A metal sensor includes a primary coil, a compensation coil, a first additional coil, and a magnetic field sensor. The first additional coil is configured to be excited without the primary coil and the compensation coil being excited.

Buried object locators including an omnidirectional antenna array and a quad gradient array are disclosed. A locator display may include information associated with a buried object based on both omnidirectional antenna array signals and quad gradient antenna array signals.

A metal sensor includes a primary coil arranged in a first plane, a first compensation coil arranged in a second plane, a second compensation coil arranged in a third plane, and a magnetic field sensor arranged in a fourth plane. The first plane, the second plane, the third plane and the fourth plane are oriented parallel to one another and perpendicular to a common z-direction in each case.

A magnetic field sensing apparatus including a magnetic flux concentrator and a plurality of magnetoresistance units is provided. The magnetic flux concentrator has a top surface, a bottom surface opposite to the top surface, and a plurality of side surfaces connecting the top surface and the bottom surface. The magnetoresistance units are respectively disposed beside the side surfaces. The magnetoresistance units are electrically connected to form at least one kind of Wheatstone full bridge in three different periods, so as to measure magnetic field components in three different directions, respectively, and to cause the at least one kind of Wheatstone full bridge to output three signals corresponding to the magnetic field components in the three different directions, respectively.

A method of locating metal or non-metal containing objects and materials includes regulating currents in at least two emission coils in relation to each other. A reception coil output signal is received by at least one reception coil or average values of demodulation phases generated from the reception coil output signal are regulated in relation to each other continuously to be zero even when exposed to metal. The amplitude(s) of the required controlled variables are detected as a value by demodulation, preferably at least at 0 and at a demodulation which is set off by 90 and are equalized, thereby allowing a reliable detection of an object to be detected even if other metal objects are present in the area of detection.

This invention is related to the method providing computation of the signal frequency components in an acceptable accuracy in contravention of the shifts in the phase and the magnitude information caused by asynchronous sampling of the signals in the process of asynchronous sampling of metal detectors wherein the received signal by the receiver unit (4) divided into time intervals, say timing values those are far shorter than the sampling period and correspond to nearest probable sampling of the ADC (6); providing the computation of the sine and cosine coefficients or exponents of time constant coefficients of the said timing value from previously located or dynamically generated coefficient table; resulting the elimination of the requirement of synchronous sampling and the requirement of the signal period is multiple of the sampling period.

The present invention relates to a dual-technology detecting system, comprising: an archway, a metal detector housed in a first segment of the side panels, a millimetre-wave body scanner housed in a second segment of the side panels, said body scanner comprising at least one antenna configured to emit radiant energy, wherein, within the first segment, the internal faces of the side panels are separated by a distance at least equal to 800 mm and smaller than or equal to 900 mm, and within the second segment, a maximum distance between the internal faces of the side panels is larger than or equal to 1000 mm and smaller than or equal to 1200 mm.

A reception compensation apparatus based on airborne transient electromagnetic method is disclosed, and includes a receiver coil, a transmitter coil, at least one compensation coil, and at least one compensation magnetic core, where the transmitter coil is disposed around a periphery of the receiver coil. The at least one compensation magnetic core is disposed around an outer surface of the transmitter coil. The at least one compensation coil is disposed around an outer surface of the compensation magnetic core.

A detection device (100) includes a detection mat (102) having a plurality of detection coils (106), and at least one pair of groups of detection coils (106), the pair of groups of detection coils (106) includes first and second groups of detection coils (106). The first and second group of detection coils (106) comprises first and second first and second impedance values. The detection device (100) includes one or more drive sub-systems (112) and a comparison sub-system (112). The drive sub-systems (112) are operatively coupled to the detection mat (102) and configured to excite at least one pair of groups of detection coils (106). The comparison sub-system (114) is operatively coupled to the detection mat (102) and configured to receive a differential current signal from the pair of groups of detection coils (106), the comparison sub-system (114) is configured to generate a control signal based on the differential current signal.

This invention is related to the method providing computation of the signal frequency components in an acceptable accuracy in contravention of the shifts in the phase and the magnitude information caused by asynchronous sampling of the signals in the process of asynchronous sampling of metal detectors wherein the received signal by the receiver unit (4) divided into time intervals, say timing values those are far shorter than the sampling period and correspond to nearest probable sampling of the ADC (6); providing the computation of the sine and cosine coefficients or exponents of time constant coefficients of the said timing value from previously located or dynamically generated coefficient table; resulting the elimination of the requirement of synchronous sampling and the requirement of the signal period is multiple of the sampling period.