Browsing by Author "Gonzalez, J. S."
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- High performance parallel-DSP computing in model-based spectral estimationPublication . Gonzalez, J. S.; Nocetti, D. F. G.; Ruano, M. GraçaDoppler blood flow spectral estimation is a technique for non-invasive cardiovascular disease detection. Blood flow velocity and disturbance may be determined by measuring the spectral mean frequency and bandwidth, respectively. The work presented here, evaluates a high performance parallel-Doppler Signal Processing architecture (SHARC) for the computation of a parametric model-based spectral estimation method known as the modified covariance algorithm. The model-based method incorporates improvement in frequency resolution when compared with Fast Fourier Transform (FFT)-based methods. However, the computational complexity and the need for real-time response of the algorithm, makes necessary the use of high performance processing in order to fulfil such demands. Sequential and parallel implementations of the algorithm are introduced, A performance analysis of the implementations is also presented, demonstrating the effectiveness of the algorithm and the feasibility for real-time response of the system. The results open a greater scope for utilising this architecture in implementing new and more complex methods. The results are applied to the development of a real-time spectrum analyser for pulsed Doppler blood flow instrumentation. (C) 1999 Elsevier Science B.V. All rights reserved.
- High-performance computing for real-time spectral estimationPublication . Madeira, M. M.; Bellis, S. J.; Beltran, L. A. A.; Gonzalez, J. S.; Nocetti, D. F. G.; Marnane, W. P.; Tokhi, M. O.; Ruano, M. GraçaThis paper presents two separate investigations into the real-time implementation of the modified covariance spectral estimator: one comparing performances on digital signal processors, the TMS320C40, and the recently released ADSP2016x (SHARC); another using application-specific custom circuitry. The advantages and disadvantages of each of these different approaches are reviewed, resulting in the design of a field-programmable gate array/digital signal processor-based high-performance system that combines the hardware and software approaches. In conjunction with pulsed Doppler ultrasound blood-flow detectors, the spectral estimator offers increased sensitivity in the non-invasive detection of arterial disease. (C) 1999 Elsevier Science Ltd. All rights reserved.
- High-performance real-time implementation of a spectral estimatorPublication . Madeira, M. M.; Beltran, L. A. A.; Gonzalez, J. S.; Nocetti, F. G.; Tokhi, M. O.; Ruano, M. GraçaDoppler blood flow spectral estimation is a common technique of noninvasive cardiovascular disease detection. Blood flow velocity and disturbance may be evaluated by measuring spectral mean frequency and bandwidth respectively. Aiming at minor stenosis diagnosis, parametric spectral estimators may be employed. These models present better spectral resolution than the FFT based ones, at the expense of higher computational burden. Seeking for an efficient real-time implementation of a blood now spectral estimation system, high performance techniques are being investigated. This paper compares the implementation of the Modified Covariance (MC) spectral estimator on two different DSP architectures: the TMS320C40 and the ADSP2016x (SHARC). Implementations are described and their performance assessed. Considerations about portability of algorithms, compiler optimisation levels and system dependence features are addressed. Copyright (C) 1998 IFAC.
- Solving practical issues of a portable Doppler ultrasound system for blood flow assessment during coronary graft surgeryPublication . Zabihian, B.; Ruano, M. Graça; Gonzalez, J. S.; Nocetti, D. F. G.; Cruz, M. F.This paper presents some practical issues regarding the development of a dedicated Doppler Ultrasound system (DUS) for the assessment of blood flow signal on coronary grafts during heart surgery. The DUS is composed of several processing units. This paper concentrates on front-end units: the transducer and a particular issue of the software interface for clinical evaluation, the noise cancellation technique (NCTech). The experimental set-up implemented to evaluate the transducer response is presented. The procedure employed to eliminate the noise components embedded in the DUS data is described. Each of these units was primarily tested in laboratory. Results show their effectiveness in achieving their specific goals. Comments on the overall system's performance are presented denoting the usefulness of such dedicated DUS during bypass assessment at heart surgery. © 2011 IEEE.