Vibration response signals containing periodic components such as obtained from rotating equipment, gears, etc., can be effectively analyzed in the frequency domain. The averaging of spectra wherein the Fourier transform operation is synchronized with a particular periodic component, will reinforce that frequency component and all of its harmonics, while all nonsynchronous data will tend to be nonreinforced, thereby enhancing the synchronous spectral components. Features such as gear teeth and turbine blade passing frequencies, etc., and their related sidebands, can be extracted as signatures for baseline comparison and fault evaluation. This paper will discuss signatures obtained from averaged spectra and the related set of synchronous spectra; i.e., a synchronous average spectrum for each periodic component of interest.