(WFRV) – We know police use radar to track the speeds of passing vehicles, but how does it work and how do they make sure the readings are accurate?

The Rock County Sheriff’s Office explained the process of using and confirming radar readings in a recent Facebook post.

The Sheriff’s Office says that all of its squad cars get equipped with certified speedometers right from the manufacturer.

The radar tracks the speed of a target vehicle and compares it to how fast the squad car is going. A deputy is then able to confirm the squad car’s speed with the certified speedometer.

The Sheriff’s Office also says that in order to be accurate, deputies test their radar internally and with tuning forks before and after each shift.

If the radar tests inaccurately, the deputy takes it out of service for repair.