A fast frequency domain algorithm for decoding quadrature Doppler signals

A fast frequency domain method for quadrature-to-directional format conversion of Doppler ultrasound signals is described. The algorithm requires only one complex FFT and one inverse FFT. Since the technique relies on the manipulation of phase information in the frequency domain after the complex FFT, it is named the Spectral Translocation Method (STM). The theoretical description is verified by simulation and practical implementations. The algorithm has been implemented in real-time using a commercially available digital signal processor board. Results show that more than 50 dB channel separation is achievable and widespread use of DSP chips makes this method attractive.