Abstract: A 2-channel time-difference sampling method is proposed.It is a new method for determination of compressor blade vibration frequency.According to the correlation and the phase difference between the two sampled signals,and using interpolation and search,it can availably overcome the aliasing,which comes from the lower sampling frequency,and thus determine correctly the blade vibrative frequency.The method has been applied to blade vibration monitor system and achieves good results. It has advantages of being fast and simple,with high accuracy and wide frequency range.

Key words: blades-vibration measurement, frequency measurement, spectrum analysis