Digital Broadcasting
Digital Television
GENERAL
What is the difference between digital and analog television?
What are the benefits to consumers of digital television?
Why is the Government making these decisions now?
EXISTING FREE-TO-AIR BROADCASTERS
Is 7MHz of spectrum for broadcasters too much?
Is there any guarantee that existing free to air broadcasters will use spectrum for HDTV?
How can existing broadcasters use the 7MHz of spectrum?
SPECTRUM AVAILABILITY AND ALLOCATION
How much spectrum will be available for new players once existing players are allocated spectrum?
NEW BROADCASTING PLAYERS
When will the Government allow new broadcast players into the market?
DATACASTING
What sort of datacasting services will be available?
Will existing FTAs be charged for spectrum used for datacasting?
RECEIVING DIGITAL AND ANALOG TELEVISION
What will the Government do to ensure common standards for digital receivers and set-top boxes?
DIGITAL TELEVISION IN REGIONAL AREAS
How will the Government assist regional broadcasters to make that transition?
CONTENT
What sort of programs will be available on digital television?
How much Australian programming will be available?
Will additional services be provided for deaf and hearing impaired Australians?
FURTHER WORK REQUIRED
NATIONAL BROADCASTERS (THE ABC AND THE SBS)
COMMUNITY TELEVISION
Digital radio
What are the benefits to consumers of digital radio?
What will be the costs to consumers?
Why has the Government taken a different approach to digital radio than for digital television?
When will digital radio be introduced?
Why will radio stations be allocated only a share of multiplex transmission facilities?
General
What is the difference between digital and analog television?
Analog and digital television differ in the way the information is carried from the source to the receiver. In simple terms, in analog broadcasting the signal is in the form of a continuous wave form whereas a digital signal is in the form of discrete bits of information. The advantages of digital lie in the possibility of manipulating the bits of information in certain ways, so that information can be processed by both sender and receiver, can be compressed into smaller packages (hence using the available carrying capacity more efficiently) and the desired information can be more easily separated from the background noise and interference (hence resulting in clearer reception). The ability to compress the digital data stream means that digital transmission is far more efficient in its use of spectrum than analog transmission. What are the benefits to consumers of digital television?
The benefits of digital terrestrial television to viewers are substantial. Digital television allows the broadcast of widescreen, cinema quality programs with surround sound. It can also allow the provision of multiple information streams allowing the user access to a more enriching and even interactive television experience. From a technical point of view, it provides clearer, sharper pictures without the interference and ghosting that currently affect many viewers in built-up areas or hilly terrain. The change to digital is also being driven by adoption of digital television in other countries. The UK and the US are in the process of migrating to digital television, and a number of other countries are developing digital TV strategies. Increasingly, programs sourced from these markets (which comprise a substantial proportion of those broadcast on Australian networks) will be in digital format.
To take advantage of the benefits provided by digital television, consumers will be required to purchase either a new digital television set, or a set top box to convert the incoming digital signal for display on an analog receiver. It is difficult to predict how much sets will cost, and the price could fall rapidly once the market is established. Large widescreen digital sets capable of displaying high definition video will probably cost several thousand dollars, while conventionally sized sets are likely to approach the prices of current sets. The price of set top boxes will depend on their functionality, but will probably be a few hundred dollars. The simulcast period of at least 8 years (see briefing below) will ensure that viewers have plenty of time to plan the purchase of digital technology. Why is the Government making these decisions now?
Decisions by Government are required now to allow planning and capital investment to proceed and ensure that digital television becomes a reality within the next few years. Delays by Government in taking these decisions will result in continuing uncertainty for broadcasters and consumers and ultimately see Australia fall behind the rest of the world in the transition to digital broadcasting. Major broadcasting markets including the US and UK, from which a substantial proportion of the programs shown on Australian television are obtained, have already announced the implementation of digital TV.
