Correction for nonstationarity and window broadening in Doppler spectrum estimation

The width of the time-varying spectrum of signals from the pulsed Doppler ultrasonic blood flow detector is overestimated as a result of window and nonstationarity broadening when analyzed using the conventional short-term Fourier transform (STFT). By deriving the broadening function width from a consideration of signal phase variation arising from the deterministic spectral center-frequency variation during each window, the increase In the root-mean-squared (RMS) spectral width can be calculated and the spectral width estimation corrected. Using this procedure on simulated Doppler signals of known characteristics, a significant reduction in spectral width estimation error can be demonstrated.