Remote acoustic wave sensors

Abstract

Disclosed is an acoustic wave sensor, including an acoustic wave oscillator having a resonant frequency which is modulated according to changes in a physical variable and a broadcast amplifier for directly transmitting the modulated frequency as a radio frequency signal. As a surface acoustic wave pressure sensor, the sensor includes a housing defining a cavity therein, an opening in the housing communicating with the cavity, a surface acoustic wave transducer attached to the housing to close the opening and adapted to deflect in response to a pressure differential across the transducer, an amplifier coupled to the transducer in a feedback loop, the transducer thereby being adapted to modulate the resonant frequency of the loop in response to the deflection, and a broadcast amplifier for directly transmitting the modulated frequency as a radio frequency signal. As a Stoneley acoustic wave pressure sensor, the sensor includes a housing defining a cavity therein, an opening in the housing communicating with the cavity, a Stoneley acoustic wave transducer attached to the housing to close the opening and adapted to deflect in response to a dynamic pressure differential across the transducer, an orifice in the housing communicating with the cavity to equalize any static pressure differential, an amplifier coupled to the transducer in a feedback loop, the transducer thereby being adapted to modulate the resonance frequency of the loop in response to the deflection, and a broadcast amplifier for directly transmitting the modulated frequency as a radio frequency signal.