According to the Idaho State Police, the troopers do not lock in the speed of a violator on the RADAR.  The trooper observes the speed of an approaching vehicle and by not locking in on the speed, they can determine if the speed is increasing or decreasing. The trooper uses visual observation and an audible sound emitted by the RADAR to determine which vehicle the RADAR is identifying.  Locking the RADAR increases the chance of the wrong vehicle being identified.  As a result, the trooper cannot show you the speed readout on the RADAR if you are stopped for speeding.

Idaho’s Office of Highway Operations and Safety endorses the use of laser radar units for Idaho’s law enforcement patrol officers.  The laser radar units contain a computer chip that can identify how fast the car is traveling and the distance between two cars.  An additional enhancement is that they can pick out one car in a group.

If you look up in the sky you might also see law enforcement.  A plane or helicopter can determine how fast a vehicle is going by how long it takes to travel on a specific stretch of highway.