By recording the time pulse radar level meter, and the electromagnetic wave transmission speed is constant, the liquid can be calculated from the radar antenna to make the liquid surface level.

In practice, there are two methods of radar level meter: frequency modulation continuous wave and pulse wave. The use of frequency modulation continuous wave technology level meter, power consumption, the need to use four lines, complex electronic circuits. The use of pulse wave radar liquid level meter technology, low power consumption, can be connected to the 24V DC power supply, easy to achieve intrinsic safety, high measurement accuracy, wider scope of application.

In the ultrasonic testing technology, regardless of the kind of ultrasonic instrument, ultrasonic transmitter energy conversion was eliminated, and then switched back to the received signal, the function is called, to complete the ultrasonic transducer, also known as the probe. As shown, the ultrasonic transducer is placed above the liquid to be measured, the ultrasonic transmitter down through the air, ultrasonic medium, water is reflected and received by the transducer and converted into electrical signals in the face detection part detects the electronic signal into a signal level display and output.

It is shown that the principle of ultrasonic propagation in the medium, if the medium, temperature, density, moisture and other conditions are constant, the propagation velocity of the ultrasonic wave is constant in the medium. Therefore, when the ultrasonic wave is measured at the surface of the transmitter, the receiver receives the reflected time when you can translate the ultrasonic wave, which is the level of data.