What Are Sidebands in Vibration Analysis?

Amplitude modulation is a non-linear process, and gives rise to new frequency components in the spectrum which would not be there without the modulation. These new spectral components are called sidebands. Amplitude modulation occurs often in vibration signals generated by rotating machines.

What are sidebands of an AM wave?

In radio communications, a sideband is a band of frequencies higher than or lower than the carrier frequency, that are the result of the modulation process. The sidebands carry the information transmitted by the radio signal. The sidebands comprise all the spectral components of the modulated signal except the carrier.

Why are sidebands produced?

When the signal is modulated onto the carrier in the electromagnetic spectrum, that signal occupies the small portion of the spectrum surrounding the carrier frequency. It also cause sidebands to be generated at frequencies above and below the carrier frequency.