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I have a question regarding the working of police radar detectors. Specifically, how exactly do they work? I understand how they could be used to determine a vehicle's distance, and thus to determine relative speed, but how, for instance, is it used successfully at an angle, especially when the angle is not known. Or, for that matter, from a perpendicular perspective.

Police radar measures relative speeds not distance (unlike regular radars which usually measure distance and direction). If the police car is moving, its speed is taken into account. I believe they are only used to measure approaching and receding speeds (they cannot take into account angles other than 0 or 180 degrees)

John Hawley

Well, if they measured from an angle different from 180 degrees they would get a smaller number for the speed, so if that was still over the speed limit, your real speed must have been way over the limit.

Arthur Smith

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