Parking Sensors Explained: How to Get the Best Accuracy

Initially, car parking sensors were considered useful but not necessary functions. However, they turned out to be so convenient that in 2024, one can not imagine the best commuter auto without parking radars as standard. They are also available and widespread as additional equipment. The Indianapolis car dealership experts from Indy Auto Man explain how parking sensors work and what features to focus on when choosing.

Principle of operation

There are two device options, and each has its advantages and disadvantages.

Ultrasonic. This system uses special sensors and a control unit. The principle of operation is simple: the sensor is located in the bumper and sends ultrasonic waves. If they encounter obstacles, they are reflected and returned to the sensor. The distance to the obstacle is calculated based on the time of their return.

Ultrasonic parking sensors are simple and reliable but require installation in the bumper (there is also an option with suspended sensors). Another drawback of such devices is false alarms, for example, due to snow or ice adhering to the bumper.

Electromagnetic. The operating principle of such parking sensors is based on a change in the electromagnetic field when objects enter it. About the same is used in metal detectors. Electromagnetic parking sensors are a combination of a controller and a tape antenna. The antenna detects changes in the electromagnetic field, and the controller calculates the distance to the obstacle.

This type of parking sensor is good because it has no dead spots and does not require drilling holes in the bumper. The disadvantages are the inability to work with a non-removable towbar and periodic false alarms. In addition, since there is only one antenna, you will not be able to understand where the obstacle arose – to the right, left, or center. This is why electromagnetic parking sensors are not very common.
Location
Parking sensors can be installed in both the rear and front bumpers. In the rear, sensors are a great help even for experienced drivers, which is why they are most often placed there. But for beginners, controlling the distance to obstacles in front is also indispensable.

Number of sensors

• The effectiveness of ultrasonic models directly depends on the number of sensors.
• Two sensors per bumper are not enough. They can only be helpful for those who are going to buy a truck. Two sensors are enough to move it close to the loading ramp in a warehouse. This combination is rarely used for passenger cars.
• Four sensors can be called the optimal number for most models. They provide a good “view” and do not miss even small parking bollards.
• Six sensors are installed on large vehicles – for example, vans. When you need to equip a wide bumper with emitters, you can’t spread them too far apart. So, four sensors are installed in the rear and two more in the front.

Notification method

Another crucial aspect in the design of parking sensors is notification of the distance to an obstacle. There are several options.

• Sound. The simplest option is judging the distance by the frequency of the intermittent sound signal. The shorter the pause, the closer the obstacle. If the signal becomes constant, the distance is critical.
• Indicator. This option is most often used: on a small display, there are two lines of LEDs (for the right and left parts of the car). They light up as you approach an obstacle, starting with the outermost one. When everything is on fire, it’s time to stop.
• Digital. These parking sensors have an LCD screen that displays the distance to the obstacle. There is no particular point in this – the indicated distance will still not be 100% accurate, but you can approximately control it using indicators. Moreover, they work more reliably in low-temperature conditions.

Typically, visual notification methods work in conjunction with sound, but in some models, the alert can be turned off (for example, if you have a small child who regularly falls asleep in the car). Information from built-in parking sensors is often shown on the displays of on-board systems.

Parking sensors or rearview camera: which is better?

Those who want to make parking as safe as possible are often interested in whether parking sensors or a rearview camera is better. The question is not very correct.
Ultrasonic sensors detect any obstacles (provided they are installed correctly on the bumper). The main thing is that the sensors are not covered with snow or ice. The inability to work with distances less than 15 inches is the main shortcoming of such a device. If you need to park in a garage, the length of which is only 5 inches longer than the size of the car, the parking sensors will not help.
A rearview camera is preferable in this case. But from it, you only get an image, so you have to look at the screen. And you will also need to detect the obstacle yourself – the buzzer will not inform you of its presence. And the picture from the camera, especially at night, can be uninformative. In addition, if the lens is dirty, the camera will be useless.

Two devices allow you to summarize their advantages, although, models with both will cost more. In this regard, buyers of used cars benefit the most – the previous owner has most likely already equipped the auto with all the necessary systems, and they have practically no effect on the vehicle’s value on the secondary market.