The parking sensor is of great assistance to the driver. When the parking sensor has an audible beep, the frequency of the beep will denote how close the vehicle is to an object. Should the beep be continuous it is an alert that the driver is too close and corrective action needs to be taken. Generally they are attached to the rear bumper of the vehicle.
When the alert is visual it is a read out on a screen, the intensity of which will denote the proximity of the object.
There are two types of parking sensors. One is electromagnetic and the other is ultrasonic. In an electromagnetic sensor an electromagnetic field is created behind the car. When the car approaches an obstacle, maybe another car, person, inanimate object or even the curb, the field gets disturbed. This type of parking sensor only alerts about an obstacle but cannot gauge the distance to it.
In an ultrasonic parking sensor the waves emitted are sound waves. The sound waves sound off the object and alert the sensor. The parking sensor sends or receives sound waves. A mini computer within the sensor box registers the waves emitted by the objects in the path of the vehicle. The strength of the signal will reflect how close the obstacle is.
The older models of the parking sensor which were electro magnetic had difficulty in functioning during bad weather. Due to this, the new parking sensor uses ultrasonic and wireless technology. These waves are of a very high frequency, short and are able to penetrate any medium. Because of the high frequency of the ultrasonic wave it cannot be picked up by the human ear the parking sensor box is equipped with an alert device. However these types of parking censors are considered cumbersome since many sensors have to be installed. It is the opinion of many that the older type of electromagnetic parking sensor is easier to install and maintain.
Even though the parking sensor is installed it would be sensible to use our own judgment and vision in parking because the parking sensor is dependent upon external factors such as weather and temperature and could always send a wrong signal