Senseor

Centre National De La Recherche Scientifique

Christophe Droit

Jean-Michel Friedt

Sylvain Ballandras

Gilles Martin

Luc Chommeloux

Jeremy Masson

A system comprises a cavity being reflecting for RF waves and comprises at least one acoustic wave sensor exhibiting a resonance frequency band, coupled to a sensor antenna; and an interrogation/reception device for the sensor. The interrogation/reception device comprises: means for transmitting/receiving an RF signal transmitting within an interrogation frequency band comprising the resonance frequency band of the sensor; at least a first transmission/reception antenna and a second transmission antenna/reception, positioned within the cavity; means for dividing the signal into at least a first RF signal and a second RF signal, the first signal being transmitted to the first transmission/reception antenna and the second signal being transmitted to the second transmission/reception antenna; means for creating a phase-shift between the first RF signal and the second RF signal; means for analysing the power level of the received signal. An interrogation method used in the system is also provided.

System for interrogating a remotely interrogatable passive sensor integrated into a metal cavity with reduced system loss and interrogation method

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.

Method of interrogation of a differential sensor of acoustic type having two resonances and device implementing the method of interrogation

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) of said resonator by detecting the amplitude of the response signal of said resonator; a first step of a first couple of interrogations of said resonator at a first frequency (f) and a second frequency (f) such that: f=fr&#x2212;f/2 and f=fr+f/2, fbeing smaller than the width at half-maximum of the resonant frequency response defined by the design, allowing a first couple of amplitudes (Pf, Pf) of first and second reception signals to be defined; a second step of determining the amplitude difference (&#x394;(Pf&#x2212;Pf)), said difference being signed; a third step allowing a first resonant frequency (fr), controlled by said signed amplitude difference, to be defined and having the formula fr=fr+K*[&#x394;(Pf&#x2212;Pf)&#x2212;Ca], where Ca is a control set-point and K is a constant; and the reiteration of the first, second and third steps comprising the definition of an (i+1)th resonant frequency (fr) from an ith resonant frequency (fr) having the formula: fr=fr+K*[&#x394;(Pf&#x2212;Pf)&#x2212;Ca], so as to obtain a determined resonant frequency (fr) such that the signed amplitude difference (&#x394;(Pf&#x2212;Pf)) is equal to the control set-point (Ca).

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Besancon, France

Christophe Droit