What determines how much higher or lower the reflected signal will be in relation to relative motion?

The amount by which a reflected signal is shifted due to relative motion is primarily determined by speed. This concept is rooted in the Doppler effect, which describes how the frequency of waves changes in relation to an observer moving relative to the wave source.

When the source of the signal and the receiver are in motion toward or away from each other, the frequency of the reflected signal is altered. If the relative motion is toward each other, the frequency increases, resulting in a "higher" reflected signal. Conversely, if they are moving apart, the frequency decreases, leading to a "lower" reflected signal.

Therefore, speed is crucial in affecting the amount of frequency shift and, consequently, how much higher or lower the reflected signal will be in relation to the object in motion. This understanding is fundamental when interpreting data from radar and lidar systems, as accurate readings depend heavily on calculations involving the relative speeds of the observer and the target.