Which term refers to a multiple of a radar signal that can affect speed readings?

The term that refers to a multiple of a radar signal affecting speed readings is "harmonic." In the context of radar technology, harmonics are integer multiples of a fundamental frequency. When a radar signal transmits, it can create harmonic frequencies in addition to the original frequency. These harmonics can interfere with the radar's ability to accurately measure speed by introducing additional components that can affect the signal's clarity and fidelity.

Understanding harmonics is crucial in speed measurement because they can lead to erroneous readings if they distort the primary signal the radar uses to determine the speed of a moving object. Radar devices are designed to minimize the impact of harmonics, ensuring that speed measurements remain as accurate as possible.

The other terms mentioned relate to different aspects of radar operation or wave phenomena. Reflective signals involve how radar waves bounce off objects, the Doppler effect refers to changes in frequency due to relative motion, and interference waves pertain to the combination of waves, which can also impact signals but do not specifically denote multiples of a radar signal like harmonics do.