What type of detectors include ultrasonic, microwave, and photoelectric varieties?

Active sensors are designed to emit energy in order to detect the presence or changes in the environment, which distinguishes them from passive sensors that rely solely on energy coming from external sources. Ultrasonic, microwave, and photoelectric detectors exemplify active sensors because they generate signals and analyze responses to gauge the presence of objects or movement.

For instance, ultrasonic detectors send out sound waves and measure the time it takes for those waves to reflect back, allowing them to detect movement. Microwave sensors operate similarly by emitting microwave signals and detecting changes in their reflection. Photoelectric detectors use light beams and detect interruptions in these beams to sense movement or presence.

This active approach enables more precise detection capabilities in various environments, making these detectors effective for security and intrusion detection applications.