North Carolina RADAR State Practice Exam

The term that describes the change in frequency of a radio signal when it reflects off a moving target is known as Doppler Shift. This phenomenon occurs due to the relative motion between the source of the signal and the observer (or the object reflecting the signal). When the object is moving toward the signal source, the frequency of the reflected signal increases, resulting in a higher pitch, while if the object moves away, the frequency decreases, leading to a lower pitch. This effect is crucial in various applications, including radar systems that detect the speed of vehicles or other moving objects by measuring the changes in frequency of the returned signals.

The other terms do not accurately describe this specific phenomenon. Echo Shift is not a recognized term in the context of frequency change due to motion, Frequency Modulation refers to a method of varying the frequency of a carrier signal, and Signal Deviation is generally related to the variance in signal levels but does not specifically pertain to the frequency change experienced in the Doppler effect.