High definition image, digital sound, stable signal, interactivity, multiple channels, and the possibility of connecting to the Internet through the television are only a few of the advantages of Digital Television.
This image-capture and transmission system is already in operation in many countries and may become reality in Brazil within a couple of years.
In case everything works out, president Luiz Inácio Lula da Silva’s desire of watching the 2006 World Cup on Digital TV should come true.
The study for installation of this system in the country started in 1994 at the request of the Brazilian Association of Radio and Television Companies (Abert) and gained force in 1998, when the National Telecommunications Agency (Anatel), the telecommunications regulator in Brazil, started stimulating (laboratory and field) testing of the three existing digital land systems: the American (ATSC), the European (DVB-T) and the Japanese (ISDB-T).
Currently, 44 Brazilian universities are studying Digital TV and intend to join their work.
Transfer from the analog to the digital transmission system is not only technological evolution, but also the creation of a new communications platform for the country, capable of offering dozens of benefits to users and increase digital inclusion.
Eyeing this possibility, the Communications Ministry has determined that, whatever the Digital TV standard to be adopted in Brazil, it will have to be open and free, accessible to the population that is reached by analog TV, and capable of making internet connections, thus ending the digital exclusion.
Open television currently reaches over 80% of the homes in the country, but only 8.6% of them have access to the internet. There are over 140 million “digitally excluded” people in the country.”
Digital TV may revert this figure and provide 57 million analog televisions users – not counting their family members – with access to the world computer network.
Digital TV and HDTV
Despite being two completely different products, some people confuse Digital TV with high definition TV.
Digital TV is the transmission, reception and processing system of high definition signals, in digital format, which may be sent via satellite, microwave or cable.
High definition TV is a television model with image quality comparable to that of the cinema, and is prepared for Digital TV reception.
The Brazilian government and specialists in various sectors involved in Digital TV are discussing three possible strategies for implementation in the country.
The elaboration of a completely new Brazilian Digital TV system, the creation of a Brazilian standard only for interactivity (middleware), and the pure and simple use of one of the three existing international standards.
According to the specialists, whatever the decision, implementation of the system chosen will take, at least, two years.
Recently president Luiz Inácio Lula da Silva signed a decree establishing guidelines for the study and research of digital technology for radio broadcast services.
The document created the Executive Group for the Digital Television Program (Get), which will present studies and alternatives for implementation of the domestic digital system.
The digital system choice is only the first step of the Brazilian television digitalizing process.
In practice, implementation of all the phases, – transmission, production, distribution, and reception, which involves television channels, producers, and equipment makers – should take between 10 and 15 years.
During this period, digital and analog transmission will operate simultaneously, as is happening in telephony, where both systems currently coexist.
In future, all televisions will be digital, and analog televisions will only operate when connected to signal converters.
The current analog television land transmission system uses VHF (Very High Frequency) and UHF (Ultra High Frequency), which send brightness and hue information, and stereo or mono audio signals.
In Digital TV, the signal is compressed and is sent digitally, permitting the incorporation of a series of additional resources, such as high definition, multiple channels and digital sound, among others.
The possibility of transmitting high definition images, or HDTV (High Definition TV) is one of the main attractions of Digital TV. HDTV increases the resolution from 480 lines to 1,080 horizontal lines, improving captured image texture, color, and depth quality, improving sensation of reality in the scenes.
With it, it is also possible to send up to four video signals, permitting the simultaneous transmission of an event, for example, through four different angles.
The audio signal is also much better. The sound quality is similar to that of a CD and faithfully reproduces cinema movies recorded on the 5.1-channel Dolby Digital standard.
On digital TV, the signal is constant and uninterrupted, eliminating reception problems and the irritating shaky or ghost images.
And that is not all. Thanks to being interactive, Digital TV makes it possible for users to veto the exhibition of scenes considered inappropriate, or choose a language in which to watch a movie.
It will also be possible to connect to the Internet, access your bank account, buy products, and even participate in programs via the TV remote control.
Some of these advantages will only be available to the people who have high resolution TVs, which have around 2 million image points (pixels) against the 210,000 on conventional televisions.
But for those who don’t want to, or can’t buy a special Digital Ready television, use of a decoder, which permits digital reception on analog televisions, is a possibility.
The decoder (set top box) is similar to the model used by cable television services and receives the digital signal and converts it so that it may be seen on an analog television set.
It works like a DVD, which decodes the audio and video signals and transforms them into digital signals.
The use of a converter is another Communications Ministry determination so that users may continue using their current television sets for a reasonable period of time, without damaging analog reception.
The previous government defended the adoption of one of the three international Digital TV standards. Now the intention is to develop an individual system and use part of the currently existing technologies.
But there is still great argument about whether or not Brazil should create another system. To some specialists, the country does not need to reinvent the wheel so as to have access to the technology; to others, an individual standard would bring autonomy and money.
The only strategy that has been discarded is the so-called hybrid technology – mixing all three models into one product.
In the tests that have already been executed, using the three existing standards, emphasis was placed on the ISDB system, which presented operation flexibility and the potential for mobility (in vehicles) and portability (small receptors which may be used in movement or at a standstill).
The Japanese model is also better adapted to mobile telephony, and makes technological integration between both transmission systems easier. However, ISDB is the only system that has not yet been put into operation.
The ATSC standard has been in operation in the United States since 1998 and has already been adopted in Canada, South Korea, and Taiwan.
This system was developed for cable or satellite operation, and does not permit mobile reception. During the testing period, it also proved inefficient in land reception through an internal antenna.
DVB is already a reality in various countries in Europe, and permits reception on mobile terminals. Like the Japanese system, it uses the COFDM modulation system to protect the signal from interference and degradation.
Its satellite version – DVB-S – has already become an international standard for this kind of transmission, greatly used by cable TV operators.
In reality, cable television channels already offer many of the advantages and interactivity resources of the Digital TV system.
Implementation of the system in open television channels will make this technological more democratic, and will give any Brazilian owning a digital television set or an adapted analog television set access to it.
Specialists in the sector believe that the converter may be sold in Brazil for around US$ 50.
AB
