Abstract: A metal detector has one or more feedback loops to control its repeating transmit signal cycle so that there is no reactive voltage drop across the transmit coil of the metal detector during at least one receive period of the metal detector.

Abstract: A method for detecting electrically conductive targets in soil including the steps of: 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; selecting at least two models, each approximating a form of a signal due to a different type of source; processing the receive signal using the at least two models to produce at least two independent signals, each representing a component of the receive signal due to a different type of source; and producing, based on at least two independent signals, an indicator output signal indicative of the presence of the electrically conductive target.

Abstract: A method for detecting an electrically conductive 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 to produce a processed signal; processing a duration of the receive signal, the duration begins after a time the processed signal exceeds a threshold value and ends after a time the processed signal no longer exceeds the threshold value, to produce more than one estimations indicative of a presence of the electrically conductive target when the target is within an influence of the transmit magnetic field; and presenting graphically the more than one estimations.

Abstract: This invention relates to a support arrangement for an implement such as a metal detector, the support arrangement comprising a harness worn by a user, the harness comprising an attachment point for a first load-bearing element transferring a load associated with the implement to the attachment point, and a second load-bearing element transferring the load from the attachment point to a further point on the harness.

Abstract: A method for detecting an electrically conductive 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 to produce a processed signal; processing a duration of the receive signal, the duration begins after a time the processed signal exceeds a threshold value and ends after a time the processed signal no longer exceeds the threshold value, to produce more than one estimations indicative of a presence of the electrically conductive target when the target is within an influence of the transmit magnetic field; and presenting graphically the more than one estimations.

Abstract: A metal detector for detecting a metallic target in a soil including: transmit electronics for generating a repeating transmit signal cycle, the repeating transmit signal cycle including at least one receive period and at least one non-zero transmit coil reactive voltage period; a transmit coil connected to the transmit electronics for receiving the repeating transmit signal cycle and generating a transmit magnetic field; a receive coil for receiving a receive magnetic field during the at least one receive period and providing a receive signal induced by the receive magnetic field; and receive electronics connected to the receive coil for processing the receive signal during the at least one receive period to produce an indicator output signal, the indicator output signal including a signal indicative of a presence of the metallic target when under an influence of the transmit magnetic field; wherein the repeating transmit signal cycle is generated such that a waveform of the repeating transmit signal cycle i

Abstract: A method for detecting electrically conductive targets in soil including the steps of: 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; selecting at least two models, each approximating a form of a signal due to a different type of source; processing the receive signal using the at least two models to produce at least two independent signals, each representing a component of the receive signal due to a different type of source; and producing, based on at least two independent signals, an indicator output signal indicative of the presence of the electrically conductive target.

Abstract: A method for improving a sensitivity of a metal detector by reducing an unwanted magnetic field generated by at least one electrically conductive element of the metal detector, the metal detector transmitting a transmit magnetic field into a soil and a possible target within the soil which in response generate a response magnetic field, the method including the step of: redirecting at least a portion of the response magnetic field from entering the at least one electrically conductive element, wherein otherwise the at least one electrically conductive element within an influence of the response magnetic field generates the unwanted magnetic field due to a change in an intensity of the response magnetic field entering the at least one electrically conductive element, the redirecting adapted to reduce or eliminate the unwanted magnetic field generated by the at least one electrically conductive element thereby improving the sensitivity of the metal detector.

Abstract: A highly flexible real-time metal detector platform which has a detection capability for different targets and applications, where the operator is able to alter synchronous demodulation multiplication functions to select different types or mixtures of different types to be applied to different synchronous demodulators, and also different waveforms of the said synchronous demodulation multiplication functions; examples of the different types being time-domain, square-wave, sine-wave or receive signal weighted synchronous demodulation multiplication functions. The operator can alter the fundamental frequency of the repeating switched rectangular-wave voltage sequence, and an operator may alter the waveform of the repeating switched rectangular-wave voltage sequence and corresponding synchronous demodulation multiplication functions.

