Australian experts have been involved throughout the development of HDTV and digital television options, from the debates on HDTV standards in the mid 1980’s through to the present. Particular attention has been paid to the International Telecommunications Union (ITU-R) forums where Australian experts have consistently pressed for a common international standard. The ITU was seen to be the main forum in which to argue for convergence of television standards for the new technology choices, so as to avoid the need for continuing standards conversion and consequent operational and quality difficulties.

The Australian television industry closely parallels the US industry in its structure. Commercial networks with affiliated stations are a dominant force, whilst the two Government-funded national networks (ABC and SBS) also draw significant audiences. On the other hand, the technology base of the industry is essentially of European origin, being built on 50 Hz PAL analogue.

Active domestic committees have supported Australian participation in international standardisation. The shadow committee for the Geneva-based broadcasting study groups (ITU-R Study Groups 10 and 11 – ARSG 10&11) has wide representation from all sectors of the Australian broadcasting industry. It receives and processes input from other more specialised groups and in particular the expert groups established by the Engineering Committee of the Federation of Australian Commercial Television Stations (FACTS). FACTS has made a practice of involving the national broadcasters and (where appropriate) government agencies in its various studies, to ensure that all aspects of common interest for free-to-air broadcasting are addressed.

FACTS is the representative body of Australian Commercial Television licensees, and operates in a manner similar to the National Association of Broadcasters in the US. FACTS has five main functions: policy establishment, lobbying on behalf of the industry, television commercial assessment, industrial relations, and engineering. Engineering activities function under the direction of an Engineering Committee which manages the work of Specialist Groups and other subgroups designated to study specific issues and topics.

From about 1990 it became apparent that work on development of analogue HDTV standards based on proposals from Europe, the USA and Japan was becoming deadlocked because of the unavoidable linkages between system standards and the respective regulatory, planning and operational environments of the countries of origin. In addition, none of the analogue HDTV proposals was particularly attractive for use in Australia. In the same time frame, work in the ISO/IEC JTC-1 MPEG group on compression systems and in other related fields indicated that digital technologies might offer viable new solutions for consumer services in broadcasting.

From its monitoring of developing technologies, FACTS Engineering Committee became confident that digital compression and transmission would evolve into practical technologies to carry terrestrial broadcasting into the new millennium. It established a specialist group to study the subject, particularly the early developments in the US. While European broadcasting technology was concentrating on the development of Multiplexed Analogue Component (MAC), FACTS saw little benefit in the MAC technology for terrestrial broadcasting. The commercial broadcasting structure of Australian television depends heavily on local programming and local advertising revenue. The European technology was fundamentally directed to satellite distribution, not suited to distribution to smaller locally-concentrated broadcasting markets.

Early work on the use of OFDM published by the IBA in the UK and in other European studies showed similar promise to parallel work on a system to develop HDTV terrestrial broadcasting in the USA. The Australian broadcasting experts identified a need for the ITU to provide a common forum where these disparate studies could be drawn together in an attempt to evolve, for the first time, a world- wide common system of television broadcasting. As a result of an Australian proposal to ITU-R Study Group 11, Task Group 11/3 was established with the objective of preparing a common set of digital terrestrial television broadcasting (DTTB) standards.

The success of Task Group 11/3 has been well documented elsewhere. It was very successful in fostering a high level of convergence between the North American and European DTTB systems. In one essential area, it was not successful. Two systems for modulation emerged, and could not be reconciled. In the US, a single carrier 8VSB modulation system was formally adopted. European countries confirmed their adoption of a multiple carrier Coded Orthogonal Frequency Division Multiplex modulation system (COFDM). In part, these differences reflected the different market environments into which the digital technology would be implemented. In the US, there is a highly competitive localised broadcasting industry. In Europe, national broadcasters still predominate, and there is a tightly interference-limited international plan for all of Europe. Towards the end of the studies of Task Group 11/3, Japan announced that it was working on a third modulation variant which would offer segmentation of the RF channel.

During this time, the Australian studies initiated by FACTS committees had progressed to a more formal study of the potential of DTTB, conducted by an Australian Broadcasting Authority (ABA) Specialist Group. That group identified a range of issues, both policy and technical, that needed to be addressed for the possible introduction of DTTB in Australia. Issues identified included the unique characteristics of the mature Australian broadcasting industry. The final report of the ABA Specialist Group was released in late 1996 and published in February 1997.

