Directional wavelet transform in the context of complex quadrature Doppler signals

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.