11 October 1999

ABA releases digital TV channel plans for Adelaide, Canberra, Hobart and Melbourne

The ABA has released four more digital television channel plans. The plans, for the Adelaide, Canberra, Hobart and Melbourne television markets, set out the channels the commercial and national broadcasters will use for their digital transmissions from 1 January 2001.

"The ABA has developed these digital television channel plans with the interests of viewers foremost in mind," said Professor David Flint, ABA Chairman. "The ABA has sought to minimise the number of changes that viewers will have to make to their existing reception equipment to receive digital broadcasts. By the same token, the ABA has sought to reduce costs to broadcasters by maximising their ability to use their existing transmission facilities."

Plans for most other metropolitan markets and those regional areas commencing digital transmissions on 1 January 2001 – Sydney/Newcastle/Wollongong; Brisbane/Toowoomba; and Darwin/Batchelor – were finalised in July this year.

Release of these latest plans was delayed because of concerns about the use of some VHF channels for digital services. Use of some of these channels requires broadcasters and viewers, predominantly in adjacent regional markets, to make changes to their analog transmission and reception equipment.

The one remaining metropolitan digital channel plan, for Perth, will not be completed until the ABA has considered the results of recent tests using VHF channels in the region.

"Before it finalised these digital channel plans, the ABA wished to assure itself that appropriate arrangements were in place to deal with any possible interference to reception of analog services in adjacent regional markets," said Professor Flint. "The broadcasters have now largely satisfied the ABA in this regard, and the plans indicate technical restrictions on the new digital services will be in place until any difficulties are resolved. We are continuing to work with broadcasters on the development of a code of practice regarding analog changes and interference issues."

With digital channel plans now in place for the main transmitters in most markets commencing transmissions on 1 January 2001, broadcasters are able to proceed with testing the technology and establishing their infrastructure in sufficient time.

The ABA is continuing to work with industry on the potential for using single frequency networks to maximise spectrum efficiency. The ABA will address the issue of channels for the relay of the new digital services, via local area transmitters, following completion of this work.

The ABA has begun drafting digital channel plans for regional areas, which will commence digital transmissions between 1 January 2001 and 1 January 2004.

As part of the digital channel planning process, the ABA has identified as yet unassigned channels that may be used for other purposes, such as datacasting.

An explanatory paper, which discusses issues raised in submissions and explains the reasons for each decision, accompanies each digital channel plan. Those issues that relate to more than one plan are addressed in The ABA’s General Approach to Digital Terrestrial Television Broadcasting Planning.

The technical assumptions used by the ABA in the digital channel planning process as well as the way in which technical assumptions on other matters have been decided are set out in the Digital Terrestrial Television Broadcasting Planning Handbook. The Handbook and the General Approach documents were released together with the first digital channel plans in July.

All digital channel plans, The ABA’s General Approach to Digital Terrestrial Television Broadcasting Planning and the Digital Terrestrial Television Broadcasting Planning Handbook are available on this site on the digital conversion page. Copies can also be obtained from the ABA by calling Freecall 1 800 810 241. All documents are free, except the handbook which costs $20.

BACKGROUNDER

The ABA is required (by Schedule 4 of the Broadcasting Services Act 1992) to formulate legislative schemes for the conversion of commercial and national television broadcasting services from analog to digital mode.

The ABA determined the Commercial Television Conversion Scheme (the CTC Scheme) on 22 March 1999. The National Television Conversion Scheme is expected to be finalised shortly.

Digital transmissions must start on 1 January 2001 in metropolitan areas, and on a date to be determined by the ABA between 1 January 2001 and 1 January 2004 in regional areas.

As part of the implementation of the conversion schemes, in May 1999 the ABA invited comments on draft digital channel plans. The draft plans identified proposed channel allotment and assignment for digital television and other services for metropolitan and those regional markets which will be commencing digital transmissions on 1 January 2001 or soon afterwards.

These plans were prepared by the ABA in consultation with the Digital Television Channel Planning Consultative Group. This group consists of representatives from the ABA, metropolitan and regional commercial television broadcasters, national television broadcasters, the former National Transmission Agency, the Australian Communications Authority (ACA), the Department of Communications, Information Technology and the Arts Laboratory, the Australian Subscription Television and Radio Association, potential datacasters and the Federation of Australian Commercial Television Stations.

