An algorithm for automating fast and accurate measurements of the resonance frequencies of SAW sensors

Within the context of probing acoustic wave resonators acting as wireless, passive sensors, we present an embedded interrogation unit and the associated algorithms, demonstrating the flexibility of a mostly software defined strategy. An ARM-7 based central processing unit synchronizes the narrow-band probing pulse emission, emission-to-reception switching, data sampling and data processing. Since each emitted pulse is independently defined with respect to its neighbours, flexible strategies are implemented aiming at fast (3 points needed to probe the resonant frequency, with a total duration less than 200 μs) and accurate (≃10 Hz resolution) techniques.