Radar level meter, also known as high-frequency radar level meter, contact radar level meter, as a kind of non-contact sensor, the main working principle is to detect the microwave information reflected from the liquid surface, and then calculate the position of the object surface.

When the antenna of the radar level meter transmits electromagnetic wave, the electromagnetic wave is reflected by the liquid surface and then received by the antenna, and the time from transmitting to receiving the electromagnetic wave is proportional to the distance between the electromagnetic wave and the liquid surface. Based on the principle of time dilation technique, the time interval between the transmitting pulse and the receiving pulse is calculated, and then the distance between the antenna and the surface of the measured medium is calculated.

From the above principle of radar level meter, we can see that the main advantage of radar level meter is its fast speed, non-contact, all-weather online real-time continuous detection.

The radar level monitoring system consists of radar level meter, telemetry master control terminal, mounting bracket, solar power supply system, wireless transmission gateway, cloud platform and so on. It is suitable for real-time liquid level monitoring in river, reservoir, nullah, lake and other waters; radar level meter is based on the time domain reflection principle (TDR), according to the distance between the transmitter and the surface of the measured medium is proportional to the propagation time of the pulse in the interval, and the height of the liquid level is calculated to realize the collection of the liquid level data in the monitoring area; the data will be transmitted to the server platform through the 4G~5G wireless network, and then analyzed and processed by the platform, and then finally transmitted through the mobile platform to the server. Through 4G~5G wireless network transmission to the server platform, the platform analyzes and processes the collected data, and finally, the data can be accessed through multiple terminals, such as mobile terminal/PC terminal, forming a complete set of monitoring system integrating collection, transmission, analysis, and push.

Due to the above advantages of radar level meter, it is not affected by temperature and humidity, fog, muddy water, sludge, aquatic plants and other factors, and has high measurement accuracy. In addition, it is easy to install and easy to maintain, which is more and more recognized and applied in more and more fields.

Then radar level meter is mainly divided into the following three types:

1, repetitive frequency (FMCW) radar level meter: this type of radar level meter uses a special frequency modulation technology, called "linear frequency modulation", through the measurement of the echo time of the signal to determine the location of the object and distance. This type of radar level meter can measure the liquid level height of different media, with high accuracy, high stability, long life and other advantages.

2, frequency scanning (Pulse) radar level meter: this type of radar level meter sends a short pulse signal, and measure the time delay when it returns, so as to determine the position and distance of the object. This type of radar level meter is suitable for large containers or other applications that require measurement of longer distances, and for dust, gas, steam and other interference has a better resistance.

3, resonant (TDR) radar level meter: this type of radar level meter is based on time domain reflection (TDR) technology, by sending a pulse signal, measuring the time delay of the reflected signal to determine the liquid level height. Since cables are characterized by low cost and easy installation, resonant radar level meters usually use metal probes or wires as sensors, which need to be inserted into the liquid when measuring the level. Resonant radar level meters are suitable for level measurement of various media, and are especially good at measuring in closed vessels.