(21 June 2006 4:20 pm)

SINGAPORE: Broadcasters – with their need to transport uncompressed studio-quality video – are the most demanding customers for video, voice and data networks. Broadcasters face an expensive and complicated future with the task of upgrading networks to enable digital terrestrial television, HDTV and Video on Demand (VOD) and upgrading data and telephony to meet today's standards, unless they can implement a single network that can meet all of these needs.

NetSight Sweden global director operations Thomas Wahlund threw light on how European broadcasters such as Eurovision and Broadcast Services Danmark have recently implemented unified Next Generation networks to provide video for contribution, distribution, and digital terrestrial television plus audio for radio, internet and even telephony.

"Using Asynchronous Serial Interface (ASI), a very common interface used to transport MPEG compressed video to satellite uplinks, between studios and for distribution in for example CATV networks, PCR jitter has to stay under 500 nanoseconds in order for a correct decoding to be done. Since the format is compressed, if only one of these frames arrives out of spectrum it could make the decoder loose synchronisation and it could take several seconds before the service is restored. In the ad-driven world of broadcasting even a few seconds of black screen is obviously unacceptable," Wahlund said.

Delivery channels - terrestrial, cable and satellite, need to keep pace with the ever-increasing demands of the content to be streamed, the demands upon spectrum and the constant high and sometimes unreasonable expectations of the viewer.

Each professional uncompressed standard video stream requires 270Mbps, which is more than 50 times the requirement for a cable -TV movie. Due to the demands of video, broadcasters deploy separate networks for voice and data.

Broadcasters are now looking to upgrade their analogue TV networks with digital TV networks. Singapore, Japan, Australia and Taiwan have rolled out Digital Terrestrial Television (DTT), and most Asian countries will do so in the coming years. With DTT or DVB-T, digital TV signals are transmitted from terrestrial antennas to digital TV receivers in the households. The benefits of this are lower operational costs, a higher picture quality and the ability to transmit up to four times more TV channels on the same frequency range.

Wahlund further added, "The requirements on video transport will also soon increase, as broadcasters change from SDTV to large - scale deployment of HDTV. As a norm, an HD feed takes up roughly four times the bandwidth of a standard definition feed. Today's delivery mechanisms will not be sufficient to handle the increased bandwidth. Broadcasters are now faced with a dilemma of upgrading their data and telephony networks to meet today's standards."

In Europe, several major broadcasters have actively acquired their own networks. The European Broadcast Union (EBU) and Broadcast Service Danmark (BSD), the provider of analog and digital distribution of TV and radio in Denmark, each built its own next generation networks to provide video for contribution and distribution plus audio for radio, internet and even telephony.

"They are now using the networks to connect production studios with film banks, stadiums and other production sites. These optical networks handle a mix of video, audio, data and even telephony without massive over provisioning of bandwidth, delay, jitter and constant (and costly) traffic engineering. Broadcasters have been able to increase the services such as HD and VOD and they have also been able to improve workflow, and substantially save on operating and capital expenses," Wahlund said.

"They are meeting the challenges of providing new services such as HDTV and digital television by building next generation multi-service fibre networks that can provide these services. They are achieving additional benefits by intelligently using the additional bandwidth these networks to provide state of the art contribution and distribution networks and upgraded data and telephony services. They are also benefiting from reduced operating expenses from a unified management system. This is proving to be a rare win-win proposition for all," he concluded.