Patent ID: 8441168

Claim:
A coded surface acoustic wave device, comprising (a) a piezoelectric substrate; (b) one first transducer arranged on at least a portion of said piezoelectric substrate wherein said first transducer has electrode structures that vary in width and separation along the transducer in the direction of acoustic wave propagation so as to be capable of interacting with a received spread spectrum signal to at least partially compress said received spread spectrum signal into a signal that is shorter in time, and to generate and receive acoustic waves on the substrate corresponding to said shorter signal; (c) at least one second surface acoustic wave element formed on said piezoelectric substrate and spaced from and not in electrical contact with said first transducer along the direction of acoustic wave propagation, said at least one second surface acoustic wave element comprising sub elements, each of which comprises electrode structures capable of interacting with acoustic waves at frequencies that correspond to at least a subset of the frequencies generated by said first transducer; (d) wherein said sub-elements of said at least one second surface acoustic wave element are spatially distributed along said piezoelectric substrate in the direction of acoustic wave propagation; and wherein said at least one second surface acoustic wave element is structured such that said sub-elements of said second surface acoustic wave element are spaced at different positions in the direction of acoustic wave propagation relative to the corresponding portion of said first transducer, so as to effect different delays to each of said sub-elements, thereby effecting a code.