On-site manual measurement was the most common method of river water level monitoring before the emergence of ultrasonic flow meters. However, with the development of technology, the shortcomings of this simple and primitive method have become more and more obvious. The measurement error is relatively large, vulnerable to bad weather, more manual labor is required to monitor multiple field data per day, and the danger of measuring at river banks up to 5 meters deep is high. However, with the introduction of ultrasonic level meter, its easy-to-use, accurate measurement, and the ability to be applied in various complex working conditions and outdoor environments, it has gradually replaced the manual detection method and become the main way of water level monitoring. So what are the measurement methods of ultrasonic level meter? How is its application in water level monitoring?

I. Common measurement methods of ultrasonic sensors

　　Ultrasonic sensors achieve monitoring of liquid level through the time required for transmitting and receiving and the conversion of level or distance, which is widely used in the field of liquid level measurement due to its simplicity, stability and reliability. At present, the more common methods of ultrasonic level measurement mainly include resonance method, frequency difference method, ultrasonic attenuation method, ultrasonic pulse echo method, etc.

　　1、Resonance method

　　Resonance method is based on the principle of adjusting the frequency of ultrasonic waves to establish a standing wave resonance state between the probe and the liquid surface. As the spacing between the probe and the liquid surface is proportional to the wavelength of ultrasound in the medium, when the ultrasound velocity is known, the wavelength can be calculated from the resonant frequency and can be converted from the probe to the distance from the liquid surface.

　　2、Frequency difference method

　　Frequency difference method is sent through the ultrasonic probe frequency modulation ultrasound, ultrasound frequency with the propagation distance, and can be based on the frequency difference between the received signal and the sent signal to obtain from the time sent to the received.

　　3、Ultrasonic attenuation method

　　The so-called ultrasonic attenuation measurement method is to use the principle that the attenuation of ultrasonic waves in the measurement medium varies with distance, and the level of the ultrasonic level sensor wholesale measures the level according to the attenuation change between the received signal and the transmitted signal.

　　4、Ultrasonic pulse-echo method

　　Ultrasonic pulse echo method is to use the principle of ultrasonic probe emitting ultrasonic pulse for liquid level measurement. When the ultrasonic wave encounters an obstacle, the ultrasonic wave will be reflected back. According to the ultrasonic wave in the current environment, the time of ultrasonic wave transmission and the time of receiving the return wave are recorded by the microcontroller. By the formula S=C×t/2 (where S is the measurement distance, C is the ultrasonic wave propagation speed and t is the echo time), the height of the liquid level can be measured.

　　From the above comparison of ultrasonic measurement methods, it is easy to see that the frequency difference method requires a frequency modulator to generate the modulation frequency, the attenuation method needs to measure the attenuation of ultrasonic waves, and the resonance method detects the liquid level subject to certain specific conditions and requires a standing wave relationship with the liquid surface, which is a contact measurement method. In contrast, the ultrasonic pulse-echo method does not require the establishment of standing waves with the liquid surface, and can achieve non-contact detection. Therefore, ultrasonic pulse echo method of water level monitoring is the most suitable one among several measurement methods.

Second, kaidiSL series ultrasonic level meter in the application of water level monitoring

　　kaidiSL series ultrasonic level meter is the use of ultrasonic pulse echo method to achieve the level measurement, specifically the ultrasonic level meter transducer (probe) emits a high-frequency ultrasonic pulse, when encountering the measured level surface, the sound waves are reflected back, part of the reflected echo is received by the transducer (probe) and converted into an electrical signal, the user can know the water level based on the reflected signal almost in real time.

　　When choosing the instrument for water level measurement, here we recommend kaidiSL series ultrasonic level transmitter, which adopts microprocessor program control technology and intelligent signal processing technology for efficient and accurate measurement. The high explosion-proof level (Ex d IIC T6 Gb) and the PVDF material probe make it very suitable for application in corrosive liquids and harsh working conditions, strong interference and noisy outdoor environment.

In addition, kaidiSL series ultrasonic level meter has a variety of ranges to choose from and can measure up to 15 meters, which is ideal for long-distance detection and water tank level detection.

　　Local related departments can quickly deploy flood monitoring systems based on the feedback data from ultrasonic level meters, which has high economic benefits. The meter can be installed on bridges, rivers, streams and anywhere a remote monitoring system needs to be installed. Early warning systems will alert you that water levels are rising in order to protect people and communities from flooding.

　　In addition to using ultrasonic level meters for water level monitoring, users can also use radar, depth level sensors and other technologies to monitor water levels. The use of ultrasonic level meters is a low-maintenance and widely used level measurement instrument available today. Users can accurately obtain all the required data, and has a high cost performance, quite popular with the majority of users.