█ Introduction

By the ultrasonic sensor, control and display (or buzzer) and local composition, it can tell the driver his around obstacles by voice or a more intuitive display case. Relieve the driver stop, reverse and start to visit around the vehicle caused by problems, and to assist the driver to clean the line of sight angle and sight ambiguous death of the shortcomings of progressive drive insurance.

█ The principles of ultrasonic parking sensor

Measurement of pulse reflection time

Ultrasonic parking sensor works by ultrasonic pulse from the sensor (transducer) to issue, reflected by the surface acoustic wave sensor to receive the same after the conversion into electrical signals, then, through the time of transmitting and receiving sound waves to calculate the distance from the sensor to the measured object. When close to a safe distance when reversing, it can tell the driver his around obstacles by voice or a more intuitive display case.

The relationship between the distance up to the object. L and the reflecting time T is expressed by the following formula :

L=C • T/2

C is the velocity of sound; L is the measured distance; T is the time of transmitting and receiving sound waves

Principles of measuring distance.

                                                                                                                                  The example of pulse transmitting circuit