EXISTING FREE-TO-AIR BROADCASTERS
Existing free to air television broadcasters will be loaned spectrum on condition that they use the spectrum to transmit a minimum level of HDTV, continue to simulcast their programs on their analog channels and return loaned spectrum at the end of the simulcast period. They will continue to pay the Government licence fees for their analog transmission based on their annual earnings. In 1996-97 this amounted to around $190 million. The provision of 7 MHz reflects the fact that the broadcast spectrum is organised into bands which are 7 MHz wide (as this is the amount currently needed to deliver PAL television). Broadcasters will be allocated channels not currently used for analog broadcasting. The provision of a full 7 MHz channel will also allow the broadcasters to deliver high definition TV (HDTV)-the widescreen, cinema quality television that digital broadcasting promises. The Government's decision to loan spectrum to the existing broadcasters for a simulcast period recognises that they will be required to make a very significant investment in the conversion to digital broadcasting (FACTS estimates around $500 million) in the face of uncertain consumer demand and advertising revenue, and at a time when they face increasing competition for viewer attention from new media such as the Internet. The broadcasters will also have to maintain separate infrastructure for both digital and analog transmission during the simulcast period.
Is 7MHz of spectrum for broadcasters too much?
It has been suggested that 7 MHz is too much, and that broadcasters can deliver television services using less spectrum (hence freeing up spectrum for other uses and other players). While digital technologies allow good quality television broadcasts using smaller bands, they would not allow HDTV - and broadcasters would be stopped from providing this application. It is also questionable how commercially attractive the remaining small bands of spectrum would be to other players. In any case, other full 7 MHz channels are available in most areas, which will not be required for digital television. These could be made available for other non-broadcast purposes, such as datacasting.
There will be a statutory requirement that digital television services commence by 1 January 2001 in metropolitan areas, and in regional areas from that date onwards so that all areas have services by 1 January 2004. Importantly, if FTAs fail to commence digital television services by the designated start-up date, they will be required to return the loaned spectrum to the Commonwealth. Broadcasters will also be required to submit to, and comply with, implementation plans approved by the Australian Broadcasting Authority.
Is there any guarantee that existing free to air broadcasters will use spectrum for HDTV?
FTAs will be required, by legislation, to commence broadcasting in HDTV from a specified date after the start-up of digital television services. However, there will be nothing to prevent FTAs commencing HDTV services prior to that date. Legislation will also require free to air television broadcasters to transmit a minimum proportion of their programs in HDTV format, which will increase over time. If the FTAs do not comply with the HDTV requirements, their loaned spectrum will be returned, in whole or in part, to the Commonwealth. This will ensure that spectrum loaned to the broadcasters will be used to provide consumers with the greatly enhanced viewing experience of HDTV. Details of the HDTV requirements will be announced following consultation with the broadcasting industry.
How can existing broadcasters use the 7MHz of spectrum?
The 7 MHz of spectrum can be thought of as a pipe which can carry a certain amount of data (the television signal). Digital technology allows the broadcaster to use the pipe in several different ways. For example, it can be all used to carry a single large volume of one kind of data, or it can be subdivided into several smaller pipes each carrying a smaller volume of a different kind of data. Different types of programming will result in different volumes of data: for example a high action sports program will use a larger volume of data than a 'talking heads' program. To provide high definition television, the broadcaster will need the whole pipe - HDTV needs a large continuous volume of information. FTAs will also be allowed to provide 'enhanced programming', where data capacity is used to provide enhancements to the main program stream. This could include features such as viewer-initiated multiple views of sporting events; for example, the pit-stop view and a trackside view during a motor race. FTAs may also provide other advanced information services which are linked to television programs (for example, viewer-initiated access to text-based or visual player profiles during a sports program) as well as direct terrestrial access to Internet-type services. Existing FTAs will be charged fees for datacasting services (see 'datacasting' below). Moreover, existing broadcasters can manage the flow down the pipe in a dynamic way, and will be able to switch from HDTV, to SDTV with program enhancements and back again as needed.
