title: Noise reduction in directional signals using multiple morse wavelets illustrated on quadrature Doppler ultrasound.
abstract: The use of multiple complex-valued Morse wavelets for the scalogram study of signals which are unidirectional at any time, but are bidirectional overall is considered. These wavelets are well-suited to identifying the forward and reverse components. Scalogram averaging which is possible due to the multiplicity of the complex-valued wavelets leads to a scalogram with reduced noise. Information from positive and negative scales can then be used to estimate a final "cleaned" scalogram. Quadrature Doppler ultrasound blood flow in the femoral artery is taken as an example to clearly illustrate the noise reduction.
authors.affiliation: Department of Mathematics, Imperial College of Science, Technology and Medicine, London SW7 2BZ, U.K.
authors.forename: Sofia C
authors.initials: SC
authors.lastname: Olhede
authors.forename: Andrew T
authors.initials: AT
authors.lastname: Walden
mesh_terms: D001783:Blood Flow Velocity; D003198:Computer Simulation; D015150:Echocardiography, Doppler / Q000379:methods*; D005263:Femoral Artery / Q000000981:diagnostic imaging* / Q000502:physiology*; D006801:Humans; D008955:Models, Cardiovascular; D011786:Quality Control; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted; D013269:Stochastic Processes