All issues raised in submissions have been taken into account in finalising the digital channel plans and are discussed in the accompanying explanatory statement to each digital channel plan. Those issues that relate to more than one digital channel plan are addressed in The ABA’s General Approach to Digital Terrestrial Television Broadcasting Planning.

As knowledge of digital television technology is continuing to evolve, the ABA has taken a staged approach in preparing digital channel plans. As a result, the plans do not identify additional ‘translator’ channels for areas that may not receive good analog television reception from the main transmitter, as the precise need for these for digital television is not known at this stage.

The ABA wants to be satisfied that the best technical information is available to it, through programs of test transmissions and further studies, prior to finalising channels for these areas. This approach is aimed at achieving maximum spectrum productivity by optimising channel usage.

The ABA is awaiting the outcome of recent digital television tests on channel 11 before it completes the plan for the Perth market. Results of the tests and the implications for viewers of the channel 11 analog service in the Central Agricultural (Mawson) region are expected to be available shortly.

Changes from draft digital channel plans

The following changes to preliminary views set out in draft digital channel plans have been made:

Adelaide

The draft digital channel plan proposed the establishment, if required, of low power analog transmitters at Port Neill on channels 56 and 59 to enable reception of the ABNS and GTS services presently received from Cowell on channels 6 and 8 respectively. The final digital channel plan identifies two other alternative solutions to overcome the interference from the Adelaide digital television services on channels 6 and 8. These services would be restricted to 10 kW. The alternatives are:

• increase the effective radiated power (ERP) of channels 6 and 8 in Cowell by 10dB, or
• increase the ERP of channels 6 and 8 in Adelaide to the maximum of 50 kW together with an increase in the ERP of channels 6 and 8 in Cowell by 10dB. In addition, if required, establish low power analog transmitters at Port Neill on channels 56 and 59.

Melbourne

As a consequence of the digital channels planned for Melbourne, analog changes are required in the La Trobe Valley, Ballarat, Bendigo and Foster areas and possibly for King Island. In the draft digital channel plan, it was proposed that existing television services co-channelled with Melbourne digital television services in the La Trobe Valley, Foster and King Island areas must move to alternative analog channels. In the Ballarat and Bendigo areas the ABA identified alternative options to overcome interference. These alternatives were to either establish low powered analog transmitters, or change the channel of the interfered-with analog service.

In the final digital channel plan, the ABA has decided to:

• provide UHF channels 36 and 42 for the transmission of the Ballarat analog services VTV 6 and ABRV 11 respectively, so viewers affected by interference have an alternative for these services (the channel 6 and 11 services will be retained);
• provide UHF channel 38 for the transmission of the Bendigo BCV 8 analog service so viewers affected by interference have an alternative for this service (the channel 8 service will be retained);
• identify alternative solutions to overcome interference from co-channelled Melbourne digital television services in Foster and King Island, namely:
• provide appropriate power increases for the interfered-with analog services, or
• move these services to alternative UHF channels.

Digital channel summary

The following table shows planned digital channels for main stations in the Adelaide, Canberra, Hobart and Melbourne markets.

*The Digital Conversion Act states that the digital transmission of community television services currently operating on the sixth analog channel, will be in spectrum allocated for use for the provision of datacasting services.

Summary of analog channel changes

The following table shows planned analog channels for areas affected by the use of digital channels in the Adelaide, Canberra, Hobart and Melbourne markets.

Planning tools

In carrying out its digital planning task, the ABA is using a sophisticated digital terrain model specifically designed for planning purposes in 1995. This effectively models the entire topography of Australia in digital form. For digital signals, as much as for analog signals, the nature of the landscape across which the transmissions occur is the one of the most significant influences on the signal quality.

The ABA is using a range of internationally accepted tools to predict the propagation path of digital TV signals. These include well-established and still valid models such as ITU Recommendation 370, and those developed by Bullington and the BBC. They also include the most recent tools, such as CRC-COV: a Canadian propagation model developed specifically to predict the behaviour of digital transmissions.

The use of a digital terrain model and the accurate analysis of the propagation path remain the most important factors in efficient digital planning.

What we do l What's new l Search l Publications l Contact us l Home