Directional wavelet transform in the context of complex quadrature Doppler signals
Nizamettin Aydın, H.S. Markus · IEEE Signal Processing Letters · 2000
Most Doppler ultrasound systems employ quadrature demodulation techniques at the detection stage. The information concerning flow direction encoded in the phase relationship between in-phase and quadrature phase channels is not obvious at this stage. A method based on the utilization of complex wavelets and negative scales has been described. It eliminates the intermediate processing stages by mapping directional information in the scale domain.