title: Analysis of embolic signals with directional dual tree rational dilation wavelet transform.
abstract: The dyadic discrete wavelet transform (dyadic-DWT), which is based on fixed integer sampling factor, has been used before for processing piecewise smooth biomedical signals. However, the dyadic-DWT has poor frequency resolution due to the low-oscillatory nature of its wavelet bases and therefore, it is less effective in processing embolic signals (ESs). To process ESs more effectively, a wavelet transform having better frequency resolution than the dyadic-DWT is needed. Therefore, in this study two ESs, containing micro-emboli and artifact waveforms, are analyzed with the Directional Dual Tree Rational-Dilation Wavelet Transform (DDT-RADWT). The DDT-RADWT, which can be directly applied to quadrature signals, is based on rational dilation factors and has adjustable frequency resolution. The analyses are done for both low and high Q-factors. It is proved that, when high Q-factor filters are employed in the DDT-RADWT, clearer representations of ESs can be attained in decomposed sub-bands and artifacts can be successfully separated.
authors.forename: Gorkem
authors.initials: G
authors.lastname: Serbes
authors.forename: Nizamettin
authors.initials: N
authors.lastname: Aydin
mesh_terms: D000465:Algorithms; D016477:Artifacts; D004617:Embolism / Q000000981:diagnostic imaging*; D006801:Humans; D012815:Signal Processing, Computer-Assisted; D018608:Ultrasonography, Doppler / Q000379:methods*; D058067:Wavelet Analysis