Investigating Problems with the Tesla HomeLink RF Signal with a HackRF and GNU Radio

Tesla vehicles have a feature where they can copy and mimic a garage door remote via a built in transmitter on the car itself. This frees you from having to carry around a garage door key fob, and you can simply open your garage door by pressing a button on the car's LCD screen.

However, some people have reportedly been having a little trouble with this feature as in some cases the garage door would begin opening, and then suddenly stop opening as if the keyfob button had been pressed twice.

Over on YouTube CWNE88 decided to investigate this problem using his HackRF and GNU Radio. From a simple waterfall he was able to determine that the Tesla actually transmits the mimic'd garage door signal for a full two seconds.

As a keypress from the original keyfob would typically result in a much shorter transmission, CWNE88 believes that the long two second transmission could in some cases be seen as two transmissions by the garage door, resulting in an open, and then close command being detected.