Abstract: An improved ultrasonic system for detecting the level of a material that has a surface, for example a liquid level inside of a tank, which improves the ability to detect levels particularly when the tank is nearly full. A transmitted ultrasonic signal from a transducer is reflected against the material in the tank, and when received back at the transducer, an output pulse is provided from the transducer. The distance or level is determined by determining the time between the transmission and the reflected signal. A comparator compares the signal from the transducer with a reference and provides an output when a pulse of greater magnitude than the reference is received.