Ultrasonic Sonic Sensor

How it Works

The Ultrasonic Sensor is an electronic device that converts the ultrasonic sound wave into an electric signal. The HC SR04 sensor module consists of an ultrasonic transmitter, a receiver, and a control circuit. When it is triggered by a HIGH-LOW pulse at the ‘Trig’ pin, the transmitter emits a sonic burst of 8 pulses( 40 kHz ultrasonic frequency). These pulses when hit by an object, get reflected and received by the sensor(receiver). The control system process these pulses and sends them to the ‘Echo’ pin. Which further can be read by a microcontroller.

Ultrasonic Sensor ModuleHC-SR04
Ultrasonic Sensor Module HC-SR04


Steps for an Operation

Ultrasonic sensor timing diagram
Ultrasonic sensor timing diagram

Distance Caculations

Velocity of Ultrasonic Sound

Velocity of sound depends upon the environmental temperature, therefore can be calculated using Steinhart Equation-

Here- T is a temperature in deg centigrade. Let say the atmospheric temperature is 30 deg then the velocity of sound(ultrasonic) would be:-

Velocity of sound calculation

Now the distance of an object can be calculatedas:-

Range Calculation
Range Calculation 2

Applications of Ultrasonic Sensor

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