Noise removal in ECG signals using the quadratic filter

This article studies the capability of applying the quadratic filter (QF) for removing noise in ECG R-peak detection preprocessing. The important advantage of the QF, which is a 2D filter, over linear filtering is that it has two degrees of freedom for optimizing noise removal in ECG signals. The QF is designed in the frequency domain based on the sum of two 2D Gaussian filters. Subsequently, the filter coefficients can be obtained using the inverse Fourier transform. The QF from proposed algorithm was evaluated with ECG signals from the MIT-BIH arrhythmia database (MITDB). Results show that the QF provides the SNR value better than that from the conventional linear filtering 20 dB in ECG noise removal. This opens the opportunity for the QF as a preprocessing step to increase accuracy in ECG R-peak detection.