Patent attributes
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 (fr0) 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 (f11) and a second frequency (f21) such that: f11=fr0−fm/2 and f21=fr0+fm/2, fm being smaller than the width at half-maximum of the resonant frequency response defined by the design, allowing a first couple of amplitudes (Pf11, Pf21) of first and second reception signals to be defined; a second step of determining the amplitude difference (Δ(Pf11−Pf21)), said difference being signed; a third step allowing a first resonant frequency (fr1), controlled by said signed amplitude difference, to be defined and having the formula fr1=fr0+K*[Δ(Pf11−Pf21)−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 (fri+1) from an ith resonant frequency (fri) having the formula: fri+1=fri+K*[Δ(Pf1i−Pf2i)−Ca], so as to obtain a determined resonant frequency (fri+1) such that the signed amplitude difference (Δ(Pf1i−Pf2i)) is equal to the control set-point (Ca).
