atellite broadcasting are digital network? To what degree will satellites provide special at 12GHz. Frequency assignment plans for broadcasting down-links communication facilities that the world is going to want and which in these bands, and the corresponding feeder links in other bands at are not available at an acceptable price from that integrated global 18GHz and 15GHz, were agreed at various administrative con- network? ferences of the ITU between 1977 and 1988. These plans define the Who can tell? It seems likely, however, that in the nearer future ways in which the band is to be used in some considerable detail, the use of satellites for main links in the public telecommunications but in essence: network will grow, as the world economy grows, but perhaps at a slower rate than hitherto and under strong pressure to minimise With few exceptions, down-link footprints may not exceed costs. On the other hand, there may well be considerable growth in national boundaries; the use of powerful satellites and small earth stations for a variety 2. With allowances made for the climate of the country con- of other purposes. Thin route public network systems will bring cerned, the power flux density at the ground at the edge of the modern telecommunications facilities to sparsely populated and coverage area should be-103dB(W/m²) for ITU Regions 1 and under developed areas. Private networks using VSATs may provide 3;-107dB(W/m2) for Region 2. cost effective data transmission in some circumstances. Above all, 3. Every country has been assigned a share of the channels that the use will be found for satellites for limited access multi-destination plan can provide. In Region 1 the shares are equal, every transmissions, 'narrow casting' as it is sometimes called, for con- country being assigned 5 channels, except where the country is ference television and for other situations where wide bandwidth is SO large that provision must be made for extra channels to required for short periods. Indeed the indications are that the use o