There is no key as such. The fob for my Hyundai never leaves my pocket. Just by standing next to the car, the unlock button on the door is enabled. So if I walk up and push the button, it unlocks. If I'm not around, the button does nothing.
So there's no discernible event from the fob, as far as I can see. It's just a "this is me" signal.
I guess the Hyundais I've driven were different, in that the unlock button was on the fob rather than on the car door. Could you say, if you have multiple cars, does the fob work with all of them? I doubt that's the case, so I don't see why your "this is me" signal couldn't actually be a "this is me, fob 123ABC..., and I can authenticate with the vehicle with VIN# 123abc...".
your "this is me" signal couldn't actually be a "this is me, fob 123ABC..., and I can authenticate with the vehicle with VIN# 123abc..."
You're right, that might be it.
the unlock button was on the fob rather than on the car door
Let me clarify: the fob does have buttons for lock, unlock, panic, and open trunk. But I don't normally use them. My normal usage is as I described: just walk up with the fob in my pocket, and press the button on the door handle.
So there's no discernible event from the fob, as far as I can see. It's just a "this is me" signal.