The synchronous time averaging is an average technique that rejects the vibrations frequencies which aren’t in phase with the excitation ones. STA is mainly used with rotating machinery with 2 applications.
1 -Get the machine structural background spectra without stopping it. The FFT blocks are triggered by the hammer impacts which excites the structure. The time domain averaging amplifies the synchronous structure response and reject the machinery operation signals. The FRF shows the main resonances of the structure.
- 2 – Reject signal from other machineries sources in a workshop. In this case the Synchronous order analysis is used to keep the same order whatever the rotation speed. The SOA angle domain blocks are triggered synchronously with the main shaft pulse (or Key phasor). The angular domain averaging amplifies the vibrations from the machine operation while it reject the ones from other sources (structural resonances, other machines, etc…). This provide cleaned order spectra of the machine. NB it works also with FFT in time domain.