Gradiometric Directional Metal Detector
First Claim
Patent Images
1. A metal detector comprising:
- a first resonant circuit comprising a first coil, wherein the first resonant circuit is configured to transmit a first circuit transmit signal;
a second resonant circuit comprising a second coil, wherein the second resonant circuit is configured to receive a second circuit receive signal;
a third resonant circuit comprising a third coil, wherein the third resonant circuit is configured to receive a third circuit receive signal; and
a controller comprising logic to determine a gradient, variable in at least one dimension, based on the second circuit receive signal and the third circuit receive signal.
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Accused Products
Abstract
An implementation of a direction finding and magnetic nulling metal detector is provided. Some embodiments of the present invention provide for a metal detector having multiple resonant circuits and associated coils for transmitting a primary transmit signal, transmitting a magnetic nulling signal, and receiving a receive signal. A controller includes logic to process the generate the transmit signals and to process the received signal in order to determine a gradient vector along one or two dimensions, a depth and whether or not a metal object is ferrous.
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Citations
26 Claims
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1. A metal detector comprising:
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a first resonant circuit comprising a first coil, wherein the first resonant circuit is configured to transmit a first circuit transmit signal; a second resonant circuit comprising a second coil, wherein the second resonant circuit is configured to receive a second circuit receive signal; a third resonant circuit comprising a third coil, wherein the third resonant circuit is configured to receive a third circuit receive signal; and a controller comprising logic to determine a gradient, variable in at least one dimension, based on the second circuit receive signal and the third circuit receive signal. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A metal detector comprising:
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a first resonant circuit comprising a first coil and a transmit amplifier having an output coupled to the first coil, wherein the first resonant circuit is configured to transmit a first circuit transmit signal; a second resonant circuit comprising a second coil and a receive amplifier having an input couple to the second coil, wherein the second resonant circuit is configured to receive a second circuit receive signal; a third resonant circuit comprising a third coil and a secondary transmit amplifier having an output coupled to the third coil, wherein the third circuit is configured to transmit a third circuit nulling signal; and a controller comprising logic to determine the third circuit nulling signal based on the second circuit receive signal. - View Dependent Claims (9, 10)
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11. A method of determining a gradient relative to a metal detector and metal hidden behind a surface, the method comprising:
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transmitting, from a first resonant circuit, a first circuit transmit signal; receiving, from a second resonant circuit, a second circuit receive signal; receiving, from a third resonant circuit, a third circuit receive signal; and determining a gradient based on the second circuit receive signal and the third circuit receive signal. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 24)
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23. A method of determining a gradient relative to a metal detector and metal hidden behind a surface, the method comprising:
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generating a primary transmit signal, generating a magnetic nulling signal and measuring a sequence of receive signals from a first receiver channel; averaging the sequence of receive signals from the first receiver channel to form a first average value; generating a primary transmit signal, generating a magnetic nulling signal and measuring a sequence of receive signals from a second receiver channel; averaging the sequence of receive signals from the second receiver channel to form a second average value; normalizing the first and second average values; and computing an offset from a centerline in a first dimension based on a component of the first and second average values in the direction of the first dimension.
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25. A method of magnetically nulling, the method comprising:
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transmitting a primary transmit signal from a first coil; receiving a first receive signal from a second coil for first receiver channel; amplifying the received signal; determining parameters for a first magnetic nulling signal based on the first receive signal; and transmitting the first magnetic nulling signal from a third coil while receiving a second receive signal from the second coil for the first receiver channel. - View Dependent Claims (26)
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Specification