412 CH ULTRASONIC MODULE GH-311………The ultrasonic sensor works on the principle of SONAR and RADAR system which is used to determine the distance to an object.
An ultrasonic sensor generates the high-frequency sound (ultrasound) waves. When this ultrasound hits the object, it reflects as echo which is sensed by the receiver
By measuring the time required for the echo to reach to the receiver, we can calculate the distance. This is the basic working principle of Ultrasonic module to measure distance.