Method to determine spectrum of turbulence?

Walid

I make turbulence measurement by using Pulsed Doppler Ultrasound Velocimetry technic. I calculated the power spectrum of turbulent fluctuations and i showed that energy spectrum decay versus frequency approximately a power law of the form E(f)=f^(-5/3), which is the law predicted by Kolmogorov.

The technic used for to determine the energy spectrum is based on Fast Fourier Transform of Doppler Signal + a technic of Slipping Average which consist of making slip a window of observation on the signal.

I observed that the use of such windows will introduce noise into the signal spectrum signal and the slope of energy spectrum changes with the number of used window and not only for hydronamic or acoustic reasons.

I want to know if my treatement technic is right or not? if not, there is other method of signal treatement which does not present a noise on spectrum?

Thank U