A Kalman-based phase-locked demodulation for Electromagnetic Acoustic Transducer

In order to achieve higher reliability of Electromagnetic Acoustic Transducer (EMAT) applications, a Kalman-based phase-locked demodulation technique is proposed to detect weak echo signals in this paper. The proposed demodulation algorithm utilizes Kalman filter as its low-pass filter (LPF) combined with the characteristics of the zero-crossing frequency of the average filter. The computational test is conducted to detect the weak signal of echoes in EMAT coils at different SNR, in which the proposed demodulation is compared with the one using the average filter as LPF. The comparison results show that the proposed demodulation method can detect the echo signal when SNR is below 0dB and, in terms of noise suppression, the proposed demodulation method performs better.

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