Vibration Parameters Estimation using mHDFT Filter in PLL Technique

A closed loop modulated Hopping Discrete Fourier Transform (mHDFT) based quadrature detector is proposed to estimate the various vibration parameters. The modulated hopping DFT is efficient way of calculating DFT of N samples. The system poles always reside on the unit circle and as there is no twiddle factor involved in feedback of the filter so there is no accumulation of error while calculating the DFT of N samples. This algorithm is implemented in Phase Locked Loop design for non contact type vibration estimation. The detection accuracy of the proposed estimator is very high even for low frequency signals.