Zoom envelope method based on the real modulation and its application in the fault diagnosis

In order to solve the less fault frequencies and unsymmetrical sideband problem in the usual modulation signal of zoom spectrum, according to the principle of modulation frequency shift keying, advance real modulation frequency shift keying algorithm which can realize frequency range and frequency spectrum symmetry. After filtering and re-sampling the real modulation result, making use of the Hilbert transform to acquire the envelope technique, directly get the signal envelope spectrum, which is the actual Zoom envelope spectrum. Analyze zoom envelope spectrum by computer simulation in the paper and apply to the motor broken bar fault diagnosis, the result shows that it is easier for modulated fault characteristic frequencies to identify and measure in virtue of eliminating the effect of the useless modulated frequency, and overcome the disadvantages of usual zoom spectrum in fault diagnosis applications.