ower broadcasting satellites. And a substantial market has none of these bands is used much at present. developed in the supply of satellite relay facilities for linking The frequency bands allocated for links between satellites (ITU, together networks of small, low cost earth stations on the users' 1990a) and mobile stations (the mobile-satellite services) on land, premises. by sea or in the air and already used for commercial systems, are There were early experiments with mobile earth stations as part of shown in Table 51.2. The following notes apply to this table: the NASA Applications Technology Satellite programme in the second half of the 1960s. The MARISAT system was set up by the Not in ITU Region 1 (Europe, Africa, Asia west of the Persian Communications Satellite Corporation, starting in 1976, to provide Gulf and the whole of the USSR). Use for mobile satellite telephone and data services by satellite to merchant ships. The systems is subject to protection of terrestrial systems for which internationally owned INMARSAT consortium took over that func- the band is also allocated. (ITU, 1990d,e.) tion in 1982. More recently there has been widespread interest in ITU Region 3 only (Australasia and Asia, excluding USSR and satellite communication for airliners and for various kinds of mobile countries west of the Persian Gulf). Otherwise as note a. station on land; INMARSAT and a number of national systems are Land vehicles may use these bands for low bit rate data systems developing new facilities to meet these needs, often coupled with provided that they do not interfere with use by ships. (ITU, position finding aids. 1990f.) The links, called feeder links, between these satellites and stations International regulations at fixed locations on the ground are operated in bands allocated to the fixed-satellite service (Table 51.1). It is already evident that the bandwidth allocated for satellite to mobile station links will not be 51.2.1 Frequency bands sufficient for rapidly growing systems and prospective new