Reader and response control system for discrimination between multiple surface acoustic wave identification tags and method of operation thereof

Abstract

The present invention provides a system for discriminating between coded responses from multiple SAW identification tags and a method of operating such system. In one embodiment the system provides for (1) a SAW tag reader subsystem that detects coded responses from the tags to an interrogation pulse; and (2) a coded response analyzing subsystem, coupled to the SAW tag reader subsystem, that employs signal processing techniques to separate portions of the coded responses and generates possibilities for remaining portions of the coded responses.

What is claimed is:  
     
         1 . A surface acoustic wave (SAW) identification tag for hierarchical discrimination, comprising: 
 a piezoelectric substrate having located thereon a SAW transducer; and    a group of reflectors arranged on said piezoelectric substrate by time position relative to said transducer to encode a number identifying the hierarchical order of an object by said time position.    
     
     
         2 . The SAW identification tag as recited in  claim 1  wherein said hierarchical order is determined by a time differential between said transducer's propagation of an interrogation pulse and receipt of a reflected pulse from said group of reflectors.  
     
     
         3 . The SAW identification tag as recited in  claim 1  wherein said hierarchical order is comprised of an object, a package, and a pallet.  
     
     
         4 . The SAW identification tag as recited in  claim 3  wherein said hierarchical order is comprised of related items.  
     
     
         5 . The SAW identification tag as recited in  claim 1  wherein signal processing techniques are used to determine said hierarchical order.  
     
     
         6 . The SAW identification tag as recited in  claim 5  wherein at least one of said signal processing techniques is signal elimination.  
     
     
         7 . The SAW identification tag as recited in  claim 1  wherein said hierarchical order is comprised of at least two levels.  
     
     
         8 . A method to discriminate hierarchically between coded responses from multiple SAW identification tags, comprising: 
 generating an interrogation pulse from a SAW transducer located on a piezoelectric substrate; and    receiving a reflected pulse from a group of reflectors arranged on said piezoelectric substrate by time position relative to said transducer to encode a number identifying the hierarchical order of an object by said time position.    
     
     
         9 . The method as recited in  claim 8  wherein said hierarchical order is determined by a time differential between said transducer's propagation of said interrogation pulse and the receipt of said reflected pulse.  
     
     
         10 . The method as recited in  claim 8  wherein said hierarchical order is comprised of an object, a package, and a pallet.  
     
     
         11 . The method as recited in  claim 10  wherein said hierarchical order is comprised of related items.  
     
     
         12 . The method as recited in  claim 8  wherein said signal processing techniques are used to determine said hierarchical order.  
     
     
         13 . The method as recited in  claim 12  wherein said at least one of said signal processing techniques is signal elimination.  
     
     
         14 . The method as recited in  claim 12  wherein said hierarchical order is comprised of at least two levels.  
     
     
         15 . A method of operating a system for hierarchical discrimination, comprising: 
 locating a SAW identification tag on an object, said SAW identification tag having a piezoelectric substrate with a SAW transducer thereon; and    arranging a group of reflectors on said piezoelectric substrate by time position relative to said transducer to encode a number identifying the hierarchical order of said object by said time position.    
     
     
         16 . The method as recited in  claim 15  wherein said hierarchical order is determined by a time differential between said transducer's propagation of an interrogation pulse and receipt of a reflected pulse from said group of reflectors.  
     
     
         17 . The method as recited in  claim 15  wherein said hierarchical order is comprised of said object, a package of a plurality of said object, and a pallet of a plurality of said package.  
     
     
         18 . The method as recited in  claim 17  wherein said hierarchical order is comprised of related items.  
     
     
         19 . The method as recited in  claim 15  wherein signal processing techniques are used to determine said hierarchical order.  
     
     
         20 . The method as recited in  claim 19  wherein at least one of said signal processing techniques is signal elimination.