Puccio Derek, Malocha Donald C, Saldanha Nancy, Gallagher Daniel R, Hines Jacqueline H
Electrical and Computer Engineering Department, University of Central Florida, Orlando, FL 32816-2450, USA.
IEEE Trans Ultrason Ferroelectr Freq Control. 2006 Feb;53(2):377-84. doi: 10.1109/tuffc.2006.1593376.
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.
基于表面声波（SAW）的传感器能够在众多环境中实现无线、无源运行，并且采用了各种器件实施方式来获取传感数据信息。单传感器系统通常可以使用单一载波频率和简单的器件实施方式，因为无需进行标签识别。在多传感器环境中，既需要识别传感器，又需要获取传感信息。本文提出了正交频率编码（OFC）概念，用于SAW传感器技术应用。OFC具备扩频通信所固有的所有优势，包括增强的处理增益和更低的询问功率谱密度（PSD）。结果表明，与具有相同码长的单频标签相比，OFC压缩脉冲中的时间模糊度显著降低，并且可以使用伪噪声（PN）序列添加额外编码。OFC方法具有通用性，应适用于许多不同的用于温度、压力、液体、气体等的SAW传感器。展示了器件实施方式，并描述了一种潜在的收发器。给出了测量的器件结果，并与模式耦合（COM）模型预测结果进行比较以证明性能。然后将器件用于所提出的收发器设计的计算机模拟中，并讨论了OFC传感器系统的结果。
