Time-frequency plane Wiener filtering of the high-resolution ECG: background and time-frequency representations.
This paper introduces the concept of a posteriori Wiener filtering (APWF), performed in the time-frequency plane. The objective is to improve the signal-to-noise ratio (SNR) of the ensemble-averaged high-resolution electrocardiogram (HRECG). APWF was developed to address the problem of a limited ensemble size for estimating ensemble-averaged evoked potentials. For the HRECG, we identify the major challenge as adapting the time-frequency structure of the filter to that of low-level cardiac signals. Technical limitations and the characteristics of HRECG signals make time-frequency analysis of the ensemble average problematic. Normal and abnormal signal components are difficult to distinguish due to low time-frequency energy concentration and limited spectrotemporal resolution. However, considering the entire ensemble of repetitive ECG records, signal and noise components are separable in the time-frequency plane. This forms the basis of the new time-frequency plane Wiener (TFPW) filter, applicable to any ensemble averaging problem involving repetitive deterministic signals mixed with uncorrelated noise.
Lander
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P
Department of Veterans Affairs Medical Center, Oklahoma City 73104, USA. paul@paul.vahsc.uokhsc.edu
Berbari
E J
EJ
D004562:Electrocardiography; D005071:Evoked Potentials; D005583:Fourier Analysis; D006801:Humans; D012189:Retrospective Studies; D012815:Signal Processing, Computer-Assisted; D017180:Tachycardia, Ventricular / Q000175:diagnosis; D013997:Time Factors