On the application of the Wigner-Ville distribution to broadband reflectometry

Herein we propose a data processing method to analyse broadband reflectometry signals based on the Wigner-Ville distribution (WVD). The method offers the advantage of good localization of the reflectometry signal energy in the time-frequency domain. Simulations are presented to test the ability of this technique to follow the average beat frequency that is the relevant quantity to invert the plasma profile. The method is compared with the short-time fourier transform (STFT) analysis both for simulated and for ASDEX Upgrade plasmas. It is shown that the WVD has potential advantages for the routine evaluation of density profiles. The method can also be useful to study fluctuations. namely when abrupt changes of turbulence occur at the L-H transition. (C) 1999 Elsevier Science S.A. All rights reserved.