Reconfigurable Induction Coil for Metal Detection
With an estimated 100 million mines and countless millions of acres of land contaminated with unexploded ordnance (UXO) world- wide there is a need for a sensor system and methods that can detect and identify large and small metal objects buried in the soil. In addition, during armed conflict, there is a need for mine detection and neutralization in real-time or near real time. A commonly used sensor for mine and UXO detection is the electromagnetic induction (EMI) metal detector. Conventional EMI detectors using either frequency-domain (FD) or time-domain (TD) eddy current methods can detect small targets at shallow depths and large metal targets at deeper depths. However other metal objects commonly found in the environment form a major problem in identifying mines and create many false alarms. These false alarms cost time and money when trying to clear an area of the real mines. Metal targets need to not only be identified but also classified in real-time.
The Johns Hopkins University Applied Physics Laboratory has developed and is in the process of patenting a Pulse induction metal detector (PMID) that can selectively change the receiver coil configuration from a differential configuration good for detecting and classifying smaller metal objects to a summing configuration good for detecting and classifying large metal objects. A transmitter coil induces eddy currents in a nearby metal target. The operator can then select to configure the receiver coil in a differential or summing configuration. A switch coupled with the receiver coil that switches couplings in the receiver coil to create either the differential or summing configuration achieves the conversion from one mode to the other. A computer can be coupled with the switch for assisting the operator in controlling the switch setting.
US 7,157,913 [MORE INFO
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