Time-scale analysis of quadrature Doppler ultrasound signals


Aydin N. , MARKUS H.

IEE PROCEEDINGS-SCIENCE MEASUREMENT AND TECHNOLOGY, cilt.148, ss.15-22, 2001 (SCI İndekslerine Giren Dergi)

  • Cilt numarası: 148 Konu: 1
  • Basım Tarihi: 2001
  • Doi Numarası: 10.1049/ip-smt:20010106
  • Dergi Adı: IEE PROCEEDINGS-SCIENCE MEASUREMENT AND TECHNOLOGY
  • Sayfa Sayısı: ss.15-22

Özet

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. The complex fast Fourier transform can be used to obtain directional information in the frequency domain, as well as time-frequency analysis of Doppler signals. However, it has an inherent time-frequency resolution limitation. The wavelet transform allows the time-frequency resolution compromise to be optimised. Mapping directional information in the scale domain is also desirable. A method is described, based on the utilisation of complex wavelets and negative scales. It eliminates the intermediate processing stages for obtaining directional Doppler signals for time-scale analysis.