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My key

Posted: Tue Jan 14, 2020 8:47 am
by trangtrainam
Hi all,

As per the title i want to search my home for a lost Mercedes car key....

Did you know that MB in Australia want to charge $1275 + labour for a new key!!! What a ripoff!

Ive been aware of RTL SDR for a few years, but never really had an application to get into it with..but i have quite an incentive now. My car has keyless entry/ingition so i imagine the keys have some sort of beacon transmission to tell teh car they are close by.

I was hoping i can use a RTL-SDR to sniff for this beacon and thus try to find the missing key in my home...

Is this possible? I really dont want to spend $1200 to replace the key as as soon as i do the missing one will be found!

Re: My key

Posted: Tue Jan 14, 2020 7:17 pm
by aurgathor
Is that a so called "transponder key"?
Transponder keys do not have a battery; it is an embedded chip which is powered by the radio signals itself that are sent by the car. The radio signals are of a very low strength that they activate the chip only when the key is very near to the dashboard or when it is pushed into the ignition to start the car.
You need to send out the correct signal to make them transmit back something, and I'm afraid the usual TX capable SDRs themselves are probably too low power for that, so you also need an amplifier.