Built-in test procedure for non-intrusive ultrasonic level sensing

摘要

A built-in test system for an ultrasonic liquid level sensor that includes a transducer assembly having an ultrasonic transducer, and a switch that will be actuated when the ultrasonic transducer is in intimate contact with a surface of a tank in which level is to be determined. Once the switch is actuated to indicate that the ultrasonic transducer is properly coupled to the surface, a test sequence is initiated to determine that the level of ultrasonic transmissions are above a certain desired threshold for a selected period of time, and after which the circuit looks for echoes to determine the depth of the liquid in the tank. Thereafter, the test sequence is repeated for each cycle of level sensing.