What is a significant factor that affects the accuracy of radar speed measurements?

The accuracy of radar speed measurements is significantly influenced by the angle at which the radar is aimed. When a radar unit is set up, the angle between the radar beam and the target vehicle can greatly affect the measurements. If the radar is not aimed directly at the vehicle, the speed that is recorded may not be accurate due to the cosine effect. This refers to the phenomenon where the measured speed decreases as the angle increases away from being directly in line with the target.

For radar technology to produce precise speed measurements, it is crucial for the radar beam to be aimed as closely as possible at a right angle to the direction of travel of the vehicle. If the angle is too steep, the speed readout may underestimate the actual speed. Hence, proper alignment of the radar unit is essential to ensure reliable readings.

Other factors such as vehicle color, length of the vehicle, or the presence of speed limit signs do not directly influence the measurement taken by a radar device. These factors may affect enforcement decisions or visibility, but they do not affect the radar's operational accuracy in terms of speed detection.