XPost: alt.home.repair, sci.electronics.design   
   From: devap@deepcore.eu   
      
   On 2022-12-28 Sergey Kubushyn wrote:   
   > Please, don't spread that BS about no signal unless a keyfob button is   
   > pressed. It is simply false.   
      
   I have to chime in... as with everything technical or electronic, people   
   have to know how these things work. With more knowledge they become less   
   scary.   
      
   All keyless cars emitt a weak radio signal that shouldn't extend over   
   5-10 meters around the car. The idea is to 'trigger' the keyfob in your   
   pocket as you approach your car.   
      
   Once your keyfob picks up the signal from the car, it sends back its own   
   signal. This is how the 'greeting function' is realised.   
   When you grab the door handle, the car senses it and sends a radio   
   signal to the keyfob, which responds then. If the exchanged codes match,   
   the car unlocks the door. Same happens when you press the START button.   
      
   On some keyfobs, you can see a small LED light up when it responds the   
   car's signal.   
      
   The thieves abuse this systems be having a receiver next to your car and   
   grabbing the door hanlde. This receiver picks up the signal of the car   
   and relays it to a second device with has to be near your keyfob. This   
   second device sends the relayed signal to your keyfob, which responds,   
   thinking it heard the car's signal. And this answer gets relayed back to   
   the first device near the car... and the car thinks, it got the answer   
   from the keyfob ...   
      
   In essence, it is a design flaw (bug), becaus nobody thought about these   
   relaying schemes ...   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)