A wave that is repetitive but not a sine wave results in what in the spectrum?

When a wave is repetitive but does not conform to a sine wave shape, it will generate a spectrum that contains harmonics. Harmonics are integer multiples of the fundamental frequency of the wave and are produced when the wave shape is not purely sinusoidal. For instance, square waves, triangular waves, and other non-sinusoidal waveforms all contain frequencies at multiples of the fundamental frequency they are based on, leading to the presence of these harmonics in their frequency spectrum.

This distinct characteristic of harmonic generation is a critical concept in vibration analysis, as the presence of harmonics can indicate specific issues in machinery, signal processing, and communications. The analysis of these harmonics helps in diagnosing problems, understanding system behavior, and modifying system designs for better performance.

In contrast, noise typically represents random, erratic signals without a clear repetitive structure, while sidebands refer to frequencies adjacent to a carrier frequency caused by modulations. Static denotes unchanging or constant signals without variations or periodic components. Thus, the correct term associated with a repetitive yet non-sinusoidal wave is indeed harmonics.