Towards the end of that process, the FACTS Engineering Committee resumed its direct involvement in DTTB by reestablishing the Specialist Group DTTB. The Chairman of the Specialist Group was instrumental in organising the first experimental broadcasting of DTTB in Australia. This broadcast from the Nine Network headquarters in Sydney occurred during the final meeting of Task Group 11/3 in Sydney, Australia, in November 1996. A program of tests to evaluate both DVB and the ATSC systems was drawn up and progressed over the following year. These tests, the only directly comparative tests conducted in the world to date, provided a solid technical basis for the Australian selection of the DTTB system to be used in Australia.

In 1998, the Specialist Group-DTTB established a structure for developing detailed technical standards, including a DTTB Selection Panel. The Selection Panel comprised members representing the National broadcasters (ABC and SBS), the Commercial Networks and Regional commercial broadcasters, the Department of Communications Information Technology and the Arts, and the Australian Broadcasting Authority.

The Selection Panel was given the responsibility of analysing the comparative tests and other available information, establishing the relevance of the performance differences to Australian broadcasting, and recommending the system to be used. The importance of the panel’s role was highlighted by the introduction of legislation to the Australian Parliament setting the timetable for the introduction of DTTB the start of 2001.

Throughout the processes leading to the recommendation of a DTTB system for Australia, many people and organisations made substantial contributions. Both the DVB and ATSC organisations, together with manufacturers supporting them, provided invaluable information and resources to assist the Australian studies. For the detailed tests, several suppliers provided equipment and manpower assistance. Within the industry, countless human resources were provided, together with the loan of equipment and infrastructure. A list of acknowledgments is contained in Annex [F].

Index     Digital TV

TABLE OF CONTENTS

This Report addresses the studies, testing and evaluation by the FACTS-based DTTB Selection Panel which lead to the recommendation of a system of digital terrestrial television broadcasting for Australia.

The Selection Panel was formed from the FACTS Specialist Group DTTB (the Specialist Group) in February 1998 and held its first meeting on May 1 1998.

In preparation for the first meeting, members submitted suggestions for the criteria that should be used in assessing the choice. The consequent list was refined and used as a guide for the final recommendation. The Panel met four times with its final meeting taking place on June 18, 1998.

The Panel was unanimous in its view that all free-to-air television broadcasters should use a common standard to ensure commonality of equipment and minimum cost to viewers. The evaluation process which was used assisted in clarifying the merits of each system in the context of the Australian broadcasting environment, and the process of planning for the transition to digital television.

The FACTS Specialist Group DTTB organised extensive laboratory and field testing of the two systems during 1997. The laboratory evaluations were conducted in the Government’s Communications Laboratory facilities in Canberra, with the Laboratory experts carrying out most of the work, assisted by experts from the industry. The field tests were supervised by experts from FACTS members, assisted by the Communications Laboratory staff, the Australian Broadcasting Authority and a consultant employed by FACTS.

The laboratory and field tests were conducted to an agreed test program drawn up by the Specialist Group. They were designed to provide information on the particular technical characteristics which were important in the Australian broadcasting environment. In this respect, the Australian tests had a number of unique characteristics.

• First direct comparative tests between the two systems
• First extensive tests of both systems in a 7 MHz channel environment
• First tests of VHF adjacent channel operation
• First test of ATSC in a PAL environment
• First test of DVB at VHF

From the outset it was recognised that the ATSC system parameters are mainly fixed and deliver a total useable data rate of 19.39 MBPS whilst the DVB system offered a range of operating modes, ranging from low data payloads with rugged coverage ability to higher payloads with less rugged coverage capability. The DVB system chosen for testing was one that provides a payload of 19.35 MBPS. This choice was based on the findings of the ABA Specialist Group which indicated that a payload in the order of 20 MBPS is desirable in order to meet the HDTV objectives of the service. Of the DVB operational modes available with data rates similar to that provided by ATSC the mode providing the most rugged option was used.

