Importance

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Abstract

An ultrasonic transducer for measuring a property of a material within a defined space has a function of a velocity at which ultrasonic signals travel through the defined space includes a controller. The controller is adapted for coupling to a plurality of ultrasonic transducers. The controller include a multiplexer for selecting one of the plurality of ultrasonic transducers, signal processing means for processing an output of the selected ultrasonic transducer and controller means for providing parameters to the signal processing means based upon the selected ultrasonic transducer. The controller couples to a two wire 4-20 mA communication loop. The controller periodically excites the ultrasonic transducer to obtain a measurement. The controller stores power received from the two wire communication loop and excites the transducer using stored power. The controller is capable of providing power which exceeds that available directly from the two wire communication loop for a brief period of time. The controller provides a wet self-test whereby output level of the ultrasonic transducer is monitored while strength of the excitation signal provided to the ultrasonic transducer is decreased. The amount of decrease required for the output signal to pass a threshold level is an indication of the usefulness of the sensor.

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First Claim