Ultrasonic Linear Position Sensors and Switches

Ultrasonic linear position sensors and switches use ultrasonic waves in combination with light and frequency readings. Specifically, ultrasonic linear position sensors and switches use surface acoustic waves (SAW) and Lamb waves that reflect off the target. The distance between the ultrasonic linear position sensor and the target is calculated from the signal's return time and the propagation velocity of the measurement medium. Ultrasonic linear position sensors and switches are useful in environments that cause other sensing technologies to fail, such as dust, particle-laden air, moisture or wetness, or particularly arid conditions. When separated from their targets by a substantial distance, ultrasonic linear position sensors and switches are more accurate than other types of sensors.

Unlike other types of position sensors, ultrasonic linear position sensors and switches are not affected by color or material type. Instead, ultrasonic linear position sensors and switches only need an object to pass within their operating zone to bounce a signal. An oscillating cycle may be formed, including a feedback loop which includes an acoustical oath, electrical elements, and optical elements. The feedback loop of ultrasonic linear position sensors and switches produces an output frequency that is determined by a frequency measurement of the desired distances or angles.

Important specifications for ultrasonic linear position sensors and switches are the distance to be measured, the output signal desired, range resolution, and the sample rate.  The electrical output signal can be analog current or frequency, digital, or a computer signal that describes the position of the object being sensed. Analog current outputs for ultrasonic linear position sensors and switches are useful when transmitting a signal long distances. Feedback from an analog current is used to provide the appropriate current regardless of noise, impedance, etc. Analog frequency or modulated frequency outputs are a variation of the analog current output. In analog frequency outputs the signal is encoded via an amplitude modulation (AM), frequency modulation (FM), or additional modulations. The accuracy of ultrasonic linear position sensors and switches is measured as a percentage of the full scale. The sample rate is measured in hertz (Hz). Ceramic and electrostatic sensing elements are common technologies for ultrasonic linear position sensors and switches.

• Position Sensors and Position-Sensing Instruments
  Position sensors include wide range of sensors, switches and technologies that are used to determine the placement, speed or movement, direction, and location of a given target. Linear position...
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