Free to air broadcasters will be able to provide enhancements directly linked to programs simulcast on the analog television channel and to use spare capacity to provide datacasting services. However, they will not be able use digital spectrum to provide pay TV or multi-channel services. These services are not part of their core business, and allowing them would put at substantial risk the viability of the fledgling subscription television industry. The Government will review this decision in 2005, to determine whether multichannelling and pay TV should be allowed by commercial FTAs having regard to developments in the pay TV industry. Prior to the introduction of DTTB, the Government will review whether the ABC and SBS should be allowed to broadcast multichannel programming which is non-commercial and is in line with their Charter obligations.
Spectrum Availability and Allocation
An open bidding process for broadcasting spectrum would create a highly uncertain environment for investment, as no existing broadcaster would be guaranteed spectrum. Essentially, this would amount to taking away the fundamental resource on which broadcasting companies survive and making it available to the highest bidder. Broadcasters who did not manage to obtain spectrum in the auction process would be unlikely to survive in the digital age, and consumers would not be guaranteed a good television service. Broadcasters already face many challenges in the conversion to digital broadcasting, including uncertainty about consumer demand for different services, and consumer takeup rates of equipment. An open bidding process could substantially undermine a smooth transition process. The uncertainty would also undermine long term programming and advertising commitments, and consumers could face the prospect of fewer services and less competition in the industry. In neither the US or the UK did the allocation of digital spectrum involve a price-based auction. How much spectrum will be available for new players once existing players are allocated spectrum?
The planning of the broadcasting spectrum currently provides for twelve 7 MHz channels (Channels 0-12) and two 6 MHz channels (Channels 5A and 9A) in the VHF bands, and forty two 7 MHz channels (Channels 28-69) in the UHF bands. The usage of channels varies from area to area, and has to be carefully planned to minimise interference between signals. Analog television signals cannot be placed in adjacent channels because of interference (hence, for example, the use of Channel 7 and Channel 9 leaving Channel 8 unused in between). The vacant 'protecting' channels are known as guard bands. In any broadcast area, each of the broadcasters has a main transmission site operating in a particular channel (eg the ABC in Channel 2). These are usually augmented by a number of secondary, lower powered transmitters, called translators, designed to extend the transmission or fill in poor reception areas. Translators operate on different bands from the main transmission. Thus, in a large urban area such as Sydney, with five channels and several translators, a large proportion of the available spectrum is used or unavailable due to interference. However, an important characteristic of digital television is that signals can be transmitted in the guardbands without interfering excessively with the analog signals in adjacent channels. This means that digital broadcasting can use the available spectrum much more efficiently. Digital signals can also be made to fit into the 6 MHz VHF channels which are not wide enough for analog broadcasts. The result is that even after providing each broadcaster with a second channel for digital broadcasting, there is spare capacity in virtually all areas of Australia which would be available for reallocation for other users. The precise channels available will vary from area to area. The Government will establish a technical committee to identify spare spectrum in the broadcast frequencies, which will then be made available for other non-broadcast purposes through a price-based allocation process. When will the Government allow new broadcast players into the market?
The current prohibition on the fourth licence will be extended until 31 December 2008.
A review will be conducted in 2005 into whether new commercial entrants be allowed
after 2008.Australia is well served by the current commercial television arrangements. The range of programming available to Australian audiences on free to air television is substantial and of high quality, with significant levels of Australian content. A fourth commercial channel would undermine the available advertising revenue base and thus the commercial viability of the existing three players particularly during the expensive conversion process to digital. Lifting the three licence restriction could result in negative consequences for the existing commercial television industry, without any significant offsetting benefits for the community. It is also questionable whether a fourth commercial broadcaster could provide sufficient quality Australian programming. Datacasting
Datacasting is a term which can be used to describe the transmission of data using the radiofrequency spectrum. In the context of broadcasting, it is normal to distinguish between the 'main' broadcasting signal comprising the normal television programs, and a datacasting signal providing other sorts of information, which could include text, still pictures, sounds and some video. There is nothing new about using wireless transmissions to provide data services. For example, the delivery of the Internet using wireless methods, including satellite and microwave, is becoming increasingly common. However, what the use of broadcasting spectrum offers is the ability to develop services which can be picked up in any home which has a television set, an appropriate set-top box and a standard antenna.
