Divides the range swath (range cells) of this block into Nspect sections and finds the average power spectrum for each segment. Fits a parabola to the baseband Doppler centroid vs. range This fit is most useful if the whole range swath

彩超CW的IQ数分析，做fft变换，看频谱的能量(Color Doppler ultrasound CW IQ number analysis, do FFT transform, look at the spectrum of energy)