Given the sensitivity of the measured results, the Specialist Group agreed that both DVB and ATSC should be given an opportunity to comment on the laboratory and field test reports before their publication. Both organisations responded with some corrections that have been subsequently addressed. Importantly, ATSC and DVB also congratulated the group on the thoroughness and impartiality of the tests and the reporting.

Summary reports of the Laboratory and Field test are included as Annexes [C] and [D] respectively with the comments received from DVB and ATSC at Annex [E]. The full detailed test reports are available at:

http://happy.emu.id.au/lab/info/digtv/

In the assessment of the test results, the DTTB Selection Panel felt that there was insufficient information for technical assessment of some relevant criteria. In particular, this applied to translator performance, indoor antenna performance and carriage through Master Antenna Television systems. It was considered that each of these matters would require further testing and evaluation.

Preliminary arrangements were made to obtain equipment to address each of these issues but were not progressed for comparative testing following the decision to recommend DVB.

Starting from an initial list of some 50 possible criteria, the Panel researched, analysed and refined the list to those criteria that were considered to have relevance for the selection. Individual elements were grouped into sets of related criteria that were then further refined by full discussion. It should be emphasised to readers of this report that the criteria were established on the basis of their relevance and importance in the Australian broadcasting context. While other organisations wishing to undertake a similar evaluation may well adopt a similar set of criteria, the significance of each criterion should be judged in the specific context of the needs and environment of the particular country intending to implement DTTB.

As a first step, those criteria that did not show a material differential in performance between the systems were identified as not being significant in making the choice. It was thought, however, that those elements still needed to be thoroughly considered in designing the overall system. For the purpose of the Australian choice, they were assessed as providing basically the same performance for either of the systems considered. Criteria considered to be in this category included:

• Need for co-siting
• Availability of transmission, modulation and multiplex equipment
• Compatibility with digital studio-to-transmitter links and satellite program services
• System operating costs
• Multi program/multi-channel support
• Arrangements for program associated data
• Arrangements for non-program associated data
• Stability and reliability of the technology
• System upgrade and further development capability
• Consideration of set-top boxes
• Interoperability with VCR’s
• Receiver operating system
• Electronic program guides
• Conditional access
• Receiver and set-top box MP@HL capability
• Interlace vs progressive scanning (receivers)
• Baseband input (receivers)

Other elements which might have affected the choice but were not able to be quantified were:

• Technology royalty costs
• Location of receiver manufacturing.

It should be noted that the ISDB system in development in Japan was not tested or considered, as it was not expected to be sufficiently advanced to meet the scheduled Australian commencement date of 2001.

In general, the coverage would be expected to match that achieved by PAL. It is clear that the nature of DTTB, which suffers from the "cliff effect", will mean that the coverage will not be identical. There will be some levels of lesser performance arising from the power limits imposed by non-interference to PAL because of the expected extensive use of channels adjacent to the existing PAL services for DTTB. The main city allocations are expected to use the single channel gaps in Band III. On the other hand, for some aspects such as ghosting limitations there will be areas of improved reception performance. With different characteristics between 8VSB and OFDM, the different elements need to be judged on the relative coverage potential, weighted to the affected proportion of the audience. Eventually it can be assumed that, after cessation of PAL, coverage can be improved by raising power levels to that needed to match the existing PAL coverage.

This will vary between markets, dependant on the particular topography of each market. The A coverage area is essentially that area lying within the old Band III 50 dBm V/m, Band IV 62 dBm V/m or Band V 67 dBm V/m contours of the PAL service.

This is basically that area beyond the VHF 50 dBm V/m, Band IV 62 dBm V/m or Band V 67 dBm V/m contours which is still part of the designated service area, but in which reception is by means of improved receiving installation or by range-extending translators. The extent of reception without range extending translators will affect the efficiency of the DTTB service.

Note: It is assumed that 3.1.1 and 3.1.2 will (as for traditional analogue television planning) assume rooftop antennas. There may also be differences between metropolitan coverage and typical regional coverage requirements.

This allows weighting versus rooftop antennas. It also provides for portable receivers, although outdoor set-top antennas may differ in performance from indoor because of different multi-path characteristics.

This allows for the potential extension of the PAL market allowing service to mass transport and private vehicles.

