Journal ArticleDOI
Effect of method and parameters of spectral analysis on selected indices of simulated Doppler spectra.
K. Kaluzynski,Tadeusz Pałko +1 more
TLDR
The sensitivity of Doppler spectral indices to the conditions of spectral analysis (estimation method, data window, smoothing window or model order) increases with decreasing signal bandwidth and growing index complexity.Abstract:
The sensitivity of Doppler spectral indices (mean frequency, maximum frequency, spectral broadening index and turbulence intensity) to the conditions of spectral analysis (estimation method, data window, smoothing window or model order) increases with decreasing signal bandwidth and growing index complexity. The bias of spectral estimate has a more important effect on these indices than its variance. A too low order, in the case of autoregressive modelling and minimum variance methods, and excessive smoothing, in the case of the FFT method, result in increased errors of Doppler spectral indices. There is a trade-off between the errors resulting from a short data window and those due to insufficient temporal resolution.read more
Citations
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Journal ArticleDOI
A study of the spectral broadening of simulated Doppler signals using FFT and AR modelling
TL;DR: Despite the qualitative improvement of the AR spectra over the FFT, the estimation of SBI for short data frames is not significantly improved using AR, and a strong correlation between the indices calculated using the F FT and AR algorithms is shown.
Journal ArticleDOI
Spectral broadening of ophthalmic arterial Doppler signals using STFT and wavelet transform.
Elif Derya Übeyli,İnan Güler +1 more
TL;DR: In this study, short-time Fourier transform (STFT) and wavelet transform (WT) were used for spectral analysis of ophthalmic arterial Doppler signals and no quantitative advantage in using the WT over the STFT for the determination of spectral broadening index was obtained.
Journal ArticleDOI
Spectral broadening of clinical Doppler signals using FFT and autoregressive modelling
TL;DR: In this article, the authors investigated the spectral broadening index (SBI) derived from spectra obtained using autoregressive (AR) modelling compared to that of SBI based on fast Fourier transform (FFT) analysis of clinical Doppler ultrasound scans.
Scientific paper Spectral broadening of clinical Doppler signals using FFT and autoregressive modelling
TL;DR: It was established that, for all cases where significant stenosis was present, a statistically significant value for SBI could be obtained using four or more heartbeats if five spectra around the peak systole were used to estimate the SBI of each individual heartbeat.
Journal ArticleDOI
Performance of time-frequency representation techniques to measure blood flow turbulence with pulsed-wave Doppler ultrasound.
TL;DR: Several TFR methods can be used to measure the magnitude of the turbulence fluctuations and different parameters must be used for each method to minimize the velocity variance of the estimator, to optimize the detection of the turbulent frequency fluctuations, and to estimate the Kolmogorov spectrum.
References
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Journal ArticleDOI
Spectrum analysis—A modern perspective
Steven Kay,S.L. Marple +1 more
TL;DR: In this paper, a summary of many of the new techniques developed in the last two decades for spectrum analysis of discrete time series is presented, including classical periodogram, classical Blackman-Tukey, autoregressive (maximum entropy), moving average, autotegressive-moving average, maximum likelihood, Prony, and Pisarenko methods.
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Digital spectral analysis : with applications
TL;DR: This new book provides a broad perspective of spectral estimation techniques and their implementation concerned with spectral estimation of discretespace sequences derived by sampling continuousspace signals.
Journal ArticleDOI
A comparative study and assessment of Doppler ultrasound spectral estimation techniques. Part II: Methods and results.
TL;DR: Results indicate that both the AR(Yule-Walker) and ARMA(singular value decomposition) models of orders (8) and (4,4), respectively, show good agreement with the theoretical spectrum, and yield estimates with variances considerably less than the Fast Fourier Transform (FFT).
Journal ArticleDOI
Comparison of four digital maximum frequency estimators for Doppler ultrasound.
TL;DR: Overall, it was found that the modified threshold method and the new hybrid method have the best performance over a wide range of signal and noise conditions; however, D'Alessio's method also performs well for low SNR's.
Journal ArticleDOI
A Comparison of Methods for Generating Normal Deviates on Digital Computers
TL;DR: Two methods recently developed for generating normal deviates within a computer are reviewed and the detailed inverse technique proposed yields accuracy comparable with, or better than, most previous proposals using about one-quarter the computing time.