Ohhhh, it's a lot more than that.
You're being tracked by your car and phone bluetooth MAC addresses. That's how the "X minutes to exit Y" signboards work. They time how long it takes to see a particular MAC address appear at the next receiver.
You're being tracked by your car and phone bluetooth MAC addresses. That's how the "X minutes to exit Y" signboards work. They time how long it takes to see a particular MAC address appear at the next receiver.
What does this mean? Are they just measuring radio power levels in the 2.4GHz spectrum, and using that to determine whether a car is there or not? Or are they actually somehow capturing bluetooth signals, decoding them, and extracting identifiers (eg. MAC) from them?