The process of getting in and starting our cars we take for granted but this has certainly evolved over the years. For many years, getting into your car and starting it was a simple process that involved physically inserting a key into the keyhole on the driver’s door, opening the door and then turning the key in another slot inside to begin the engine ignition.
The modernisation of central locking then happened, which allowed driver and passenger doors to be locked and unlocked simultaneously. This then evolved into keyless entry, enabling drivers to lock and unlock their car from a distance by pushing a button on a key fob. In more recent years, car manufacturers introduced the next innovation of proximity sensing keys which have since risen in popularity.
When were proximity-sensing keys first introduced?
Proximity-sensing keys were first introduced on the Mercedes S-Class in 1998 and today are common on even affordable vehicles. You can select your vehicle make from our list by clicking here. The main benefit of proximity-sensing keys is they allow you to enter and start the car without having to actually have the key in your hand and unlock the car. Meaning, as long as the key is on your person (ie. In your pocket or bag), the driver can simply push a button or touch the door handle to unlock and subsequently turn on the car. Very beneficial if for example your hands are full or the weather takes a turn for the worse and you need to get into your car quickly!
How do proximity-sensing keys work?
Proximity-sensing keys operate through the transmission of radio waves. Cars equipped with this system have radio antennae located within the door handles that can transmit information on both ultra-high (around 300-400 MHz) and low frequencies (around 125 kHz). They key fob also has a similar antenna.
When the driver touches a button on the door handle to unlock the car, the system transmits a signal on a UHF frequency to determine whether there is an authorised unique transmitter (ie. key fob) nearby, the key fob will then respond with its own signal.
Additionally, the antennae within the car transmit a low-frequency signal that helps determine the key fob’s precise position and whether it’s inside or outside the car. If the key fob is close enough on the outside, the doors are unlocked, and if the fob is inside the car, the engine ignition will commence when the driver pushes the start button. In this way, at no stage in the unlocking or vehicle start-up process do you need to interact with the key fob itself.