North Carolina RADAR State Practice Exam

What happens to the target speed reading when the RADAR correctly computes the target speed and the patrol vehicle speed changes?

1. The target speed reading remains unaffected

2. The target speed reading fluctuates with vehicle speed

3. The target speed reading increases by 2 mph

4. The target speed reading decreases by 2 mph

The correct answer is: The target speed reading remains unaffected

The target speed reading remains unaffected when the RADAR correctly computes the target speed, regardless of changes to the patrol vehicle's speed. This is due to the principle of radar operation, where the RADAR system measures the speed of a target relative to the radar unit itself. When the target's speed is accurately detected, it is displayed as the target speed, and any changes in the patrol vehicle's speed do not alter this reading. For example, if the radar is calibrated correctly and initially measures a target speeding at 60 mph, and then the patrol vehicle accelerates or decelerates, the target speed would still reflect the target's speed of 60 mph, not influenced by the patrol vehicle's movement. In essence, the RADAR's calculation is independent of the radar unit's own speed as long as it is properly calibrated and functioning to measure the target vehicle’s speed accurately.