Wireless sensing using oscillator circuits locked to remote high-QSAW resonators

摘要

This paper introduces a method of wireless read out of high Qnsurface acoustic wave (SAW) resonator sensors. The resonator is excitednby a short RF pulse and decays after switching off the interrogatingnsignal. In the measurement system, a gated phase locked loop (GPLL)nlocks to the resonance frequency of the SAW resonator within a fewnbursts. Then the frequency of the GPLL oscillator is synchronized to thenresonance of the sensor and can be measured easily. The concept isnintended to yield an alternative to interrogators with expensive signalnprocessing. Considering the inherent limitations, the proposed systemnpresents a low cost solution for temperature, force, torque, etc.nmeasurements. We describe the sensors, the signals, and the implementednsystem. Results of temperature measurements using quartz resonators arenpresented, and merits and disadvantages are discussed