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Ultrasonic Sensors
An ultrasonic sensor (also known as transceivers when they both send and receive) is a device that works in much the same was as RADAR and SONAR. Ultrasonic sensors are able to broadcast a powerful, ultrasonic frequency and then detect the ultrasonic sound waves as they bounce off of objects and return to the sensor. Ultrasonic sensors are almost always use for measuring speed or direction and are very efficient at determining its position.
How Ultrasonic Sensors Work
Ultrasonic sensors typically use a transducer which generates sound waves in the ultrasonic range, above 18,000 hertz, by turning electrical energy into sound, though dog whistles and several other devices can convert mechanical energy into an ultrasonic frequency, ultrasonic transducers are usually made from piezoelectric crystals that are able to change size when a voltage is applied to them. When an alternating current is applied to a piezoelectric crystal, it vibrates extremely fast and produces an ultrasonic sound wave. Then upon receiving the echo turn the sound waves into electrical energy which can be measured and displayed. The detector is also made of a piezoelectric crystal but is able to produce a voltage when an ultrasonic frequency comes in contact with it.
Applications
Ultrasonic sensors can be used in a wide variety of applications but typically involve
measuring speed, distance, or volume.
Used in navigation to detect where the device, as well as the user, is it.
Used to detect wind speed and direction as well as measure how much liquid is in a container
by measuring the distance from the top of the container to the surface of the liquid.
Used in humidifiers, burglar alarms, medical ultrasonography, sonar, non- destructive testing,
and some forms of testing.
Advantages
Able to produce ultrasonic frequencies that cannot be heard by humans, making them ideal
for quiet environments.
Do not use a lot of electricity.
Simple in design
Relatively inexpensive.
As some piezoelectric crystals can be used for both transmitting and receiving ultrasonic
sound waves.
Disadvantages
Ultrasonic sensors do not have many disadvantages but are limited in their capabilities. For example,
the readings from an ultrasonic sensor can be distorted by
Density,
Consistency,
Material.
For example foam on the surface of a fluid in a tank could distort a reading.
Ultrasonic sensors can be found as different housings as,
Cylindrical shape.
Cylindrical design allows for installation in various applications and Suitable for level and open channel flow measurement, obstacle avoidance, automation control, Robotics and proximity sensing. Construction is generally sealed for rugged use. This shape is common for board level and application mountable types. Housings are made of stainless steels or plastics for use in different application environments. Connectors are lids for board level and wires for rugged designs. Output generally needs separate signal conditioning board to use sensor as distance measurement or obstacle identifying mode.
Threaded Housings
Available for up to 40m measurement in slurry, powder, granular, and liquid level applications. Threaded housing makes it easy to mount in application environment. Rugged sealed housing designs generally accommodate transceiver and signal processing electronics.
Sensors with Sealed one piece housing.
These types of sealed one piece PVDF (Polyvinyl dense Fluoride) housings are used in chemically aggressive environments.
