Magnetic screening system

Abstract

A magnetic screening system uses directional gradiometers with high resolution and accuracy to measure magnetic field signatures of target objects (e.g., gun, knife, cell phone, keys) in a volume of interest. The measured signatures can be compared to signatures of known objects stored in a local database. Various mathematical processes may be used to identify or classify target object signatures. In a network of magnetic screening systems, the magnetic screening systems can transmit signatures to a central signature database, and a management computer can share the central signature database with all of the magnetic screening systems on the network. The magnetic screening system can operate in multiple modes, such as a tracking mode, measurement mode, and self-test mode. Through use of unique processes and designs, the magnetic screening system can achieve a high rate of processing persons for target objects.

1 . A magnetic screening system, comprising: 
 an arrangement of gradiometers each including at least three magnetometers;    a gradiometer processor in communication with the magnetometers that scales outputs from the magnetometers with unequal weights and combines the scaled outputs to orient a direction of sensitivity of the respective gradiometer toward a volume of interest; and    at least one arrangement processor in communication with the arrangement of gradiometers that uses the gradiometers in a collective manner to detect a target object.    
   
   
       2 . The magnetic screening systems according to  claim 1  wherein the arrangement of gradiometers define a portal.  
   
   
       3 . The system according to  claim 1  wherein the at least one arrangement processor localizes a position of the target object.  
   
   
       4 . The system according to  claim 1  wherein the at least one arrangement processor identifies the target object.  
   
   
       5 . The method according to  claim 1  wherein the at least one arrangement processor classifies the target object.  
   
   
       6 . The system according to  claim 1  wherein the arrangement of gradiometers define at least one boundary of the volume of interest.  
   
   
       7 . The system according to  claim 1  wherein each gradiometer senses a local disturbance in a magnetic field in an electromagnetically passive manner.  
   
   
       8 . The system according to  claim 1  further including a target object signature database, and wherein the at least one arrangement processor is in communication with the signature database and compares measurements by the arrangement of gradiometers against signatures of target objects stored in the signature database.  
   
   
       9 . A method for operating a magnetic screening system, comprising: 
 applying unequal weights to outputs of at least three magnetometers in a gradiometer in an arrangement of gradiometers;    combining the unequally weighted outputs to orient a direction of sensitivity toward a volume of interest; and    using the gradiometers in a collective manner to detect a target object.    
   
   
       10 . The method according to  claim 9  wherein the arrangement of gradiometers define a portal.  
   
   
       11 . The method according to  claim 9  further including localizing a position of the target object based on measurements by the gradiometers.  
   
   
       12 . The method according to  claim 9  further including identifying the target object based on measurements by the gradiometers.  
   
   
       13 . The method according to  claim 9  further including classifying the target objects based on measurements by the gradiometers.  
   
   
       14 . The method according to  claim 9  wherein orienting a direction of sensitivity toward a volume of interest includes orienting a direction of sensitivity toward a pathway defined by a boundary including at least a subset of gradiometers of the arrangement of gradiometers.  
   
   
       15 . The method according to  claim 9  further including sensing a local disturbance in a magnetic field in an electromagnetically passive manner.  
   
   
       16 . The method according to  claim 9  further including comparing measurements of a target object signature by the arrangement of gradiometers to known target object signatures to identify the target object.  
   
   
       17 . A magnetic screening system, comprising: 
 means for applying unequal weights to outputs at least three magnetometers in a gradiometer in an arrangement of gradiometers;    means for combining the unequally weighted outputs to orient a direction of sensitivity toward a volume of interest; and    means for using the gradiometers in a collective manner to detect a target object.