This addresses the different co-channel performance criteria:

• Digital to Digital
• Digital to Analogue PAL
• Analogue to Digital

This addresses the different adjacent channel performance criteria

• Lower adjacent DTTB into PAL
• Upper adjacent DTTB into PAL
• Lower adjacent PAL into DTTB
• Upper adjacent PAL into DTTB
• Lower adjacent DTTB into DTTB
• Upper adjacent DTTB into DTTB

This may significantly affect the coverage of dense urban areas, but probably has most impact on indoor antenna reception. It also addresses other multipath variations such as:

• Aircraft flutter
• Reflections from large moving vehicles
• Some anomalous propagation effects

This may be significant in dense urban or heavy industrial areas.

• VHF
• UHF

This group of criteria mainly addresses the relative cost elements to broadcasters in implementing the DTTB system with respect to the transmission infrastructure and associated program service distribution systems.

There may be some difference in the ability to multiplex the PAL and DTTB signals into a common antenna, particularly when adjacent channel operation is employed.

The main possible difference is the extent of reprocessing needed in translators.

The use of co-channel allocations for translators has application particularly for gap filling or range extending. The extent to which CCT could be used for straight fill-in applications will be limited during the transition period because of the existing PAL system. CCT gap fillers will be limited to a very few cases where it does not change the relative field strengths between PAL and DTTB. There may be some useful application for linear range extending translators where the existing PAL channel allocations do not conflict. However, there may be significant potential for gap fill applications when PAL is turned off. Availability of relatively unused channels for CCT gap fillers will be a factor.

There may be potential to use existing standby plant for DTTB transmission. The extent of performance modification needed may affect practicality and/or cost.

This group of criteria addresses the flexibility of the systems to offer service modes that may be needed. In this regard the Australian Government policy decision needed to be taken into account

The level of system support for HDTV addresses not only the straight technical standard support but also the support for transmission and reception equipment

While closed captions will be important, this mainly relates to confirming that the system has defined methods for including closed captioning in the transmissions.

This matter needs to be addressed relative to the capability of the systems to provide multiple audio program streams. Both 5.1 channel audio systems provide only single language audio program streams.

The relative suitability of the 5.1 surround sound systems may be a factor.

This group of criteria addresses a number of total system elements.

This addresses the extent to which a system needs to be modified for Australia compared to its main market base.

This criterion addresses the total usable bitrate of each system when operating within a 7 MHz channel.

Fixed for ATSC, variable for DVB.

This may only be significant where the off-air signal is used for monitoring or cueing in live broadcasts.

The ability of the system to be enhanced by technical upgrades without undue disturbance to existing viewers.

This group of criteria addresses the important aspect of availability of receivers suitable to meet the broadcast service objectives for Australian digital television broadcasting. Australia’s relatively small market for major consumer products implies some need for commonality with a larger market base if costs are to be minimised.

This again depends on service expectations and reasonable predictions of the volume of receivers expected in markets with similar service objectives.

There is view that it will be necessary that all DTTB receivers must decode MP@HL to ensure there are not limitations on HDTV broadcasting. Inability to decode MP@HL would mean no reception during HDTV broadcasts.

The need for this depends on whether viewers accept multiple receivers until PAL is turned off, or will prefer to watch PAL broadcasts on the new upgraded display where program content differs between PAL and DTTB. (Note the Government emphasis on simulcasting.)

Any changes to the design used by larger markets will add to the cost of receivers and potentially slow the uptake. It is unlikely that there will be no change at all. Rather, it will be a matter of how little change, and the likely cost implications of specific changes.

The ability of the system receivers to cope with future system upgrades may be important in ensuring a reasonable life expectancy for the DTTB system. Allowance may need to be structured into the initial system design to meet the upgrades.

Receiver lock-up time following a channel change may be affected by the system characteristics.

7 MHz channelling, particularly in Bands IV and V, is little used outside Australia.

Following the rationalisation of the selection criteria to be used for guidance in the recommendation, the selection panel discussed all items and addressed the relative importance of each element and group of elements. Time was provided for all members to consult with their respective organisations with a view to establishing the level of importance of the elements.

A scale of five was agreed for weighting the importance of each element. Given the differences in the philosophies of the organisations represented it, was expected that there would be some variation in the weighting applied by each of the Panel members. It was agreed that the final weighting values used would be a simple average of the members’ proposed values.

