Define 'echo' in the context of radar speed measurement.

In the context of radar speed measurement, 'echo' refers to a reflected signal that returns from an object after the radar wave has been emitted. This phenomenon is crucial to how radar systems operate; the system measures the time it takes for the radar signal to travel to an object and back. The quality of the echo can significantly affect the accuracy of speed readings. If the echo signal comes from an unintended object—such as a car in the lane next to the target vehicle—it can lead to incorrect speed measurements. Therefore, understanding how echoes interact with radar technology is essential for law enforcement officers to ensure that they obtain accurate speed data when monitoring traffic. This makes recognizing and handling echoes vital in maintaining the reliability of speed enforcement efforts.