Italian participation in Olympus and Italsat propagation experiments - Impact on direct broadcasting

Present knowledge of atmospheric attenuation of satellite signals at frequencies above 10 GHz, based on the Sirio, OTS, and COST-205 experiments, is summarized; and a plan for Italian participation in propagation experiments at 12.5, 20, 30, 40, and 50 GHz using Olympus and Italsat (scheduled for launch in 1987 and 1988, respectively) is outlined. Statistical methods for predicting the attenuation of DBS-TV signals on a national scale, either from conventional point-by-point meteorological data or from frequency-scaling data obtained at a few stations, are discussed; small-scale and large-scale diversity in the attenaution predictions obtained so far is considered; the possible effect of ice on the relationship between attenuation and depolarization is examined; and the need for further measurements, expecially at higher frequencies, is stressed. The construction of Olympus/Italsat receiving stations at Rome, Turin, and Spino d'Adda, perhaps in conjunction with additional secondary stations, is proposed.