It was further agreed that as the weighting values only had relevance to Australia, they should not be generally disclosed.

The sheet used to derive the final assessment is shown in Annex [B]

The Panel agreed not to disclose the final values derived from their numerical assessment. It considered these to be specifically relevant to Australian broadcasting, and possibly open to misinterpretation if used out of full context. Instead, it was decided that a summary of the Panel’s deliberations should be reported in order to explain the reasons behind the final recommendation.

It was noted that the process being used was to provide guidance to the Panel for its determination of the recommendation. As such the scoring was similar to that used to score a boxing match, but it varied by applying the importance weighting to the final points allocated.

It is important to record that the Panel took into account the best information available to it, but in assessing the information placed more emphasis on demonstrated performance than on anticipated or possible future developments.

It had been hoped that the data available from the Australian tests, supported by the field test and theoretical performance data from overseas tests, would allow detailed assessment of the coverage potential of the two systems. In the time available, this proved not to be feasible. While ATSC had specific advantages in simple carrier to noise performance and impulse noise, DVB had shown advantages in environments with significant or complex multipath.

It was considered that thorough analysis would require detailed quantification of such elements, with the variations applied to detailed coverage analysis. Given the time constraints applicable, this level of analysis was not possible. The significant reliance on indoor antennas (up to 30% of households in some Australian markets, according to survey figures provided to FACTS) was an important factor for the Panel’s assessment.

The Panel’s assessment also had regard to the Australian approach to achievement of television coverage areas. This is based on moderate power main transmitters supported by networks of translators in the significant outlying areas. There is an average of 10 translators for each main transmitter.

The Panel noted the differences between ATSC and DVB with respect to C/N. It also considered the effect of ghosting on each system. It considered that ATSC may have an advantage for the outer service area with roof top antennas, but that the modifying effect of ghosting might reduce the margin, particularly in obstructed reception areas.

The performance of the two systems beyond the nominal "primary" coverage area is less certain from the data available. In the areas where the angle of arrival is low there are more areas with partially or fully obstructed reception. In Australia the use of masthead amplifiers is common in the outer service areas.

Given the policy direction of the Australian Government to ensure DTTB availability to all current PAL viewers, the Panel needed to address the coverage question from two aspects. The first related to the transition period, when non-interference to PAL would set a power limit on DTTB. The second related to the period after termination of the PAL service, when power levels could be increased to provide full coverage.

On balance, the Panel considered the differences to be marginal rather than substantial and did not indicate a preference for either system in respect to criteria 1.1 and 1.2.

The Panel considered this issue could be set aside during the initial assessment. It remained a substantial issue, given the high proportion of Australian viewers using set-top antennas, but further testing and analysis was needed before any objective differential assessment could be made. While there was satisfaction that the DVB-T system performed adequately, the ATSC system was yet to be fully tested. It was decided that if this factor were potentially decisive in determining the choice the need for further testing would be addressed, even if that required a delay in the decision. However, in finalising the assessment, it was evident that the decision would not be affected by the results of further testing of indoor performance.

Mobile reception is not expected to be a major consideration for Australian television broadcasters. However, it was recognised that mobile broadcasting may have application for narrowcast (specific targeted audiences) and for datacasting. The latter is specifically addressed in Australian legislation to introduce DTTB.

The potential application of hierarchical coding for DVB was noted as a possibility to address mobile, but it was not known to be confirmed in practice. However the QPSK mode for DVB will allow compatible narrowcasting or data broadcasting services to be transmitted to buses, planes, etc.

The Panel noted this feature was not available in ATSC, though 2VSB modes had been suggested early in the US development.

Although this element was low on the weighting scale, DVB was preferred for this criterion.

The testing had demonstrated that DVB showed advantages in relation to interference between analogue and digital, while ATSC had an advantage in relation to non-coherent (i.e. unrelated program material) digital to digital interference.

Interference between analogue and digital will be important during the transition, while interference from digital may be important both during and after transition.

On balance, the Panel decided not to allocate a preference.

The Panel considered that both systems provided adequate performance.

The Panel considered that the tests showed this element was more adequately covered by the DVB system than ATSC, particularly for dynamic ghosts and complex ghosting in low signal strength areas.

