Abstract:By utilizing the stochastic subspace identification, modal parameters were extracted from simulating vibration signals contaminated with specified levels of noise. With the modal parameters identified from the signal without noise being as the standard, the errors with the standard of modal parameters from signals polluted by various levels of noise were obtained. So the error, i.e. the modal parameter noise, was related to the noise level of signals. A reasonable procedure of simulating noise for modal parameters was put forward. The requirement of damage identification on the signal noise ratio was also studied based on simulations.