What sort of datacasting services will be available?
It will be up to the industry to develop datacasting services which are attractive to consumers. Preliminary indications from industry are that the 'first cabs off the rank' are likely to be services which involve providing suites of commonly used information such as weather reports, news, stock prices and entertainment guides, which are stored in users' sets or set top boxes and updated automatically several times a day. Other ideas involve the integration of Internet sites with television programming to allow users to (for example) obtain background information to a live sporting event off the Internet while viewing it (although the datacasting service only provides for information download, and for full Internet connectivity a return channel will be required (eg using a modem and telephone line)) The Government will conduct a review, prior to the introduction of digital television services, to determine further the television datacasting services to be allowed. At that time, the Government will also consider any possible legislative amendments required to respond to the increasing convergence between broadcasting and non-broadcasting services.
Will existing FTAs be charged for spectrum used for datacasting?
While the Government will not allow multichannelling, it will allow existing broadcasters to use (or sell) any spare capacity they have whilst transmitting their normal television programming to provide data services. However, they will be charged for the use of (otherwise free) spectrum for such purposes. Charging mechanisms will ensure that there is a level playing field between FTA and non-FTA datacasting providers (that is, that existing FTAs are charged an equivalent price to that paid on a competitive basis for unused spectrum). In addition, spectrum not required for digital conversion by the FTAs will be allocated on a competitive basis to new datacasting players.
The Government will require that a Planning and Steering Committee for digital terrestrial television be established to commence detailed technical planning and to identify broadcasting spectrum not required for digital conversion of existing free to air broadcasters. In addition, the Australian Communications Authority (ACA) and the ABA will be required to report on the structure of, and conditions for, the allocation of spectrum not required for the digital conversion of FTAs (the television datacasting spectrum). A fees regime for datacasting spectrum will also be developed which ensures a level playing field between FTA and non-FTA datacasting providers. Conditions of spectrum sale will preclude existing free to air broadcasters from bidding for this spectrum and ensure spectrum access, free of charge, of a standard definition community television service will be ensured. Unused spectrum identified in the review will be allocated on a competitive basis (and subject to conditions including those above) for television datacasting services in time for services to commence at the same time as free to air digital television broadcasting.
Receiving digital and analog television
There are different transmission characteristics of analog and digital television signals: - In analog broadcasting, there is a steady decline in reception quality the further the TV set is from the broadcast tower. People towards the edge of the reception area will get relatively poor quality TV, but there is no clear cut off point, meaning that people on the fringes will probably get some reception.
- In digital broadcasting, people throughout the reception area will get good quality reception which will change very little with distance from the broadcast tower. However, there comes a point at which reception fails, beyond which people get no reception at all.
- These characteristics will necessitate careful assessment and planning, area by area, to ensure that the maximum desired or achievable coverage is attained.
- In addition, broadcasters will be required to submit to, and comply with, implementation plans provided to the ABA for each area in Australia-including a timetable for digital commencement and a commitment to maintaining viewer coverage.
- The Government is committed to ensuring that people in regional Australia currently receiving analog television services will have access to a digital service of at least equivalent coverage and quality.
An adequate simulcasting period-during which analog services are broadcast alongside digital services-is required to ensure that new services can be rolled out, consumers have time to upgrade equipment, and for key issues to be reviewed as the picture for digital TV in Australia and overseas becomes clearer. The Government has specified that a simulcasting period of 8 years will be required. The Government has also made provisions for that period to be adjusted through regulations depending on needs of particular areas, and consumer takeup factors. Consumers have plenty of time to plan the upgrade to digital equipment. During the simulcast period consumers will still receive the current analog service on their existing sets or could choose to upgrade to digital equipment. When the simulcast period finishes consumers could choose to purchase a new, fully digital television receiver, or a set-top box which will allow them to receive digital signals on their analog sets.