The Panel considered that the ATSC system performed better than DVB in this parameter.

The Panel considered this issue was dependent on the way MATV systems were implemented. Many MATV systems use IF translation, while some more complex systems may use full demodulation and remodulation. The main domestic systems are either direct amplification or IF translation.

The Panel considered this issue could be left out of the current assessment because it was still an issue that had not been clearly resolved. Further investigation and testing would have been needed to provide any basis for realistic assessment.

The elements in this group mainly affect the practicality and cost of providing the infrastructure for broadcasting DTTB. For Australia, it is considered important that broadcasters are able to make maximum use of the existing transmission sites. Broadcasters also expect to rely heavily on the use of adjacent channels, for the dual advantage of reusing broadcaster and viewer antenna systems.

Additionally, the previously mentioned reliance on the use of translators contributed to the weighting factors agreed by the Panel.

The ATSC single carrier system is considered to be less tolerant to group delay errors within the channel than the DVB COFDM system. To some extent, this can be mitigated by using the full 7 MHz Australian channels to accommodate a 6 MHz ATSC signal. In a normal situation, a carefully positioned dynamic feedback sensor is required to drive the ATSC pre-correction system. In a typical Australian environment with multiple combined adjacent channels, appropriate positioning of the output sensing is made much more complex.

The Panel considered that this difficulty might be able to be compensated by fixed pre-correction of the combining and common antenna equipment. However, the large temperature variations that occur in many antenna systems with consequential changes to impedance were seen as posing a difficulty for fixed pre-correction.

It was accepted that the sensitivity of the ATSC system to group delay errors required feedback correction, and that this would be difficult in many cases. Because of the extensive use of common infrastructure and the proposed adjacent channel working in Australia, DVB was considered to have an advantage.

The Panel appreciated that work is taking place in the US to develop re-modulators for use in consumer products. When developed, this could allow use of demodulation and error corrected translators by using a consumer cost re-modulation.

While there was some discussion of the possibility for some sites to come down to baseband for possible Service Information data changes, this was seen as being an exception rather than the general case. For the majority of translators, DVB allows simple IF conversion, while the ATSC approach is yet to be developed.

It was agreed that DVB would have advantages on the basis of currently available technology.

The use of translators in Australia will generally involve reuse of translator frequencies within a single market, with the transmission content remaining the same. The co-channel advantage for ATSC is removed in such cases, and the coherent same channel capacity of DVB (SFN) becomes a useful tool.

DVB was considered to have an advantage for Australian requirements.

The Panel discussed the linearity requirements of both systems and the pre correction filter requirement in the ATSC system. On balance, both are expected to allow reuse of existing plant.

These criteria are considered to be important in meeting broadcasters’ and the Government’s service objectives for DTTB. Key objectives for the Government are for closed captioning and for HDTV. The Panel needed assurance that support would be available from DVB for HDTV, given the lack of enthusiasm for that service objective in Europe. Equally, the Panel needed to be sure that selection of the ATSC system would not restrict Australia to 60 Hz based standards.

Satisfactory assurances on the key elements were forthcoming from both parties.

The Panel noted that standards for HDTV had been set for both systems, and that equipment is available.

The Panel noted that closed captions were defined in the MPEG-2 transport stream.

The Panel also noted that DVB has a specific way of implementing closed captions and that the legislated requirement in the USA would ensure a similar capability in ATSC.

The Panel noted that the audio systems being developed for both systems would give enough flexibility to support multiple language audio channels by using additional elementary audio program streams.

There are different views on the relative performance quality of AC3 and MPEG-2 5.1 channel sound systems. On balance, AC3 was seen to have advantages, particularly bearing in mind the relative market penetration.

While not directly related to the Panel’s terms of reference, the operational implications of importing programs which have already been coded to 5.1 audio were discussed by the Panel. It was noted that consumer products are now using chipsets for decoding the 5.1 channel sound that can interpret either audio standard. As there are defined ways of accommodating AC3 in the MPEG-2 transport stream as well as MPEG-2 audio, it was considered that this subject could be addressed in the detailing of the final Australian standard, without differentiating between the systems.

Some elements in this category involved some conjecture about future development. The Panel’s considerations were based on their judgement of the best information available.

