A basic ultrasonic distance sensor measures distance using sound waves through a process called "echo ranging." It consists of two main components: a transmitter and a receiver. Here's a step-by-step explanation of how the sensor works:
Transmitter sends ultrasonic waves: The sensor's transmitter emits a short burst of ultrasonic sound waves. These waves are inaudible to the human ear since they operate at a frequency above the audible range (typically around 40 kHz to 200 kHz).
Propagation of sound waves: The emitted ultrasonic waves travel through the air in the form of a sound wavefront.
Reflection from an object: When the sound wavefront encounters an object in its path, it gets partially reflected back towards the sensor.
Receiver detects the echo: The sensor's receiver, typically located close to the transmitter, picks up the reflected sound wave (echo) after it bounces back from the object.
Measuring time of flight: The sensor measures the time it took for the ultrasonic wave to travel from the transmitter, hit the object, and return back to the receiver. This time is commonly referred to as the "time of flight."
Distance calculation: Using the speed of sound in the medium (usually air) and the measured time of flight, the sensor can calculate the distance to the object. The formula for calculating distance is as follows:
Distance = (Speed of Sound × Time of Flight) / 2
The division by 2 is necessary because the sound wave travels the distance twice (to the object and back) during the measured time.
Output: The calculated distance is then output by the sensor, which can be in various forms depending on the sensor type, such as an analog voltage, digital signal, or through a serial interface.
By measuring the time it takes for the sound waves to travel and return, ultrasonic distance sensors can provide real-time distance measurements to nearby objects. These sensors are commonly used in robotics, automation, industrial applications, and even in consumer electronics like parking sensors in vehicles or proximity sensors in smartphones.