two processed signals to produce at least one output signal which is sensitive to deeply buried low-frequency targets, shallow-buried low-frequency targets and shallow-buried high-frequency targets while signals due to saline soil are substantially rejected from the output signal.

Abstract: A metal detector, includes a transmitter for transmitting a repeating sequence of transmit magnetic field, each of the sequence includes a period of changing or constant non-zero transmit magnetic field, immediately followed by period of rapid change of transmit magnetic field, immediately followed by a period of substantially constant or zero transmit magnetic field; a receive coil; and a damping resistor. An end of the receive coil is connected to one end of the damping resistor and the other end of the damping resistor is connectable to a circuit with a variable parameter. A signal is induced in the receive coil during the period of rapid change of transmit magnetic field, and the signal induced in the receive coil decays at least at a termination of the period of rapid change of transmit magnetic field.

Abstract: A method for detecting an electrically conductive target in soil using a metal detector including the steps of: generating a transmit magnetic field for transmission into the soil based on the transmit signal; receiving a receive magnetic field; providing a receive signal induced by the receive magnetic field; determining a noise in the receive signal or a signal to noise ratio of the receive signal; and estimating, based on either the noise in the receive signal, or the signal to noise ratio of the received signal, or both, at least one effective detection depth of one or more types of electrically conductive targets in the soil.

Abstract: A method for detecting an electrically conductive target in soil using a metal detector, including the steps of: processing a receive signal using at least two different functions for producing at least two processed signals, each of the processed signals is at least partly insensitive to at least one unwanted signal due to the soil or an electromagnetic interference noise; determining a noise level of each of the at least two processed signals for producing at least two noise signals; and producing, from at least one of the at least two processed signals, an indicator output signal indicative of the presence of the electrically conductive target when the electrically conducting target is within the influence of a transmit magnetic field transmitted by the metal detector; wherein the step of producing an indicator output signal is dependent upon characteristics of the at least two noise signals.

Abstract: A metal detector transmitting, through a transmit coil, a repeating transmit signal cycle, which includes at least one receive period and at least one non zero transmit coil reactive voltage period; and sensing a current in the transmit coil during at least one receive period to control a magnitude and/or duration of the at least one non zero transmit coil reactive voltage period such that the average value of the current during at least one receive period of every repeating transmit signal cycle is substantially constant from cycle to cycle, and the current during at least one receive period is substantially independent of the inductance of the transmit coil.

Abstract: A method for reducing unwanted signals, due to a back emf decay, within a receive signal received by a receive coil of a metal detector during a demodulation of the receive signal after a transmission by a transmit coil of the metal detector, including controlling a T/R switch to control a characteristic of the back emf decay to reduce a duration of the period of the back emf decay.

Abstract: A method for detecting a change of an impedance of a magnetic field receiver of a metal detector, including: having a first network of passive components, including the impedance of the magnetic field receiver; having a second network of passive components, excluding the impedance of the magnetic field receiver; and processing a first measurement signal from a first node of the first network with a second measurement signal from a second node of the second network to detect the change in the impedance of the magnetic field receiver; wherein the first network, the second network, the first node, the second node is configured such that in an absence of an external influence which affects the impedance of the magnetic field receiver, the first measurement signal is substantially the same with the second measurement signal; and in a presence of the external influence, the first measurement signal is different from the second measurement signal.

Abstract: A method for reducing a delay, between a transition of a transmission of a metal detector and a process of a receive signal received by a receive coil of the metal detector, due to a critically damped time constant of the receive coil, including: introducing a negative capacitance into the receive coil to reduce the critically damped time constant.

Abstract: A method for detecting a target in a soil using a metal detector, including: generating a transmit magnetic field for transmission into the soil based on a transmit signal; receiving a receive magnetic field; providing a receive signal induced by the receive magnetic field; processing the receive signal for producing a set of data which has effects of signals from the soil reduced therein or removed therefrom; producing at least two components of a form of at least one time constant spectrum based on the set of data; and producing, at least one indicator output signal based on the at least two components for indicating the presence and/or identity of the target when the target is within, an influence of the transmit magnetic field.

Abstract: A method for detecting a target in a soil using a metal detector, including: generating a transmit magnetic field for transmission into the soil based on a transmit signal; receiving a receive magnetic field; providing a receive signal induced by the receive magnetic field; determining, based on the receive signal, a model of at least two independent components of the receive signal which are due to signals from the soil; processing the receive signal to produce a set of data which is with effects of the signals from the soil reduced therein or removed therefrom by fitting the model to the receive signal, then subtracting the fitted model from the receive signal; and producing, based on the set of data, an indicator output signal for indicating a presence and/or identity of the target.