The level meter is composed with the designed in the integrative ultrasonic wave sensor and electronic unit. The level meter installs on the top of the container, under the control of the electronic unit, the sensor launches a bunch of ultrasonic pulses to the tested. Sound wave is reflected by object surface, parts of reflected return waves echo are received and change into the electric signal. The time of launching ultrasonic wave to the receiving it again is direct ratio to the distance of sensor to the things of tested. The electronic unit measures the time, and calculate out the distance examined according to the known velocity of sound. Then draw the location value of things through subtraction operation.
