National Instruments Corporation
Machine Condition Monitoring Using Phase Adjusted Frequency Referenced Vector Averaging

Abstract:

System and method for machine condition monitoring using phase adjusted vector averaging. An analog signal from a sensor measuring a machine parameter may be acquired, thereby generating a first digital signal that includes multiple analysis blocks of data. For each analysis block, a complex valued frequency spectrum (CVFS) may be computed via a Discrete Fourier transform (DFT), at least one reference frequency may be specified, and a complex valued phase compensation vector that preserves magnitude while adjusting phase constructed to achieve coherence between reference frequency components (RFCs) and the selected analysis block. The CVFS may be phase compensated by multiplying the complex valued phase compensation vector with the complex-valued frequency spectrum. The complex valued frequency spectra of the analysis blocks may be vector averaged, thereby improving signal to noise ratio at specified frequencies. RFCs in the averaged spectrum may be identified, thereby generating average RFCs analyzable to determine machine condition.