I have a passport too and the shit works pretty good.
However, I noticed cops (at least around here) have this little trick that when traffic is low, they will turn their radar on & off as cars pass by so that that your radar will not go off until you are already in the guns zone.
I got a ticket in the middle of the night one night, not a car on the road and all of a sudden my passport goes full signal strength. I hit the fucking breaks and when the cop pulls me over hes like "I know you have a radar dectector son, because as soon as I gunned you, you slowed down. I wasn't gonna give you a ticket, but I hate radar detectors, so now your screwed" smh