A basic ultrasonic level sensor measures liquid levels using ultrasonic sound waves. It operates on the principle of emitting an ultrasonic pulse and measuring the time it takes for the pulse to travel to the liquid surface and return after being reflected by the surface. This time measurement is then used to calculate the distance from the sensor to the liquid surface, which is a direct indicator of the liquid level.
Here's a step-by-step explanation of how a basic ultrasonic level sensor works:
Transmitter Emission: The sensor emits a short burst of high-frequency sound waves (ultrasonic pulses). These pulses typically have a frequency in the range of 20 kHz to 200 kHz, which is above the range of human hearing.
Wave Propagation: The ultrasonic pulse travels through the air towards the liquid surface. As the pulse encounters the air-liquid interface, part of the pulse is reflected back towards the sensor.
Reflected Pulse Detection: The sensor's receiver detects the reflected pulse that returns after bouncing off the liquid surface. The time it takes for the pulse to travel to the liquid surface and return is measured accurately.
Time-of-Flight Calculation: By knowing the speed of sound in air (which is approximately 343 meters per second at room temperature) and using the measured time it took for the pulse to travel to the surface and back, the sensor calculates the total time of flight of the ultrasonic pulse.
Distance Calculation: The distance between the sensor and the liquid surface is calculated using the formula:
Distance = (Speed of Sound × Time of Flight) / 2
Dividing by 2 accounts for the two-way travel of the ultrasonic pulse.
Liquid Level Determination: The calculated distance is used to determine the liquid level within the container. This level can be directly displayed on the sensor's output or transmitted to a control system for further processing.
It's important to note that certain factors, such as temperature, humidity, and air turbulence, can affect the speed of sound in the air and thus impact the accuracy of the distance measurement. To mitigate these effects, some ultrasonic level sensors incorporate compensation mechanisms and advanced algorithms.
Ultrasonic level sensors are commonly used for various applications, including industrial processes, storage tanks, water treatment systems, and more, due to their non-contact measurement capability and relatively simple installation.