Ultrasonic Level Sensor Archives are used in liquid-level detection systems to detect the liquid surface level with ultrasonic waves, they are immersed in the liquid. When ultrasonic waves reflect from the interface of two media, they will return back by the laws of reflection to the transmitter probe. The distance between them is proportional to the speed of sound in media and hence gives a correct reading on the liquid level. The ultrasonic level sensor is a very accurate solid-state transducer. It produces a pulse when the difference in acoustic impedance of air and fluid reaches a certain value. And in addition, it can be used to detect distances to specific points.The sensor part of an ultrasonic transmitter &receiver system is the element which uses an ultrasonic wave to measure ranges (on standard receivers) or pulse widths (on chirp receivers).