tly more than 360°. That is, a 24-h day is slightly longer than the time it takes for the Earth to rotate once around its axis. A sidereal day is approximately 23 h, 56 min and 4 S (86 164 s). Broadband Telecommunications Technologies and Management traffic carrier. Soon another international satellite operator, Inmarsat, was formed for maritime (ship-shore) communications, again as a body under the United Nations. As the need grew for communications from remote locations such as mines or oil rigs, both Intelsat and Inmarsat started ad-hoc satellite network services using portable earth stations. These systems were mostly intended for digital voice communications, but grad- ually low rate data communications services were also offered. The main traffic over the GEO satellites remained voice and broadcast TV: these were known as fixed satellite ser- vices (FSS). With the growth in the mobile telephony market, a niche market appeared in global MSS coverage in the late 1980s. With the roll out of fibre optic cables, most of Intelsat's long-distance telephony and broad- cast TV business was lost to these cheaper and higher quality media by the early 1990s. Moreover, cellular mobile technologies substituted most of Intelsat and Inmarsat MSS and reduced their revenues. Both companies filed for bankruptcy protection and went through restructure. Both have now emerged focusing on the provision of fixed broadband satellite telecommunications services to remote and underserved areas using very small aperture terminals (VSATs), as well as MSS. Very Small Aperture Terminals GEO satellites can be used for ad-hoc telecommunications network set-up using portable ter- minals. These systems operate using VSATs to digitally communicate connecting remote locations to the public telephone network and the internet. A VSAT terminal consists of a transmitter/receiver (transceiver) to communicate with the satellite and a portable antenna with a size ranging from a few tens of centimetres to a few metres. The antenna size generally deter