[1] Univ Yaounde I, Natl Adv Sch Engn, Dept Elect & Telecommun Engn, POB 8390, Yaounde, Cameroon
[2] Univ Douala, Fac Sci, Dept Phys, POB 24157, Douala, Cameroon
[3] Univ Yaounde I, Fac Sci, Dept Phys, LEMAP, POB 812, Yaounde, Cameroon
[4] Univ Dschang, Sch Wood Water & Nat Resources, Fac Agron & Agr Sci, POB 786, Ebolowa, Cameroon
[5] Univ Yaounde I, Higher Teachers Training Coll, Dept Phys, POB 47, Yaounde, Cameroon
[6] Univ Maroua, Natl Adv Sch Engn, Dept Meteorol Climatol Hydrol & Soil Sci, Maroua, Cameroon