The Panel considered that while Europe had chosen not to go HDTV, the DVB system was capable of HDTV and had fully defined it in its standards during 1997. On the other hand, ATSC has founded its standards on delivery of HDTV. The Panel considered that both systems permitted any current HDTV standard to be used.

The Panel considered that both systems could operate adequately within the 7 MHz channel to provide appropriate service delivery and quality. It was considered that in this respect the 6 MHz mode of operation was needed for 8 VSB to ensure the adjacent channel and group delay performance could be maintained, but that any differences in performance were addressed in other specific criteria.

The assessment of this aspect involved consideration of the different structure of the two systems, with DVB having many operational modes available while ATSC is inherently fixed. Higher data rates are achievable for DVB (7 MHz) over ATSC (6 MHz) if reduced FEC and/or guard interval modes are used. On the other hand, there is a penalty in coverage for these higher bit rate modes. On balance the Panel felt that the modes used for the field tests offered the best comparative performance for the overall evaluation. In this respect there is little difference between the systems in terms of bit rate capacity.

The Panel was not aware of any significance in the overall delay beyond that inherent in the MPEG-2 encoding and decoding. As this aspect is common, there was no basis for differentiation between the two systems.

Advice to the Panel had indicated that 8VSB might be close to its theoretical capability, while DVB may have some room for further improvement. On the other hand, there is the expectation of improvements in the multipath performance for ATSC receivers over that tested.

It was considered that many of the desired features in each system were matters of conjecture at this time. An important factor determining development will be market acceptance, and this would not be known for some time. The commitment of USA to ATSC and consequent investment in improving the technology could balance DVB-T’s current advantage of apparent flexibility.

It was concluded that further development could be expected for both systems.

This group of criteria addressed elements relating to the availability of suitable receivers for the Australian market. In addition to general assurances by both ATSC and DVB that receivers would be available, the Panel sought advice from receiver manufacturers. Given the highly competitive nature of the consumer manufacturing industry, information on specific marketing plans and development of receivers was not expected, but generalised indications were received from some manufacturers. All responses indicated intentions to supply the Australian market irrespective of the system chosen.

It was also clear from information on VLSI developments that several manufacturers will have chip sets available for production of receivers for either system.

The Panel discussed the availability of receivers and agreed that international developments by chip and receiver manufacturers indicated that receivers would be available for both systems. All responses from receiver industry had indicated intentions to supply either system. Indications were that the choice of either modulation system would have minimal impact on cost, given that the display section of the receiver accounts for the bulk of the manufacturing cost.

Both systems have this capability.

After considerable discussion, it was concluded that whatever the outcome the receiver used for Australia will provide both PAL and DTTB if market demand is there.

The Panel considered that both systems would need to be specifically tailored for some Australian requirements. 7 MHz channelling in both VHF and UHF is one example. The level of specific design for Australia is not clear pending further detailed work on developing the Australian DTTB standards. The differences are likely to be in the lower cost parts of the receiver and, in any event, mainly in receiver aspects not directly associated with the choice of the DTTB system.

The Panel considered that both systems covered this issue adequately.

The Panel noted that part of the lock-up would relate to refreshing of the EPG’s. It will be determined more by decisions on the Service Information tables than by the choice of the modulation system. While there are differences between the service information structures being developed for the DVB set of standards and those associated with ATSC, the differences relate more to software, which was capable of being tailored to meet the Australian requirements.

It was decided this issue could be left out of the current assessment, although it remained a major issue to be resolved in the detailed development of the Australian standard

The Panel did not have much detailed information available, but based on its knowledge of the various options for channel selection it saw no significant difference between the systems. Whichever selection was chosen, there would be differences from the "native" market. Most European countries use 8 MHz spacing in UHF while all USA channel spacing is 6 MHz. In Australia, all channels will be 7 MHz spaced.

Based on the assessment of all criteria, related to the agreed weighting factors, the DTTB Selection Panel found a clear indication in favour of DVB. It further noted that even if the further testing of indoor reception indicated preference for ATSC, the over all assessment would still lead to DVB, based on the assessments and the weighting factors applied to the respective criteria.

The Recommendation was announced by a press release, which can be found at Annex A.

