Shi Ruchuan, Ruan Jingping, Lv Jiashi, Zhang Chenrui, Han Tao, Qin Peng, Li Ping, Wen Yumei
IEEE Trans Ultrason Ferroelectr Freq Control. 2020 Jun;67(6):1258-1266. doi: 10.1109/TUFFC.2019.2933435. Epub 2019 Aug 6.
The resolution of phase difference ambiguity is critically important for simultaneously achieving wide range and high accuracy sensing with surface acoustic wave (SAW) reflective delay-line sensors. A novel scheme called dual-frequency interrogation and hierarchical evaluation (DFI-HE) is proposed to resolve integer ambiguity of phase difference and obtain precise time delay between reflectors. With DFI-HE, only two reflectors are needed as the sensing elements for SAW reflective delay-line sensors. Additionally, DFI-HE has the advantage of fast ambiguity resolution to enable both a wide range and high accuracy sensing. The basic principle of sensing with DFI-HE is elaborated, and simulations and temperature sensing experiments are carried out to verify the proposed scheme, based on a SAW reflective delay-line temperature sensor with two reflectors fabricated on 128° YX-LiNbO substrate. The experimental results demonstrate that the temperature measurement accuracy reaches ±2 °C in the range of 8 °C-300 °C.
