Orthogonal frequency coding for SAW tagging and sensors

    Authors

    D. Puccio; D. C. Malocha; N. Saldanha; D. R. Gallagher;J. H. Hines

    Comments

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    Abbreviated Journal Title

    IEEE Trans. Ultrason. Ferroelectr. Freq. Control

    Keywords

    SYSTEMS; Acoustics; Engineering, Electrical & Electronic

    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 not 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 applications 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.

    Journal Title

    Ieee Transactions on Ultrasonics Ferroelectrics and Frequency Control

    Volume

    53

    Issue/Number

    2

    Publication Date

    1-1-2006

    Document Type

    Article

    Language

    English

    First Page

    377

    Last Page

    384

    WOS Identifier

    WOS:000235323000014

    ISSN

    0885-3010

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