WorldSpace digital radio system live out of AfricaRichard WilsonWorldSpace, the satellite-based digital radio broadcast system, went live across the African continent last week.
Broadcasts via the Afristar satellite can be received by small battery-operated radio sets across Africa and in parts of the Middle East.
The system is one of the first commercial digital radio projects to be realised on a global scale. The audio data are coded in the MPEG 2.5/Layer 3 standard which was specially developed for WorldSpace, and are transmitted in compressed form in the L-band (1467 to 492MHz).
The up-link is implemented by frequency-division multiplexing (FDM), and the down-link by time-division multiplexing (TDM). This ensures that several up-links can be operated in parallel without mutual interference and that optimum use can be made of the satellite transponders.
Swiss firm Micronas is one of the suppliers developing a radio receiver chipset for the system.
WorldSpace broadcasts via three satellites, each of which covers three target regions. In each region, a transmission capacity of 192 prime-rate channels with a data rate of 16 kbit/s is available. Depending on quality requirements, from one to eight prime-rate channels can be combined into one radio channel so that pure news programs, for example, can be run on reduced channel capacity.