Vibrating mechanical structure characterization is demonstrated using contactless techniques best suited for mobile and rotating equipments. Fast measurement rates are achieved using Field Programmable Gate Array (FPGA) devices as real-time digital signal processors. Two kinds of algorithms are implemented on FPGA and experimentally validated in the case of the vibrating tuning fork. A first application concerns in-plane displacement detection by vision with sampling rates above 10 kHz, thus reaching frequency ranges above the audio range. A second demonstration concerns pulsed-RADAR cooperative target phase detection and is applied to radiofrequency acoustic transducers used as passive wireless strain gauges. In this case, the 250 ksamples/s refresh rate achieved is only limited by the acoustic sensor design but not by the detection bandwidth. These realizations illustrate the efficiency, interest, and potentialities of FPGA-based real-time digital signal processing for the contactless interrogation of passive embedded probes with high refresh rates.

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This work presents a comparison between three different High-overtone Bulk Acoustic Resonators based on different materials. Furthermore, the goal of this work is to realize a High-overtone Bulk Acoustic Resonators presented a temperature coefficient of frequency less than 10 ppm over a wide range of temperature around a turnover temperature, and a Q.f product higher than 5×10 13 Hz. After a discussion about the choice of materials to achieve such resonator and the description of our microfabrication, three High-overtone Bulk Acoustic Resonators based on a Lithium of Niobate, Quartz, Lithium of Tantalate, AlN and Sapphire materials are compared in term of the temperature coefficient of frequency, the Q.f product and the phase noise. The new HBAR exhibits a Q.f product around 3.7×10 13 Hz, a turnover around 55°C with a parabolic shape and a temperature coefficient of frequency around +/-4 ppm/K.