Ultrasonic sensors operate using sound transmission. The frequency of the sound waves used are typically higher than 20kHz which is outside the range detectable by the human ear. The sound is transmitted and then reflected by the surface of the object and the distance is then calculated based on the time-of-flight of the sound reflection. The known speed of sound is 343m/s at 20°C which can be used to precisely measure the distance travelled by a pulsed signal from the ultrasonic emitter. The sound wave is not affected by dust or moisture in the atmosphere unlike optical distance measurement sensors. As the technology relies on a reflected signal, there must always be a distance for the emitted pulse to travel. The minimum distance for a typical ultrasonic sensor is 25mm; distances shorter than this are in the “blind zone”. The maximum distance can be several metres depending on the model chosen. The “beam” of ultrasonic sound can be focussed for a more precise location, avoiding false triggers from surrounding objects. Output can be analogue or digital with options of relay or transistor outputs at operator-set distances. Suitable applications: machine automation, object counters, vehicle positioning, silo / enclosed container grain or liquid level monitoring and more.
Ultrasonic Position Sensors
LINEAR OVERVIEW