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Besançon, France

Friedt J.-M.,SENSeOR | Droit C.,FEMTO ST Institute | Martin G.,FEMTO ST Institute | Ballandras S.,FEMTO ST Institute
Review of Scientific Instruments

Monitoring physical quantities using acoustic wave devices can be advantageously achieved using the wave characteristic dependence to various parametric perturbations (temperature, stress, and pressure). Surface acoustic wave (SAW) resonators are particularly well suited to such applications as their resonance frequency is directly influenced by these perturbations, modifying both the phase velocity and resonance conditions. Moreover, the intrinsic radio frequency (rf) nature of these devices makes them ideal for wireless applications, mainly exploiting antennas reciprocity and piezoelectric reversibility. In this paper, we present a wireless SAW sensor interrogation unit operating in the 434 MHz centered ISM band-selected as a tradeoff between antenna dimensions and electromagnetic wave penetration in dielectric media-based on the principles of a frequency sweep network analyzer. We particularly focus on the compliance with the ISM standard which reveals complicated by the need for switching from emission to reception modes similarly to radar operation. In this matter, we propose a fully digital rf synthesis chain to develop various interrogation strategies to overcome the corresponding difficulties and comply with the above-mentioned standard. We finally assess the reader interrogation range, accuracy, and dynamics. © 2010 American Institute of Physics. Source

Friedt J.-M.,SENSeOR
2013 Joint European Frequency and Time Forum and International Frequency Control Symposium, EFTF/IFC 2013

The flexibility, reconfigurability and stability of software defined radio yield an attractive alternative to the analog strategy of probing acoustic transducers acting as passive sensors probed through a wireless link or to phase noise characterization of oscillators. However, developing processing blocks is a time consuming activity, yet metrology applications require a dedicated understanding of each processing step. We consider GNURadio as a means of exploiting opensource software as an optimum tradeoff between software re-usability yet compatible with an audit for assessing performance. This signal processing environment is demonstrated on two practical examples, FMCW probing of acoustic delay lines acting as sensors, and quartz tuning fork characterization. Both examples are considered as introductory setups for training and teaching yet a suitable environment for research activities. © 2013 IEEE. Source

A method of interrogating a surface acoustic wave differential sensor formed by two resonators is provided, wherein the method allows the measurement of a physical parameter by determination of the difference between the natural resonant frequencies of the two resonators, which difference is determined on the basis of the analysis of a signal representative of the level of a signal received as echo of an interrogation signal, for a plurality of values of a frequency of the interrogation signal in a domain of predetermined values; the analysis can be based on the cross-correlation of the said signal representative of the level according to a splitting into two distinct frequency sub-bands. An advantage is that it may be implemented in a radio-modem.

Senseor and French National Center for Scientific Research | Date: 2011-04-05

A method of remotely interrogating a passive sensor, comprising at least one resonator, so as to determine the resonant frequency of said resonator, having a resonant frequency response defined by the design of said resonator, includes: a preliminary frequency-scan step for interrogating said resonator over a frequency range allowing for the rapid determination of a first resonant frequency (fr

A method of interrogating sensors of SAW type, which allows notably the gathering of physical measurements of parameters carried out by SAW sensors, the method for gathering the measurement of an SAW sensor comprising a first step of generating and emitting an electromagnetic signal corresponding to the dilated time-reversal of a dilation coefficient k, of an impulse response signature which is characteristic of the SAW sensor, a second step of gathering a signal received as echo originating from the SAW sensor, a third step of determining a maximum of cross-correlation of the signal received as echo during the second step, the first step being applied with a set of values of the dilation coefficient k in a determined domain, the measurement of a physical parameter then being determined by the dilation coefficient k for which the power or the amplitude of the signal gathered as echo is a maximum.

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