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 using an interrogation device, the method comprising:

• a step of emitting, from a radio signal generator of the interrogation device, 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, at an antenna of the interrogation device, a signal received as an echo from a resonator in the at least two resonators 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, at a mixer of the interrogation device, the signal received as the echo to low frequency by mixing with a radiofrequency signal whose frequency equals the frequency of the electromagnetic signal emitted,
• a filtering step, at a filter of the interrogation device, to eliminate the high frequencies of the signal mixed in the transposition step, and
• a step of determining, using calculation means, 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 the echo for each frequency sub-band as a function of the frequency of the electromagnetic signal emitted.