| Ultrasonic sensors are small devices used to detect | | | | the type of sensor used. Advanced ultrasonic |
| the presence of intruders and other foreign objects. | | | | proximity sensors used for spy surveillance generate |
| These can discreetly be placed in courtyards and | | | | a highly focused beam of ultrasonic sound that can |
| inside homes to detect the presence of moving | | | | easily access tight spaces and openings ranging from |
| objects alien to the surroundings. They operate at | | | | .5 inch to four inches long in diameter. |
| frequencies in the range of twenty-five to forty | | | | Some of these devices are equipped with external |
| kilohertz, which is way above the human hearing | | | | touch function that allows the user to remotely |
| range. | | | | program the best scanning range for the application. |
| The basic mechanism used in ultrasonic sensors | | | | They may also have device-locking features that |
| activates a quartz crystal that emits ultrasonic sound | | | | prevent unwanted output programming changes. |
| waves in the surrounding areas. The detector system | | | | Apart from detecting human movement, they also |
| senses the frequency of reflected waves to detect | | | | have the capability to detect any material that can |
| any slight changes that might occur due to a moving | | | | bounce back sound such as liquids and clear |
| object technically known as the Doppler effect. | | | | substrates like plastic and glass. |
| These devices are designed to produce ultrasonic | | | | Ultrasonic sensors are also used in different industrial |
| sound waves in a continuous fashion without any | | | | sectors such as pharmaceutical, medical, food, |
| blind spots or gaps in the coverage pattern. This | | | | cosmetic, and household & personal care |
| makes it possible to detect small gestures such as | | | | manufacturing. They have enabled the detection of |
| hand motion, which can be detected at a distance of | | | | minor flaws in products during the production |
| twenty-five feet, arm and body movement at thirty | | | | process, which if left unchecked can damage the |
| feet, and full body motion at forty feet depending on | | | | brand value of a product or company. |