Example of a typical voltage power spectrum around the electron plasma frequency measured by the Wind/WAVES/TNR instrument in the solar wind on June 25, 1995. The solid line is the predicted spectrum fitted to the selected data (in diamonds) among data not retained (dots) for the QTN fitting (see text). The annotations indicate the electron parameters obtained by fitting the theoretical spectrum from the ion and the electron QTN, using a sum of two isotropic Mxwellians – a core “c” and a halo “h” – to the observed spectrum. The vertical line indicate the locations of the local electron plasma frequency obtained by both a Neural Network (“NN”, solid line) and by QTN fit (“fitted”, dashed line).