Maximum Measurement Range and Accuracy of SAW Reflective Delay Line Sensors

Sensors

Zehua Zheng²  Tao Han¹  Peng Qin² 

[1] Department of Instrument Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China;

关键词: SAW;    reflective delay line;    maximum phase measuring error;    maximum range;    maximum accuracy;   

DOI  :  10.3390/s151026643

来源: mdpi

【 摘 要 】

In a surface acoustic wave (SAW) wireless sensor with a reflective delay line structure, three reflectors are often used to eliminate 2π ambiguity of phase measurement. The maximum range of the measured parameter and the maximum accuracy have recently been attracting much research attention. In this paper, an analytical formula for all the factors influencing the measurement range and accuracy of the delay line SAW sensor are deduced for the first time. The factors include: the sensor sensitivity, the topology of the delay line, the available wireless bandwidth and the allowed maximum phase measuring error of the reading system, which is easier to retrieve and more fully describes the possible noises than SNR. Additionally, many designers believe that increasing the reflector could improve accuracy continuously or realize multi-resolution measurement. However, they ignore some certain criteria that the reflector location must satisfy. The reachable maximum accuracy by every increase of a reflector is also presented. A SAW temperature sensor system using 128° YX-LiNbO₃ is designed to verify the above theoretical analysis.

【 授权许可】

CC BY   
© 2015 by the authors; licensee MDPI, Basel, Switzerland.