System and method for determining the level of a substance in a container based on measurement of resonance from an acoustic circuit that includes unfilled space within the container that changes size as substance is added or removed from the container

Abstract

Level of a substance in a container can be determined by exciting vapor in unfilled space within the container. Variable frequency oscillator and emitting transducer can provide signals to excite resonance of vapor. A sensor can measure the peak resonant signal of vapor excited in unfilled space within the container as the amount of substance in the container changes. A signal-processing unit coupled to the sensor and variable frequency oscillator can process signals sensed by the sensing transducer and can extract them from background noise affecting the acoustic signal of the system using correlation functions by referencing the signal generated by the variable frequency oscillator. A computer can obtain the signal processed by the signal-processing unit and calculate unfilled space within the container and derive therefrom an amount of filled space representing the amount of the substance contained therein. A gauge can indicate the amount of substance in the container.