The Digital Terrestrial Television Broadcasting (DTTB) Selection Panel unanimously agreed today to recommend DVB-T for use in terrestrial over-the-air broadcasting in Australia.

The Selection Panel was comprised of members representing the National broadcasters (ABC and SBS), Commercial Network and Regional broadcasters, the Department of Communications, the Information Economy and the Arts, and the Australian Broadcasting Authority.

The Chairman of the Selection Panel, Bruce Robertson of the Nine Network, hailed the decision as an important milestone in establishing a framework for the introduction of digital broadcasting in 2001. He said that with this decision, the path was now clear for the industry to develop the full set of standards that will be needed for receivers to be designed in time to meet the start of digital television.

He added that the decision was important to broadcasters as they needed to start detailed planning for the change to digital and would have to order equipment in the near future to meet the 2001 deadline.

The decision follows a detailed evaluation of the two alternative digital systems over the past two years. This evaluation showed that both systems offered a viable choice for Australia, with each system offering competitive advantages.

The most important criteria in the overall assessment were to meet the coverage requirements foreshadowed in the draft legislation and to ensure the availability of receivers to match the high definition broadcasting intentions of the Government and broadcasters. The Australian tests satisfied the Panel that both systems met the basic coverage requirements.

Responses from receiver manufacturers have assured the Panel that there will be receivers available for high definition television in the chosen format.

With these basic requirements being satisfied, the Panel was able to concentrate its deliberations on elements of difference between the systems which will ensure the best outcome for the Australian broadcasting environment.

The recommendation will now be forwarded to the Department of Communications, Information Economy and the Arts for its formal ratification and to Standards Australia for formal documentation and public comment. The detailed standards will involve considerable work addressing the individual elements needed to define the interoperability, specific format details and service information elements needed for completed definition of the system to be used for Australia.

The Chairman said this decision reflected the results of considerable work by Australian experts and enormous cooperation from the ATSC and DVB organisations.

For further information:

Tony Branigan: Tel: (02) 9960-2622 (FACTS)

Bruce Robertson: Tel: (02) 9906-9999 (Nine Network Australia)

Dick Barton: Tel: (02) 9960-2622 (FACTS)

(Background attached - one page)

Since 1992 Australians have been active in studies and development of technology for the introduction of digital terrestrial television broadcasting.

By 1996 two main terrestrial systems had emerged as contenders for terrestrial broadcasting. The DVB system was developed in Europe while an alternative ATSC system was adopted for North America. Both systems are founded on the MPEG-2 digital compression standards and thus have a high degree of commonality. The main difference lies in the chosen modulation systems. ATSC uses a single carrier vestigial sideband modulation (8VSB) while DVB uses multiple carrier modulation-coded orthogonal frequency division multiplex (COFDM).

During 1996 and 1997, Bruce Robertson as Chairman of the FACTS Specialist Group-Advanced Transmission, was instrumental in arranging for the testing of both systems in Australia on an objective comparative basis. These tests were the first direct side-by-side comparison of the two systems conducted in the world. The tests formed the basis for making the most appropriate choice to fit the Australian broadcast environment.

The tests demonstrated that both systems have the capacity to meet the main objectives for a digital television service for Australia. The Selection Panel determined a set of selection criteria which addressed those differences in performance which might provide the better outcome for Australian broadcasters and viewers.

From an initial list of some 50 separate items, a final set of 29 criteria was identified as addressing relevant differences between the two contending systems.

Close contact was maintained with both ATSC and DVB throughout the testing and evaluation process to ensure the validity of the tests and the other relevant information needed for the full evaluation. Both organisations were extremely cooperative and helpful in meeting the requests.

Among the criteria assessed, the greatest weight was given to the ability to match existing coverage and to provide satisfactory interoperability with both the present analogue and other digital broadcasting services. Consumer products, and the availability of receivers capable of receiving a high definition service were also important factors. After ratification of the decision by the Department, full development of the detailed standards for Australian DTTB will now be progressed through industry and Standards Australia committees. Draft standards are expected to be completed before the end of 1998.

The final decision was taken unanimously. The Selection Panel acknowledged that each system demonstrated advantages over the others in particular aspects. The Selection Panel recommendation was based on the best overall fit to the specific requirements of Australian television broadcasting.