A.A. Averin1, D.S. Gorkin2, V.V. Varenkov3, V.I. Sakhterov4

1–4 Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation (IZMIRAN) (Troitsk, Russia)

2 LLC Interraskan (Moscow, Russia)

1 averin@izmiran.ru, 2 gorkin@izmiran.ru, 3 varenkov@mail.ru, 4 sakhterov@mail.ru