That is how they work. Hence the story of the driver stranded 300 miles from home because he dropped the device in his drive after starting the engine. But, interesting as this technical discussion is, it begs the question of why these devices are becoming so ubiquitous. Are drivers becoming so indolent that pressing the button the key is just far too much effort? __________________________________________ David C Brown 43 Bings Road Whaley Bridge High Peak Phone: 01663 733236 Derbyshire eMail: dcb.home@gmail.com SK23 7ND web: www.bings-knowle.co.uk/dcb *Sent from my etch-a-sketch* On 9 July 2018 at 17:06, Van Horn, David < david.vanhorn@backcountryaccess.com> wrote: > > So what would happen if you were driving legitimately and the keyfob > battery died? > I'd take exception to a sudden panic stop on the interstate. > > I suspect that once the vehicle is started, that they keep everything > going till the car is shut down again for exactly that reason. > > > > -----Original Message----- > From: piclist-bounces@mit.edu On Behalf Of > Timmothy Relerford > Sent: Monday, July 9, 2018 9:50 AM > To: Microcontroller discussion list - Public. > Subject: RE: [EE]:: Wrapping key-FOBs in tinfoil > > > If the key fob was inside someone's house and a thief used some method o= f > repeating the signal to start the car and drive away, what happens after > they get some distance away? > Does the car shut off? > In other words, doesn't that fob signal have to remain in proximity of > the car to keep it going? > After all, if you're the rightful owner, and you have the fob in your > pocket and you get into your car and drive away, no matter where you go, > that signal will be in proximity of the car. After all, you're sitting = in > the front seat. > But if the signal is being repeated, at some point, that signal will > disappear. Will the car turn off now? If it does, then the thief would > only get a short distance away before the car stops and he won't be able > to get it started again unless he copies the signal and programs a piece = of > electronic equipment to act as the fob from that point. I guess they > could strip it or tow it after that, but that would seem risky to me. > > > > Regards, > > Jim > > > -------- Original Message -------- > > Subject: Re: [EE]:: Wrapping key-FOBs in tinfoil > > From: Denny Esterline > > Date: Mon, July 09, 2018 10:25 am > > To: "Microcontroller discussion list - Public." > > > > > > > > > > > > > It seems to me the only way the key fob is going to be able to be > > > copied is if someone presses one of the buttons to transmit the > > > signal. If it is just sitting on a table or hanging on a wall hook, > > > how would someone outside the home (or bldg.) cause the key fob to > > > transmit? > > > > > > > > > > This is a misunderstanding. I cannot claim to know the underlying > > technology, but many new car keyfobs today are "proximity devices". > > Fob in pocket, press button on dash to start car. Definitely do not > > have to press any buttons on the fob. > > > > I've not read Russell's linked article, but I did recently read an > > article claiming thieves were using SDR as a repeater to significantly > > boost the range of what the car considers "proximity". The claim was > > with your keys on a hook by your front door, they could use a repeater > > outside and drive the car away. > > > > The really fun trick here is they make no effort to capture or crack > > any codes, just boost a signal. > > > > > > -Denny > > -- > > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > > View/change your membership options at > > http://mailman.mit.edu/mailman/listinfo/piclist > > -- > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > View/change your membership options at http://mailman.mit.edu/ > mailman/listinfo/piclist > > -- > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .