A
Anonymous
Guest
DISCLOSURE
This invention comprises means for determining the ferrous or nonferrous character of targets, as a feature to be added to or integrated with an induction balance pulse induction metal detector.
Normally in an IB PI, the receiver coil is loaded only with a damping resistor, and signals received during transmit/flyback are not demodulated. This allows the detector to largely ignore ground minerals, but creates difficulty in distinguishing between ferrous and nonferrous metal targets.
If it is desired to demodulate reactive signals, an electronic switch can be provided which will short out the receiver coil during a desired portion of the transmit/flyback period, and perhaps longer, depending on the design. The switch is then opened at a time which will allow the current induced by the target to be dropped across a load and detected by the receiver.
In one preferred embodiment, a load capacitor is provided to reduce the voltage and to extend the duration of the signal to be received.
In another embodiment, the reactive system is enabled preferably every other pulse, the demodulators being synchronized similarly in order to provide separate all-metals and reactive baseband signals which can potentially be used for reactive ground balancing and/or discrimination and/or identification of targets, the principles and means for which are well known in this industry.
--Dave J.
This invention comprises means for determining the ferrous or nonferrous character of targets, as a feature to be added to or integrated with an induction balance pulse induction metal detector.
Normally in an IB PI, the receiver coil is loaded only with a damping resistor, and signals received during transmit/flyback are not demodulated. This allows the detector to largely ignore ground minerals, but creates difficulty in distinguishing between ferrous and nonferrous metal targets.
If it is desired to demodulate reactive signals, an electronic switch can be provided which will short out the receiver coil during a desired portion of the transmit/flyback period, and perhaps longer, depending on the design. The switch is then opened at a time which will allow the current induced by the target to be dropped across a load and detected by the receiver.
In one preferred embodiment, a load capacitor is provided to reduce the voltage and to extend the duration of the signal to be received.
In another embodiment, the reactive system is enabled preferably every other pulse, the demodulators being synchronized similarly in order to provide separate all-metals and reactive baseband signals which can potentially be used for reactive ground balancing and/or discrimination and/or identification of targets, the principles and means for which are well known in this industry.
--Dave J.