Determining the distance to an object using the echo transit time method can be evaluated and displayed in different ways. Besides, the height of the echo amplitude can be used for evaluation purposes.
In general, a distinction can be made between four operating modes of ultrasonic sensors.
In this type of sensor, the emitter and receiver are located in the same housing. This design simplifies installation and is well suited for fill level detection in tanks. The surface of the filling material reflects the emitted sound waves so that the sensor registers a limit level and continuously measures the level.
Not the object itself, but a background used as a reflector (such as a conveyor belt, machine part, or the floor) ensures a secure function of the retroreflective sensor. Regardless of whether they are small, big, angled, or sound-absorbing—all types of objects located between the sensor and the reference object are detected. Here too, the one-piece housing enables easy installation, wiring, and commissioning.
Thru-beam sensors operate with separate emitter and receiver transducers. If an object such as a bottle interrupts the sound beam, the sensor switching output is activated. Even sound-absorbing objects are securely detected. Another benefit of the thru-beam principle over the diffuse mode sensor is the doubled range. Additionally, the switching frequency of thru-beam sensors is considerably faster, paving the way for numerous fields of (high-speed) applications.
In addition to the previously described ultrasonic sensors, there are also double sheet sensors: instead of measuring transit times, they assess the amplitude attenuation the caused by the respective object (e.g., sheets of paper).