CORRECTION FOR NONSTATIONARITY AND WINDOW BROADENING IN DOPPLER SPECTRUM ESTIMATION

The width of the time-varying spectrum of signals from the pulsed Dopp ler ultrasonic blood flow detector is overestimated as a result of win dow and nonstationarity broadening when analyzed using the conventiona l short-term Fourier transform (STFT). By deriving the broadening func tion width from a consideration of signal phase variation arising from the deterministic spectral center-frequency variation during each win dow, the increase in the root-mean-squared (RMS) spectral width can be calculated and the spectral width estimation corrected, Using this pr ocedure on simulated Doppler signals of known characteristics, a signi ficant reduction in spectral width estimation error can be demonstrate d.