FEATURE


completely new skill-set to complement the existing RF broadcast expertise. Broadcast Australia transformed its team into ‘digital experts’ in order to integrate the transmission system and undertake the massive deployment.


Launched on 1 January 2001, the first national and commercial DTTB services covered Australia’s main metropolitan markets of Sydney, Melbourne, Adelaide, Brisbane and Perth. Since that date, Broadcast Australia has progressively rolled-out services through regional centres, translator sites, major tourist areas and remote rural regions, with the 499th and 500th transmitters recently switched on at Mount Read in Tasmania.


Each of the sites – most of which support multiple DTTB services using common infrastructure – was individually assessed in terms of logistics, access and existing infrastructure that could be reused or modified. A single project engineer was responsible for streamlining the entire design and implementation process at each site. One of the most important considerations was the minimisation of disruption to existing services during the upgrade.


It was also necessary to upgrade the program distribution systems that support the transmission sites. The enormous volume of data associated with DTTB services, particularly HDTV, meant that additional data handling capacity was required. Owing to the high number of remotely located sites in Broadcast Australia’s network – many being hundreds of kilometres from a city – these program distribution systems are largely satellite links; upgrading the capacity of these links involved negotiations with the satellite provider. In other cases, microwave and fibre optic links were upgraded.


Broadcast Australia’s Gore Hill transmission site in Sydney is at the hub of its massive nationwide DTTB network


Mandatory Monitoring


The final stage of deployment of each digital service has involved its integration with Broadcast Australia’s network operations centre (NOC), located at the Gore Hill transmission facility in Sydney. The NOC monitors and operates the entire network, which covers an area of almost 77 million square kilometres, comprises nearly 600 individual unmanned sites, and supports over 2200 digital and analogue television and radio services.


Since the first DTTB services were deployed, the NOC itself has undergone several upgrades in order to support the vigilant monitoring required by digital systems. Opportunities for error exist throughout the entire life of a digital signal – from the content source base code, through the encoding and multiplexing of the transport stream, and the transmission and reception of the RF signal itself. This means end-to-end monitoring of digital services is essential to ensure signal integrity. Moreover, since Broadcast Australia provides independently managed transmission services, there is a need to isolate individual programmes within a multiplex and demonstrate assurance that these programs are going to air correctly.


High-power UHF panel array at one of Broadcast Australia’s main transmission facilities


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Increasingly, digital equipment is providing this information in the form of simple network management protocol (SNMP), which requires new network management philosophies. Faced with a flood of data, it has often been a challenge to identify the essential information; however, experience has helped the isolation of critical data from that which is merely ‘nice to have’.


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