Ultrasonic Sensors
Ultrasonic sensors are small devices wont to detect the presence of intruders and other foreign objects. These can discreetly be placed in courtyards and inside homes to detect the presence of moving objects alien to the environment . They operate at frequencies within the range of twenty-five to forty kilohertz, which is much above the human hearing range. The basic mechanism utilized in ultrasonic sensors activates a quartz that emits ultrasonic sound waves within the surrounding areas. The detector system senses the frequency of reflected waves to detect any slight changes which may occur thanks to a moving object technically referred to as the Doppler effect . These devices are designed to supply ultrasonic sound waves during a continuous fashion with none blind spots or gaps within the coverage pattern. This makes it possible to detect small gestures like hand motion, which may be detected at a distance of twenty-five feet, arm and body movement at thirty feet, and full body motio...