Wherever possible, FTAs will be able to co-locate their digital transmitters at current analog sites. This will maximise the use of existing transmission infrastructure. The Government will also establish an access regime to allow existing FTAs reasonable access to transmission facilities for the purposes of installing digital transmitters. Actual requirements for transmission will be determined as part of a detailed technical planning process. The Government will establish a Planning and Steering Committee to conduct this process.
What will the Government do to ensure common standards for digital receivers and set-top boxes?
There are a broad range of technical issues on which future decisions will be required by government and industry as technology develops. Internationally, there is ongoing debate as to the appropriate standards to be used for digital television. Similarly, there is international recognition of the need to provide compatible technology for set-top boxes to enable navigation through free-to-air, pay TV, data or other services and ensure consumer convenience. The development of standards and compatible equipment is a matter for industry. However, the proposed Planning and Steering Committee will be required to consider the implications for Australian consumers of developments in this area. Digital Television in Regional Areas
The Government is committed to ensuring that people in regional Australia currently receiving analog television services have access to digital television services of at least equivalent coverage and quality. A careful, and realistic technical planning and implementation process will be undertaken to achieve this objective. The Government will establish a Digital Television Planning and Steering Committee to undertake detailed technical planning. In addition, regional broadcasters will be required to submit to, and comply with, implementation plans provided to the ABA for each area in Australia-including a timetable for digital commencement and a commitment to maintaining viewer coverage.
How will the Government assist regional broadcasters to make that transition?
The Government has indicated that digital services would be introduced from 2001 in regional areas with all areas receiving services by January 2004 (in accordance with a progressive build schedule). The Government will assist regional broadcasters' transition to digital through the allocation of additional spectrum, free of charge, for simulcasting their analog and digital services. In addition, no new broadcasting entrants will be allowed in the medium term, which could have posed particular threats to regional broadcasters at a time where significant capital investment was required by them for digital conversion. The Government will also consider whether additional support to regional broadcasters (such as licence rebates) is required when planning is complete and costs of transition to digital are known. Content
What sort of programs will be available on digital television?
Digital technology has been increasingly used in film and television production in the last decade. This means that there is already capacity to fully produce some programming digitally (for example, 60 Minutes, Race Around the World), as well as the technology to convert most analog programming to digital. Internationally, programs are increasingly being shot and post-produced digitally and this will, in the longer term, be the norm. It will be up to the broadcasters to convince consumers of the benefits of converting to digital television. This is most likely to be achieved through innovative programming as well as improved technical quality.
How much Australian programming will be available?
The Government is committed to ensuring that Australian audiences have access to a diverse range of Australian programming on commercial television. Therefore, the current Australian content standards-applicable to analog broadcasting-will also apply to digital television broadcasting.
Will additional services be provided for deaf and hearing impaired Australians?
The Government has been concerned that appropriate measures should be set in place to ensure that deaf and hearing impaired television viewers are not severely disadvantaged in any future digital television environment. The Government will require that broadcasters provide closed captioning for prime time viewing and for news and current affairs outside prime time. The Government considers that the provision of closed captioning for prime time broadcasts is a reasonable demand given that FTAs are being 'loaned' free spectrum. Further work required
The Government has provided a comprehensive and flexible framework to allow the introduction of digital TV. However, detailed regulatory issues will need to be examined prior to the introduction of digital television services, taking into account the evolving commercial applications, changing consumer preferences and technological developments. Accordingly the Government will set in place a number of processes to be undertaken before and during the simulcast phase. The Government will establish a Digital Television Planning and Steering Committee to: - advise on transmission standards and compatibility requirement (including issues related to conditional access systems);
- commence detailed technical planning; and
- identify broadcasting spectrum not required for the digital conversion of the FTAs.
