Remote Control of SAW Resonators Using a Frequency-Modulation-Based Interrogation Strategy
Abstract
Within the context of probing acoustic wave resonators acting as wireless, passive sensors, we present a strategy for wireless monitoring of surface accoustic wave (SAW) resonators using a frequency modulation based interrogation method. The basic principle is the conversion of frequency modulation to amplitude modulation by the resonator through its S-11 transfer function. An ARM-7 based central processing unit synchronizes the narrow-band probing pulse emission, emission to reception switching, data sampling and data processing. A closed loop control keeps the emitted carrier frequency at the resonance frequency of the sensor: we demonstrate a resolution of 2Hz on the resonance freqeuncy identification at 1s integration time, limited by this proportional feedback loop.
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