Ultrasonic Level Meter Working Principle: The Larger the Ultrasonic Echo Quality Value, the Better the Performance

　　Ultrasonic level meter operating frequency and measurement performance: When the sensor operates at high frequency (40-70 KHz), the sensor is compact in size, has a small blind zone, good directivity, and high accuracy. However, its acoustic wave attenuates quickly, and its penetration capability is poor when the propagation medium (air) fluctuates, resulting in a shorter measurement range. When the sensor operates at low frequency (10-20 KHz), the sensor is larger in size, has a large blind zone, poor directivity, and low accuracy. Its advantage is that the acoustic wave attenuates slowly, providing better penetration when the propagation medium (air) fluctuates, allowing for a slightly longer measurement range.

　　1. The more stable the propagation medium, the more conducive it is to propagation

　　Ultrasound is a mechanical wave. During propagation, mechanical waves are affected by the stability of the propagation medium. For example: Consider a pond of water. When the water is calm, throwing a stone into the pond will create visible ripples. When strong winds cause waves on the pond, even throwing a large stone makes it difficult to see ripples. Many factors can cause air fluctuation, such as dust, air currents, steam, material flow, etc., all of which can reduce echo quality and affect measurement performance. When conditions such as dust or air currents are severe, it is recommended to use a low-frequency ultrasonic level meter for measurement.

　　2. The flatter the surface of the measured medium and the greater the acoustic impedance (the harder it is), the more conducive it is to echo reflection

　　In solid measurement, the measured surface is never perfectly flat and has a certain angle of repose. Under such conditions, the reflected wave is a diffuse reflection. Since reflection is related to wavelength, reflection can only occur when the linear dimension of the reflecting surface is comparable to or larger than the wavelength. Clearly, the higher the operating frequency, the shorter the wavelength, making diffuse reflection easier for smaller materials. For example, a mechanical wave at 10 KHz has a wavelength of 34 mm in air, and in most cases, the linear dimension of the material will not be this large. Additionally, at low-frequency operation, the emission wave has a large opening angle, resulting in a very wide echo. This makes the measured data inaccurate, sometimes off by hundreds of millimeters or even 1 meter or more. Therefore, for measuring solid level with small particle sizes, it is recommended to use a high-frequency ultrasonic level meter.

　　In summary, when considering the site conditions, special attention should be paid to two aspects: the air condition between the transducer and the measured medium, and the surface condition of the measured medium.

　　Ultrasonic level meter The ultrasonic wave emitted by the sensor is reflected upon encountering the measured medium. The quality of the reflected echo reflects the application performance of the level meter. Ultrasonic echo quality is defined as the ratio of the minimum echo amplitude (the echo amplitude under the worst conditions) to the maximum noise amplitude (the amplitude of false echoes, multipath reflected echoes, etc.). The larger the ultrasonic echo quality value, the better the level meter application performance.