AFAIK in Europe they have full-encryption. But the presence of encrypted traffic in the reserved airwaves near you means there are cops/fire/ambulance nearby. I remember reading about someone building a cop radar by exploiting this property!
There are false positives (e.g. you're speeding down the autobahn, and there's an ambulance in a town you're passing through), but it's probably good enough...
There are false positives (e.g. you're speeding down the autobahn, and there's an ambulance in a town you're passing through), but it's probably good enough...