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Minelab Patent - Constant Current Metal Detector


DolanDave

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Looks Like there is a new detector coming soon: A Constant current metal detector with driven transmit coil

I tried to put a URL in this post but it will not let me. You can look up publication number US 20140232408 A1 , filed Mar 26, 2014, and publication date Aug 21, 2014

Dave

 

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Nice. How soon? Few years of field test ;)? We need pro who translate it for normal level user lanugage ;)

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It has been well known for about a year that Minelab plans on releasing a new "Super Gold Detector" in 2015 that breaks with the SD/GP/GPX series technology. http://www.detectorprospector.com/forum/topic/209-new-minelab-flagship-super-gold-detector/

"Our next flagship gold detector will be based on new technology that we have developed and verified; technology that will dramatically improve detector performance."

Whether this patent has anything to do with it I do not know and will not worry much about. Many patents are filed, many that never see actual products related to them. Best bet is to just wait and see what gets announced in the upcoming year.

From the link above:

Constant Current Metal Detector with Driven Transmit Coil

US 20140232408

BRIEF SUMMARY OF THE INVENTION

According to a first aspect of the invention, there is provided a metal detector used for detecting a metallic target in a soil comprising: a) transmit electronics having a plurality of switches 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, the at least one non zero transmit coil reactive voltage period is different from the at least one receive period; B) a transmit coil having an inductance connected to the transmit electronics for receiving the repeating transmit signal cycle and generating a transmitted magnetic field; c) a receive coil for receiving a received magnetic field during at least one receive period and providing a received signal induced by the received magnetic field; d) one or more negative feedback loops for sensing a current in the transmit coil during the at least one receive period to provide a control signal, and based on the control signal, the one or more negative feedback loops control a magnitude of a voltage and/or duration of the at least one non zero transmit coil reactive voltage period; and e) receive electronics connected to the receive coil for processing the received signal during at least one receive period to produce an indicator output signal, the indicator output signal including a signal indicative of the presence of a metallic target in the soil; wherein when the inductance of the transmit coil is modulated by the soil during an operation of the metal detector, the one or more negative feedback loops change the magnitude of a voltage and/or duration of the at least one non zero transmit coil reactive voltage period to maintain an average value of the current during at least one receive period in a cycle to be substantially the same value as an average value of the current during at least one receive period in any other cycle.

According to a second aspect of the invention, there is provided a method for detecting a metallic target in a soil using a metal detector, the method comprising: a) 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, the at least one non zero transmit coil reactive period is different from the at least one receive period; B) receiving the repeating transmit signal cycle using a transmit coil having an inductance connected to the transmit electronics for generating a transmitted magnetic field; c) receiving a received magnetic field using a receive coil during at least one receive period and providing a received signal induced by the received magnetic field; d) sensing a current in the transmit coil during at least one receive period to provide a control signal, and based on the control signal, controlling a magnitude of a voltage and/or duration of the at least one non zero transmit coil reactive voltage period; and e) processing the received signal during at least one receive period to produce an indicator output signal, the indicator output signal including a signal indicative of the presence of a metallic target in the soil; wherein when the inductance of the transmit coil is modulated by the soil during an operation of the metal detector, the step of controlling a magnitude of a voltage and/or duration of the at least one non zero transmit coil reactive voltage period includes changing the magnitude of a voltage and/or duration of the at least one non zero transmit coil reactive voltage period to maintain an average value of the current during at least one receive period in a cycle to be substantially the same value as an average value of the current during at least one receive period in any other cycle.

According to a third aspect of the invention, there is provided a computer readable medium comprising instructions for causing a processor to implement the method of the second aspect.

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