| Patent application number | Description | Published |
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| 20090315707 | REAL-TIME RECTANGULAR-WAVE TRANSMITTING METAL DETECTOR PLATFORM WITH USER SELECTABLE TRANSMISSION AND RECEPTION PROPERTIES - 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. | 12-24-2009 |
| 20100019769 | METAL DETECTOR HAVING CONSTANT REACTIVE TRANSMIT VOLTAGE APPLIED TO A TRANSMIT COIL - An electronic metal detector having, a transmit coil arranged and adapted to transmit an alternating magnetic field associated with a reactive transmit coil voltage, the transmit coil being connected to transmit electronics arranged and adapted to generate a transmit signal, the transmit electronics having at least two power sources, a first power source and a second power source, wherein the first power source is adapted and arranged to connect to the transmit coil for at least a first period, and the second power source is adapted and arranged to connect to tie transmit coil for at least a second period, the said transmit electronics including at least one servo control negative feedback loop, a first servo control negative feedback loop, which is adapted and arranged to monitor a transmit coil current for at least part of the said first period, and to control at least part of the said transmit signal, the transmit electronics being adapted and arranged to control the transmit signal to produce the reactive transmit coil voltage to be approximately constant and approximately equal to zero whilst the transmit coil current is non-zero and approximately constant for at least part of the first period; and receive electronics which are adapted and arranged to receive and process a receive magnetic field during at least some of the first period to produce an indicator output. | 01-28-2010 |
| 20100141247 | CONSTANT CURRENT METAL DETECTOR WITH DRIVEN TRANSMIT COIL - 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. | 06-10-2010 |
| 20100148781 | RECTANGULAR-WAVE TRANSMITTING METAL DETECTOR - 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. | 06-17-2010 |
| 20100148960 | METAL DETECTOR FOR SALT SOILS - 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. | 06-17-2010 |
| 20100283467 | METAL DETECTOR WITH IMPROVED MAGNETIC RESPONSE APPLICATION - 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. | 11-11-2010 |
| Patent application number | Description | Published |
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| 20100026485 | METAL DETECTOR WITH IMPROVED MAGNETIC SOIL RESPONSE CANCELLATION - A metal detector with improved magnetic soil response cancellation is disclosed. The metal detector including, in one aspect, at least one or more inductors arranged and adapted to transmit and receive an alternating magnetic field, transmit electronics arranged and adapted to generate a transmit signal applied to at least one inductor to produce a transmitted magnetic field, at least one inductor, a first inductor, arranged and adapted to receive a magnetic field to produce a receive emf signal, the said first inductor being connected to receive electronics arranged and adapted to amplify and may filter the receive emf signal to produce a receive signal, the transmit signal is arranged and adapted to contain at least three different frequency components, a relatively high frequency component, a relatively low frequency component and a relatively medium frequency component, the receive electronics is arranged and adapted to contain signal processing which may process the receive signal to produce and output indicator signal, such that at least part of the signal processing includes at least one linear combination of in effect adding receive signal components containing at least relatively high frequency resistive components to receive signal components containing at least relatively low frequency resistive components and the resultant sum is subtracted from receive signal components containing at least relatively medium frequency resistive components to give a linear combination output, coefficients of the linear combination being selected so that a further processed linear combination output which may include filtering is approximately independent of signals from magnetic soils including at least some higher order effects of different soils under the influence of the transmitted magnetic field which may include small variations in a ratio of received relatively high frequency resistive components compared to medium frequency resistive components, and also may include small variations in a ratio of received relatively medium frequency resistive components compared to lower frequency resistive components, the said linear combination arranged and adapted such that the further processed linear combination output is responsive to at least some metal targets, and the further linear combination output is arranged and adapted to produce the said output indicator signal. | 02-04-2010 |
