What type of radar speed detection error occurs from inaccurate alignment of the radar unit?

The type of radar speed detection error that arises from inaccurate alignment of the radar unit is known as cosine error. This error occurs when the radar beam is not perfectly aligned with the direction of the target vehicle's travel. When the radar unit is misaligned, it can lead to an underestimation or overestimation of the vehicle's speed because the radar measures the component of the vehicle's speed that is directly towards or away from the unit.

If the radar is aimed at an angle relative to the vehicle's direction, the speed reading will be affected by the cosine of that angle, hence the term "cosine error." For instance, if the target vehicle is moving at a certain speed but the radar unit is not aligned properly, the measurement will reflect a speed value that is less than the actual speed, making this a critical aspect for accurate speed enforcement. Proper alignment of the radar equipment is essential to mitigate this error and ensure that speed readings are accurate and reliable.