What type of system uses inaudible sound waves to detect intruders?

An ultrasonic motion detection system uses inaudible sound waves, typically at frequencies higher than what humans can hear, to detect movement within an area. This system works by emitting ultrasonic waves and monitoring the reflections of those waves. When a person or object interrupts the path of these waves, the system detects a change in the received sound pattern, indicating the presence of an intruder.

This approach to intrusion detection is effective in various settings, as it can cover larger areas and is less susceptible to false alarms compared to other detection methods. Ultrasonic systems are often used in combination with other types of sensors to enhance security measures, making them a versatile choice in the realm of security technology.