An ultrasonic sensor measures the distance between two objects using pulses of high-frequency ultrasonic soundwaves. Operating on similar principles to radar systems, ultrasonic sensors can convert electrical energy into acoustic waves or vice versa, depending on the sensor and application. Ultrasonic sensors are made up of a few parts:
  • The ultrasonic transmitter, which emits the pulse
  • The ultrasonic receiver, which recaptures the returning sound
  • The ultrasonic transducer, which is an element included within the sensor and receiver.
At elobau, we are committed to providing our customers with all the resources and ultrasonic knowledge you require to understand your level sensor needs. From outstanding products to unparalleled ultrasonic sensor experience, we are here to assist you as you learn about your options and find the ultrasonic level sensor solution your operations need to run as planned.

The Working Principles of Ultrasonic Level Sensors

Ultrasonic soundwaves are characterized by frequencies of 20 kHz or higher. The average ultrasonic sensor range operates between 20 kHz and 1 MHz. The exact sensor your application requires will vary depending on the installation space, planned application, and more. To meet the needs of any industrial ultrasonic sensor need, for instance, elobau offers a variety of ultrasonic sensor configurations:

Ultrasonic Sensors’ Measurement Principle

Piezoelectric components within ultrasonic transducers are used for emitting and receiving soundwaves. The piezo elements begin to vibrate when a voltage is applied. This vibration produces high-frequency soundwaves. The target reflects these impulses, and the echo returns to the ultrasonic transducer. By measuring the time of flight the echo takes to return, the distance can be calculated using the speed of sound in the air.
The equation used is s=(t ∗c)/2 with c=344 m/s (air).

Meaning of Different Ultrasonic Frequencies

Ultrasonic waves can be high frequencies or low frequencies, requiring corresponding small or large ultrasonic transducers. Find the best ultrasonic sensor for your application’s unique properties:
ultrasonic high frequenciesultrasonic low frequenciesultrasonic high frequencies

Industrial Ultrasonic Level Sensor Applications

Many industries take advantage of ultrasonic sensor technology due to the no-contact approach to measurement. These industrial ultrasonic sensor applications include: For certain applications, including medical ultrasonic sensors, hygienic options are available.

Limitations of Ultrasonic Sensors

Ultrasonic sensors have some operational limitations. These level sensors work best in environments where the ultrasonic transducers can receive quality echoes, thus tanks with high depths or materials that absorb sounds will not be ideal for ultrasonic sensors.

Ultrasonic Transmitters & Crosstalk

Crosstalk occurs when two ultrasonic level sensors intercept one another’s signals, resulting in incorrect readings. This phenomenon can be easily avoided, however, through either synchronizing or multiplexing your ultrasonic sensor system to ensure a high level of functional safety:
  • Ultrasonic Sensor Synchronization. Ultrasonic transmitters send and evaluate all received echoes at the same time. Up to ten sensors can be connected to one another via PIN 5. Once all the ultrasonic sensors have been connected, this function can be used instantly.
  • Multiplexing Ultrasonic Sensors. In this mode, the ultrasonic sensor sends the signal consecutively, resulting in ultrasonic transducers only evaluating their own echoes. Up to four sensors can be connected to one another via PIN 5. The PIN 5 must be connected with the ground (GND) for a minimum of 5 seconds after applying the operating voltage. Multiplexing does cause a slight operational delay.
Note: not all ultrasonic sensors are available with synchronization or multiplexing abilities. Check individual ultrasonic sensor specifications carefully to ensure they meet your requirements.

Ultrasonic Transducers & Blind Zones

Ultrasonic transducers within sensors alternately emit sound waves and detect the reflected echo. Because the transducer continues vibrating after emitting a pulse, the echoes cannot be immediately received. This delay creates a blind zone where no explicit or reliable measurement can be taken. To accurately measure the distance between an ultrasonic sensor and an object, blind zones must be minimized as much as possible.

Your Expert Resource for Ultrasonic Sensors & Industrial Sensor Knowledge

elobau delivers level measurement solutions across all industries and applications. To learn more about our ultrasonic sensors, contact us today. Request a quote to get started.