modern radars feed the doppler to the cop as a audio tone, steady tone, they sleep through it and let you pass, but if they hear that short down doppler, it wakes em up and you get a ticket. Lesson learned the hard way on a 55 in a 35 zone in the city, the cop said, if I would not have slammed the brakes as I passed, he would not have woke up.
In Ohio they dont notice you till your 6-7 over the limit on divided highways, but the mobile speed cams are 200$ plus administrative fee in Akron and Cleveland, and they get away with it because it is 0 points on the license, and thus a civil fee and not a ticket. (ba $tards used a loophole, even our local cops opposed it)
Steve