North Carolina RADAR State Practice Exam

What can cause patrol speed measurements to appear lower than the actual speed?

1. Incorrect calibration of the RADAR unit

2. Moving angular effect caused by the RADAR's angle

3. Weather conditions like rain or snow

4. The speed of the patrol car

The correct answer is: Moving angular effect caused by the RADAR's angle

The moving angular effect can indeed cause patrol speed measurements to appear lower than the actual speed. This phenomenon occurs when the RADAR unit is positioned at an angle relative to the target vehicle's direction of travel. If the RADAR is not aligned directly with the path of the vehicle, the speed readings can be distorted. The further the angle from the direct line of sight, the more pronounced the underestimation of speed will be. This is due to the geometry involved in calculating speed based on the RADAR's return signal. By contrast, while incorrect calibration of the RADAR unit (the first option) can also lead to inaccurate readings, it would not necessarily cause consistently lower measurements; errors could be either higher or lower. Weather conditions (the third option) might impact the effective range or clarity of the RADAR signals, but they do not create a standardized bias in measurement. Finally, the speed of the patrol car (the fourth option) represents a different consideration; it does not directly affect the RADAR's ability to measure the speed of other vehicles accurately, though it does play a role in determining the relative speed between the patrol vehicle and the target. Understanding the moving angular effect is crucial for law enforcement officers utilizing RADAR technology, as