International audienceWhistler mode chorus emissions are intense magnetospheric waves composed of discrete wave packets with variable frequencies that sometimes change into shapeless hiss. Chorus probably accelerates electrons in the outer radiation belts to energies greater than 1 MeV through wave-particle interactions. Chorus wave packets usually consist of rising tones, but falling tones and more complicated structures have also been observed. Measurements provided by Wideband and STAFF-SA instruments onboard Cluster spacecraft give us information about the source region, propagation and spectral structures. Previous measurements of Cluster spacecraft show that most of the intense chorus can be found at L-shells between 4 and 5, but rece...