From the principle of ultrasonic propagation in the medium, it can be known that if the medium pressure, temperature, density, humidity and other conditions are constant, the propagation speed of ultrasonic waves in the medium is a constant. Therefore, when the time required for the ultrasonic wave to be received from the time it is transmitted to the time it encounters the liquid surface reflection is measured, the distance the ultrasonic wave passes through can be converted, that is, the data of the liquid level is obtained.
The radar level gauge records the time elapsed by the pulse wave, and the transmission speed of the electromagnetic wave is constant, the distance from the liquid level to the radar antenna can be calculated, so as to know the liquid level of the liquid level.
In practical applications, there are two types of radar level gauges, namely, the frequency-modulated continuous wave type and the pulse wave type. The liquid level gauge using frequency modulation continuous wave technology has high power consumption, must use a four-wire system, and the electronic circuit is complex. The liquid level gauge using radar pulse wave technology has low power consumption and can be powered by two-wire 24V DC, which is easy to implement and has high quality and wider application range. Ultrasound uses sound waves, while radar uses electromagnetic waves. This is the biggest difference. Moreover, the penetration ability and directionality of ultrasonic waves are much stronger than that of electromagnetic waves, which is why ultrasonic detection is more popular now.
Differences in main applications:
· Radar measurement range is much larger than ultrasonic.
· Radar has horn type, rod type and cable type, which can be applied to more complex working conditions than ultrasonic.
· Ultrasonic is not as accurate as radar.
· Radar is relatively expensive.
· Consider the dielectric constant of the medium when using radar.
· Ultrasonic cannot be used in vacuum, high steam content or foam on the liquid surface
