Abstract :
In 1996 the UK government passed legislation which provided for the introduction of national digital terrestrial television (DTT) broadcasting in the UHF spectrum already occupied by analogue PAL-I transmissions. Spectrum planning resulted in frequencies being identified sufficient to provide for six multiplexes operating to the DVB-T specification to be radiated from 81 of the existing television transmitting sites in the UK. The DTT services were launched on the 15 th November 1998. The government Act empowered the BBC to operate one of the national multiplexes and the Independent Television Commission (ITC) to licence the other five. The act also requires that existing analogue broadcasts be replicated (simulcast) on the DTT and the ITC has made it a licence requirement that DVB Service Information (SI) be used to provide, as a minimum, a pan-multiplex simple “Next and Now” programme guide. These two mandated requirements set unique technical challenges which lead to distributed multiplexing and the adoption of a different approach to the generation and transmission of Service Information (SI) than that hereto employed with digital satellite transmission-the need to configure the 81 transmission sites into 30 groups which in turn lead to the need to generate 180 unique SI streams across the UK. A centralised SI collation site has been adopted to avoid distributed collation systems at 30 unattended transmission sites
