Passive Infrared Sensor:
A Passive Infrared Sensor (PIR sensor) is an electronic device that can detect motion by sensing changes in temperature. It measures infrared radiation emitted from the body heat of living beings and other warm objects. PIR sensors are commonly used in security systems, automatic lighting systems, and home automation systems. The PIR sensor consists of a pyroelectric sensor and a Fresnel lens that focuses the infrared energy onto the sensor.
When a warm object moves across the sensor's field of view, the infrared energy detected by the sensor changes, triggering the sensor to send a signal to the connected device. PIR sensors are ideal for detecting motion in indoor and outdoor environments and are highly reliable and cost-effective.
Ultrasonic Sensor:
An Ultrasonic Sensor is a device that uses sound waves to detect the distance of an object. It sends out high-frequency sound waves and measures the time taken for the waves to bounce back from the object. This technology is commonly used in robotics, automobiles, and industrial automation.
Ultrasonic sensors can detect objects at a distance of several meters, and their accuracy is not affected by the color or surface texture of the object. However, they can be affected by environmental factors such as wind, temperature, and humidity.
Ultrasonic sensors consist of a transmitter, receiver, and signal processing circuit. The transmitter emits ultrasonic waves, which bounce back from the object and are detected by the receiver. The signal processing circuit calculates the time taken for the waves to bounce back and determines the distance of the object from the sensor.
Overall, both PIR and Ultrasonic sensors are important technologies used in various applications to detect motion and distance.