obile handsets. In the past, these factors have invalidated a number of apparently promising satellite based business models. New satellite ventures therefore have to be approached with caution and the relative merits and demerits of each option need to be carefully considered. This is particularly true when significant amounts of spectrum are being allocated by regulators either for satellite-based services or for new hybrid satellite terrestrial network propositions. Satellites have delivered telecommunications, TV and data for over 50 years, the original triple-play proposition. This interdependency has determined the economics of the industry. Over the past twenty years improved power output (downlink capability) and sensitivity (up- link capability) has allowed satellites to play an increasing role in delivering communications to mobile devices including mobile handheld devices. Hybrid satellite terrestrial networks are Making Telecoms Work a logical next step, but have to be qualified in terms of the additional value that they deliver to existing terrestrial networks. 16.20 Terrestrial Broadcast and Satellite Coexistence in L Band Table 16.9 referred to earlier shows the allocations to terrestrial broadcast, satellite broadcast and satellite two-way services in L Band. 16.21 Terrestrial DAB Satellite DAB and DVB H The L Band allocations for DAB and DVB H were identified, although these allocations were not universally available in all countries. DAB was intended primarily for radio but could carry a TV multiplex of up to 7 video channels on a 1.7-MHz OFDM channel. DVB H was implemented as a trial in New York delivering 75 TV and music stations transmitted from 74 terrestrial sites covering 475 square miles. The network used a 5-MHz channel rather than the standard 8 MHz used for DVB H at UHF or S band. DVB H could have been implemented in L band as a DVB SH network with terrestrial repeaters but lacked global scale and therefore could not be progressed. 16.22 World Space Satellite Broadcast L Band GSO Plus 