Abstract: The present invention relates to a method for detecting an electrically conducting target in soil, including the steps of generating a repeating transmit signal cycle of a fundamental period using transmit electronics, the repeating transmit signal cycle including a first period and a second period within each fundamental period; generating a transmit magnetic field using a magnetic field transmitter, based on the repeating transmit signal cycle, for transmission into the soil; receiving a receive magnetic field using a magnetic field receiver; producing a receive signal induced by the receive magnetic field; arranging for a current flowing through the magnetic field transmitter to flow to a first potential through a damping resistor during the second period for providing a damping effect on the current flowing through the magnetic field transmitter; arranging for the current flowing through the magnetic field transmitter to flow to a second potential, predominantly through an alternative path with a lower re

Abstract: A metal detector includes means for reducing the induction of eddy currents in conductive elements of a sensor head. The aim of this invention is to remove the effect of small pieces of conductive material, located within or close to the sensor head, being seen as sought targets as the sensor head is moved over magnetic matrix. The means is to surround the conductive material with material with high magnetic permeability and low losses in a time-varying magnetic field, say low-loss ferrite. This will prevent the reflected field from illuminating the conductive material so eddy currents are not generated.

Abstract: This invention discloses a low cost metal detector which suppresses signals arising from signals induced in a receive inductor from a rate of change of environmental static fields. The metal detector processes a signal due to a rate of change of environmental static fields to produce a first signal, and processes a signal due to the transmitted magnetic field to produce a second signal, the second signal includes a proportion of the first signal. Signal processing includes the subtraction of an estimation of the proportion of the first signal from the second signal to produce a third signal, such that the third signal is substantially independent of the first signal; and the receive electronics further processes the third signal to produce an indicator output signal, the indicator output signal includes a signal indicative of the presence of a metallic target and is substantially unaffected by the signal due to a rate of change of environmental static fields.

Abstract: A metal detector including transmit electronics having a plurality of switches for generating a repeating transmit signal cycle for transmission by a transmit coil. The repeating transmit signal cycle includes at least a high voltage period, and at least a low voltage period, the low voltage period followed by a substantially zero voltage period. The output impedance of the transmit electronics is less than three times the equivalent series resistance of the transmit coil during the low voltage period and the substantially zero voltage period.

Abstract: A metal detector including transmit electronics having a plurality of switches for generating a repeating transmit signal cycle for transmission by a transmit coil. The repeating transmit signal cycle includes at least a high voltage period, and at least a low voltage period, the low voltage period followed by a substantially zero voltage period. The output impedance of the transmit electronics is less than three times the equivalent series resistance of the transmit coil during the low voltage period and the substantially zero voltage period.

Abstract: This invention relates to metal detectors used to detect metal targets in soils wherein the detector is insensitive to signals induced by a received magnetic field due to perpendicular components of a uniform conducting half-space, including metal detectors simultaneously capable of suppressing signals due to components of substantially log-uniform viscous superparamagnetic soil, and including metal detectors using repeating transmit signal cycles resembling a pulse induction-like waveforms. It discloses signal processing, in particular synchronous demodulation functions which may simultaneously substantially suppress signals due to perpendicular components of a uniform conducting half-space in a received magnetic field, signals due to components of substantially log-uniform viscous superparamagnetic soil, and signals due to a movement of the receive coil with respect to a static magnetic field.

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, and the current during at least one receive period is substantially independent of the inductance of the transmit coil.

Abstract: A highly flexible real-time metal detector platform which has a detection capability for different targets and applications, where the operator is able to alter synchronous demodulation multiplication functions to select different types or mixtures of different types to be applied to different synchronous demodulators, and also different waveforms of the said synchronous demodulation multiplication functions; examples of the different types being time-domain, square-wave, sine-wave or receive signal weighted synchronous demodulation multiplication functions. The operator can alter the fundamental frequency of the repeating switched rectangular-wave voltage sequence, and an operator may alter the waveform of the repeating switched rectangular-wave voltage sequence and corresponding synchronous demodulation multiplication functions.

Abstract: A method for generating a transmit signal for transmission including the steps of a) generating at least two selected rectangular wave signals, each having a different fundamental frequency; b) mixing the selected rectangular wave signals to produce a driving signal; and c) driving a switching circuit using the driving signal for generating a transmit signal for transmission, wherein the Fourier transform of the transmit signal contains frequency components of relatively high magnitude, at frequencies corresponding to the convolution of the fundamental frequencies of the said at least two selected rectangular wave signals, as compared to other frequency components across the frequency spectrum of the Fourier transform, and wherein the rectangular wave signals are selected such that the frequency components of relatively high magnitude are substantially the same in magnitude, and spaced from each other in the frequency spectrum in a predetermined manner.