Patent ID: 7966136

Claim:
A level sensor comprising: a first transducer configured to generate a first signal and including a first output surface that is substantially parallel to a base surface; a second transducer configured to generate a second signal and including a second output surface that is substantially parallel to the base surface, wherein the base surface supports the first transducer and the second transducer; a reference target placed a first distance from the first transducer and a second distance from the second transducer; and a processor configured to switch operation between a first mode and a second mode, and to receive information from the first and second transducers, in the first mode, the processor is configured to send a first control signal to the first transducer to cause the first transducer to generate the first signal, and receive a signal from the second transducer that is based upon a reflection of the first signal from a surface; in the second mode, the processor is configured to send a second control signal to the second transducer to cause the second transducer to generate the second signal, wherein the second control signal is output at a different time than the first control signal, and receive a signal from the first transducer that is based upon a reflection of the second signal from the reference target, the processor further configured to determine a distance to the surface based on information related to the reflection of the first signal from the surface and the reflection of the second signal from the reference target.