Design of a continuous wave blood flow bi-directional Doppler system

This paper describes the design of a continuous wave blood flow bi- directional Doppler system based on an open, high- resolution architecture that is portable and low cost. The system incorporates the advantages of expensive systems with dedicated hardware. The system is composed of a flow detector probe, a signal conditioning stage, a direction detection module, a signal processing stage and a graphic user interface. The direction detection of the signal is achieved using a fast digital phasing filter. The Doppler signal is processed using a short- time Fourier transform- based algorithm. This is commonly used as a reference. Nevertheless, the system allows us to incorporate alternative high- resolution spectral estimation methods that might offer more precise information to the specialist. (c) 2006 Elsevier B. V. All rights reserved.