The Demodulate and Denoising of Vibration Signal under very Noise Condition

Abstract

For the failure diagnose of onsite mechanical equipment, which based on vibration noise in section, both characteristic signal and noise influence were contained in vibration signal, which all accepted by the machine. The problem arise when the characteristic signal was weak compare with the useless noise, the useful signal becomes hard to obtain, hence result in lower accuracy of the equipment. In this thesis, a new method based on the delayed autocorrelation demodulation method was analyzed and will be used on demodulation noise reduction: Based on the noise reduction feature of autocorrelation function, the related analysis was taken on vibration signal, then the autocorrelation function for the signal was obtained. Then with proper delay on autocorrelation function to avoid noise effect and envelop demodulation, we could achieve the demodulation result. The theoretical analysis and simulation experiments has proven the delayed autocorrelation demodulation method achieve better anti-noise performance than direct demodulation method, meanwhile, the delayed autocorrelation demodulation method could also highlights the characteristic information.