A basic ultrasonic level sensor uses ultrasonic waves to measure the level of a liquid in a container or tank. The principle behind ultrasonic level measurement is based on the time-of-flight of sound waves in the liquid.
Here's a step-by-step explanation of how it works:
Generation of Ultrasonic Waves: The sensor emits short pulses of ultrasonic waves (typically in the range of 20 kHz to 200 kHz). These waves are inaudible to the human ear but can travel through the air and liquids.
Reflection of Ultrasonic Waves: When the ultrasonic waves encounter the surface of the liquid in the tank, they get partially reflected back towards the sensor due to the difference in acoustic impedance between the liquid and the air (or any other medium present above the liquid). The rest of the energy continues to propagate through the liquid.
Receiving the Reflected Waves: The sensor has a receiver that picks up the reflected ultrasonic waves. The time taken for the waves to travel from the sensor to the liquid surface and back is measured. This time is known as the "time-of-flight."
Calculating the Liquid Level: The sensor uses the known speed of sound in the medium (usually air) and the measured time-of-flight to calculate the distance between the sensor and the liquid surface. Since the distance from the sensor to the bottom of the tank is also known, subtracting the measured distance from the total tank height gives the liquid level.
Output and Calibration: The sensor provides an output signal (often a voltage or current signal) that corresponds to the liquid level. This output can be further calibrated and scaled to provide readings in units of volume or percentage of the tank's capacity.
It's essential to consider the speed of sound in the medium (typically air) as it can be affected by temperature and humidity. Many ultrasonic level sensors have built-in compensation features to account for these environmental factors and provide accurate measurements.
Ultrasonic level sensors are commonly used in various industries for measuring liquid levels in tanks and containers, as they are non-contact, reliable, and suitable for a wide range of liquids. However, it's essential to consider factors like the nature of the liquid, tank design, and sensor installation to ensure optimal performance.