Radar involves sending out radio waves and listening to how their frequency changes when they strike an object, such as a vehicle. This is an
effective speed tracking device because the speed of the vehicle or other object affects the change in frequency. By contrast, laser detection measures the speed of a vehicle by sending out laser light and measuring the distance from the laser gun to the vehicle over time. The change in the distance provides a way to calculate the speed of the vehicle. When a police officer holds a gun toward a vehicle’s license plate, they must make sure to hold it steady to get an accurate reading.