- In addition, the ACA in consultation with the ABA will report on the structure of, and conditions for, the allocation of spectrum not required for the digital conversion of FTAs (the television datacasting spectrum). A fees regime for datacasting spectrum will also be developed which ensures a level playing field between FTA and non-FTA datacasting providers.
- Prior to the introduction of digital television, the Government will also review:
- the kinds of datacasting and enhanced programming (multiview) services which should be allowed;
- how legislation can be amended to reflect the growing convergence between broadcasting and other kinds of media and communications services;
- whether the national broadcasters should be allowed to transmit multi-channel programming which is non-commercial and in line with their Charter obligations; and
- rules for governing the retransmission of FTA digital services on pay TV systems.
- In 2005, the Government will review whether:
- new commercial FTA entrants should be allowed after 31 December 2008;
- commercial FTAs should be allowed to provide multi-channel and /or pay TV services using digital technology; and
- a simulcasting period other than 8 years should be prescribed in regulations.
National Broadcasters (The ABC and the SBS)
The ABC and the SBS will continue to play an important role in Australia's television future following the Government's announcements on digital television. The Government will provide a full 7MHz of spectrum to each of the national broadcasters, free of charge, to simulcast their analog and digital services. This will provide potential for HDTV programming which may be particularly well-suited to the programming mix of the national broadcasters (such as documentaries, feature films and arts programs). The ABC and the SBS will be subject to the general prohibition on provision of multichannel services. However, the Government recognises that there may be benefits-particularly to regional viewers-of the national broadcasters undertaking multi-channel services which are non-commercial and are linked to their specific Charter obligations. The Government will review whether the ABC and SBS should be allowed to multi-channel such programming prior to the introduction of digital television. The ABC and the SBS will also be allowed to use (or lease out) residual capacity to provide commercial datacasting services. These services could range from advanced information services linked to programs to direct terrestrial access to Internet-type services. Revenue raised from these activities will be subject to an appropriate revenue sharing agreement with the Commonwealth, in line with competitive neutrality principles. The Government is currently examining the national broadcasters' future funding requirements for the transition to the digital environment. Community Television
The Government will assist the migration of community television to the digital environment by requiring new datacasting players to ensure spectrum access, free of charge, of a standard definition community television service as a condition of their licence. The Government also recognises the vulnerability of the community television sector and that it faces considerable challenges in funding its own migration to digital transmission. The Government will also consider, in light of its other fiscal priorities, whether revenue obtained from allocation of spectrum for commercial datacasting would also enable the Government to assist community TV broadcasters in meeting the upfront costs of digital conversion.
Digital radio
What are the benefits to consumers of digital radio?
Digital radio can: - deliver CD quality sound to fixed, portable and mobile receivers;
- provide for better reception than current AM and FM radio broadcasts; and
- requires far less spectrum than the current analog system.
What will be the costs to consumers?
Consumers will need to purchase new digital radio receivers to take full advantage of these benefits. It is difficult to predict how much sets will cost, and as with most new technology, these costs are likely to fall rapidly as the market is established in Australia and internationally. Consumers will also be able to continue to listen to their radio services on analog receivers during the simulcasting period.
Why has the Government taken a different approach to digital radio than for digital television?
The Government's approach to digital radio recognises that there are structural differences between the radio and television sectors-in particular the relatively large number of service providers in the radio industry. Detailed regulatory issues, such as arrangements for sharing of multiplex facilities, will be examined as part of the process of planning for the introduction of digital radio services.
When will digital radio be introduced?
Planning will proceed on the basis that digital radio will commence transmission at the same time as digital television services. The Government will establish a Digital Radio Planning and Steering Committee to report on technical planning issues and appropriate legislative amendments.
Why will radio stations be allocated only a share of multiplex transmission facilities?
