title: Real-time software processing and audio reproduction of directional Doppler signals.
abstract: In ultrasound Doppler systems, directional signals are typically obtained by processing quadrature demodulated data with dedicated analog or digital circuits. In this paper, a software approach is proposed, that allows fully exploiting the reproduction and recording capabilities of low-cost personal computer sound cards and/or embedded chips. Forward/reverse signals are separated through a wideband Hilbert filter. No limitations are imposed on the input signal sample rate, which is matched to the standard output format of sound cards through a band-limited interpolation filter controlled in a feedback loop. The digital audio streaming is performed in real-time in a Windows-based application. The processed data are in a standard format compatible with real-time recording in waveform or compressed files, as requested in many research applications. Simulations and in vivo tests show a typical cross talk of -50 dB between forward and reverse components, with low latency time (39 ms) and central processing unit load compatible to currently available personal computers.
authors.affiliation: Electronics and Telecommunications Department, University of Florence, Florence, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Fidanzati
authors.forename: Tiziano
authors.initials: T
authors.lastname: Morganti
authors.forename: Piero
authors.initials: P
authors.lastname: Tortoli
mesh_terms: D004867:Equipment Design; D006801:Humans; D008838:Microcomputers; D012815:Signal Processing, Computer-Assisted; D012984:Software; D013016:Sound; D018608:Ultrasonography, Doppler / Q000295:instrumentation / Q000379:methods*