Method of Interrogation of a Differential Sensor of Acoustic Type Having Two Resonances and Device Implementing the Method of Interrogation

A method of interrogating a sensor comprising at least two resonators whose natural resonant frequency is dependent on a physical parameter, the method comprising:

• a step of emitting an electromagnetic signal whose frequency is varied in a frequency band by increments of determined value, from a predetermined minimum value to a predetermined maximum value, the frequency band being split into two frequency sub-bands, each frequency sub-band containing at least the expected values respectively of each natural resonant frequency of the two resonators,
• a step of gathering a signal received as echo after a determined duration after the emission carried out in the emission step, for each frequency of the electromagnetic signal emitted,
• a step of transposing the signal received as echo to low frequency by mixing with a radiofrequency signal whose frequency equals the frequency of the electromagnetic signal emitted,
• a filtering step making it possible to eliminate the high frequencies of the signal mixed in the transposition step,
• a step of determining the difference between the respective natural resonant frequencies of the said two resonators, on the basis of the cross-correlation maximum of the characteristics constituted by the level of the signal received as echo for each frequency sub-band as a function of the frequency of the electromagnetic signal emitted.