Patent ID: 9537677
Date: 2017-01-03
CPC Classifications: H01L,H03H,H04B,H04J,H04L

Claim:
1. A set of two or more individually identifiable surface acoustic wave sensor tag devices (a) at least one piezoelectric substrate; (b) a first SAW element comprising a transducer formed on a region of said piezoelectric substrate for transducing a signal; (c) at least two additional SAW elements formed on said piezoelectric substrate; (d) a pair of acoustic wave propagation paths that are defined by the position of said SAW elements relative to the crystal axes of the substrate, wherein: (e) wherein the specified pedestal delay of each said sensor is selected from a quantized set of delays; and (f) wherein at least one of said SAW elements in each of said sensor tag devices implements at least one direct sequence spread spectrum (DSSS) code; and (g) wherein said DSSS code of each sensor is selected from a defined set of DSSS codes; and (h) wherein each of said sensor tag devices incorporates at least one operating center frequency; and (i) wherein said operating center frequency is selected from a set of discrete frequencies; and (j) wherein said set of discrete frequencies is selected such that frequency responses from devices operating at the discrete frequencies do not substantially overlap; and (k) wherein the combination of the specified pedestal delay, the operating center frequency, and the DSSS code of each sensor provides a means of discrimination between sensors for individual device identification.