One digital radio multiplex provides five CD quality services. There are a number of advantages in broadcasters sharing the multiplex facility: it allows broadcasters to share costs for establishing the multiplex; it ensures there is sufficient spectrum available in metropolitan markets and that new entrants can be accommodated; and ensures that broadcasters do not 'own' channels but do not use them.
It is likely that digital radio will be introduced in Australia using the Eureka 147 system (an international standard). This is the only terrestrial digital radio system which has, to date, been demonstrated to operate effectively, and offers a range of benefits to radio audiences, including higher quality sound, and more reliable reception, than AM and FM radio broadcasts. It is also likely that L-Band spectrum will be used for digital radio transmission (with some use of VHF spectrum in regional areas). The Government is committed to ensuring the best possible outcome for consumers with the introduction of digital radio. In light of this, other planning options and transmission standards will not be discounted in the planning process.
Analog broadcasting
Conventional broadcasting, in which the picture, sound and other information is transmitted as a continuous wave form.
ATSC and DVB
The acronyms for the US and European formal standards for digital television.
- ATSC = Advanced Television Systems Committee (US)
- DVB = Digital Video Broadcasting (Europe)
The standards provide for a wide range of technical and other specifications for digital television broadcasting. They have many similarities - for example, both use the same compression system for the video signal. The most significant difference is in the modulation system adopted for the radiofrequency signal carrying the information.
Compression
A process whereby the digital signal is 'squashed' to fit a particular transmission capacity, by various mathematical processes.
Datacasting
An imprecise expression to cover the range of possible data services which could be delivered using the available transmission capacity, but not including the main broadcasting program stream(s).
Digital broadcasting
Broadcasting in which picture and other information is converted into, and transmitted as, a series of discrete 'bits'.
High definition television (HDTV)
Television with approximately twice the resolution of SDTV. Various options of lines and pixels are provide for in standards, eg 1080 lines by approximately 1900 pixels, aspect ratio 16:9.
Multichannel
and
Enhanced program/multiview
Digital television enables a data transmission rate in excess of 20 MBits per second using a 7 MHz channel. SDTV requires around 8 MBits per second to achieve good picture quality, and less for low quality. HDTV requires the full available transmission rate. Thus, a broadcaster has the option of providing
- one channel of HDTV
- three or more entirely separate channels of programming at SDTV (multichannelling)
- enhanced views of the same program eg different camera angles on an event (enhanced programming or multiview)
Radiofrequency spectrum
A discrete part of the spectrum, which is used for various radio communications.
- The radiofrequency spectrum is labelled according to the frequency of the radio waves in cycles per second (Hertz, Hz)
- The frequencies included are from 3kHz to 300GHz
- This spectrum is planned according to internationally agreed guidelines, so that particular parts of it are reserved for particular purposes. Television is allocated spectrum in the 45-230 MHz range (VHF) and 580-820 MHz range (UHF), which in Australia is divided into 7 MHz bands.
- Long wavelength areas of the spectrum have different characteristics from short wavelength areas - for example, shorter wavelengths usually have a shorter transmission range for a given power. This makes them useful for different purposes
Spectrum
A natural phenomenon comprising the continuous range of electromagnetic radiation ranging from the longest radio waves (with wavelengths measured in many metres) through infrared, visible light, ultra violet, X rays and gamma rays, where the wavelength is approaching the size of atoms. See radiofrequency spectrum.
Standard definition television (SDTV)
Television with the same format and definition as the current PAL analog system ie
- 625 lines vertically
- 720 dots (pixels) per line
- 50 frames per second using interlaced scanning
- aspect ratio (ratio of width to height of screen) 4:3.
Terrestrial broadcasting
Broadcasting from towers or masts using the radiofrequency spectrum (does not include satellite broadcasting and cable broadcasting).
Copyright © Commonwealth of Australia 1996 · Last update: Wednesday, 25-Mar-98
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