Title :
Orthogonal frequency coding for SAW tagging and sensors
Author :
Puccio, Derek ; Malocha, Donald C. ; Saldanha, Nancy ; Gallagher, Daniel R. ; Hines, Jacqueline H.
Author_Institution :
Dept. of Electr. & Comput. Eng., Central Florida Univ., Orlando, FL, USA
Abstract :
Surface acoustic wave (SAW)-based sensors can offer wireless, passive operation in numerous environments, and various device embodiments are used for retrieval of the sensed data information. Single sensor systems typically can use a single carrier frequency and a simple device embodiment because tagging is riot required. In a multisensor environment, it is necessary to both identify the sensor and retrieve the sensed information. This paper presents the concept of orthogonal frequency coding (OFC) for implications to SAW sensor technology. The OFC offers all advantages inherent to spread spectrum communications, including enhanced processing gain and lower interrogation power spectral density (PSD). It is shown that the time ambiguity in the OFC compressed pulse is significantly reduced as compared with a single frequency tag having the same code length, and additional coding can be added using a pseudo-noise (PN) sequence. The OFC approach is general and should be applicable to many differing SAW sensors for temperature, pressure, liquid, gases, etc. Device embodiments are shown, and a potential transceiver is described. Measured device results are presented and compared with coupling of modes (COM) model predictions to demonstrate performance. Devices then are used in computer simulations of the proposed transceiver design, and the results of an OFC sensor system are discussed.
Keywords :
pseudonoise codes; sensor fusion; spread spectrum communication; surface acoustic waves; SAW tagging; coupling of modes model; multisensor environment; orthogonal frequency coding; power spectral density; pseudo-noise sequence; spread spectrum communications; surface acoustic wave; Acoustic sensors; Acoustic waves; Frequency; Information retrieval; Sensor systems; Surface acoustic wave devices; Surface acoustic waves; Tagging; Temperature sensors; Transceivers; Computer-Aided Design; Equipment Design; Equipment Failure Analysis; Information Storage and Retrieval; Product Labeling; Radio Waves; Telecommunications; Telemetry;
Journal_Title :
Ultrasonics, Ferroelectrics, and Frequency Control, IEEE Transactions on
DOI :
10.1109/TUFFC.2006.1593376