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

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