My car comes with a touch access system - with the key in my pocket, I need only touch a specific spot on the driver's door handle to lock the car. One day, I did the same drill after a drive, but the car did not lock, then I realised the key had dropped from my pocket onto the seat. How did the touch access system know not to lock me out of my car?
The latest electronic keys that many car manufacturers use are no longer of the type that relies on infrared (IR) signals. Home audio and video remote units still use the IR system but, with cars, the current technology uses radio signals and the key functions as both receiver and transmitter.