Digital Terrestrial Television

TERRESTRIAL TELEVISION “Digital television is a new television service representing the most significant development in television technology since the advent of color television. ” Studente: Francesco Gui (matr.

144187) Corso: Telecomunicazioni (a. a. 2009/2010) DIGITAL INDEX 1. Technology - The digital signal - Digital television types - Transmission scheme 2. Advantages & Disadvantages - Spectrum reallocation . No Ridondance .

Digital Dividend - Interaction - Other advantages - Disadvantages 3. Italian Transiction TECHNOLOGY: The digital signalDigital Terrestrial Television (DTTV or DTT) is the technological evolution and advance from analogue terrestrial television, which broadcasts land based (terrestrial) signals. Analog is a continuous waveform, with examples such as (naturally occurring) music and voice Digital is a discrete or non-continuous waveform with examples such as computer 1s and 0s (*see online course material, chapter 2) TECHNOLOGY: Digital television types Digital terrestrial Television (Free-to-air, Pay TV) Digital Satellitar Television Digital Cable Television Digital Mobile Television W eb Television (IPTV, P2p TV)The digital terrestrial tellevision (DTT) has more or less the same performances of analogue terrestrial television. This tecnology only needs users to buy a decoder as it uses the same infrastructures of analogue tv. DTT is divided in free-to-air television (gratis) and pay-tv (or premium), in this case you need to insert a rechargeable card in you decoder in order to see certain channels and transmission. Digital cable television (DCT) and Digital satellitar television (DST) are transmitted by coassial cable, ptical fibre or by satellite instead of classical aerials.

In these cases the transiction to digital television is easier as users already know they have to buy a decoder and how to use it. Digital mobile television (DMT) is provided by telephone companies which trasmit its signal by their telecomunication network. An appropriate cellular phone or palm is needed to receive and watch it. Web televion is the television transmitted on internet wires. It is visibile on the computer monitor or on the tv screen.There is also the possibility for private users to provide e trasmit Tv content (without any quality garancy).

TECHNOLOGY: Transmission scheme Due to the italian anti-trust laws Conent provider, Service provider and Network provider must be three diffrent subjects. The transmission network (infrastructures) is the same of the analogue televionsion. A Set-top box (decoder) is needed to decode the signal received and display channels. • A zapper is a decoder that only decodes signal (condittioned interaction) • A modern Set-top box also allow you to send back information.With the exceptions of coaxial and fiber optic cable, which can be bidirectional, a dialup modem, Internet connection, or other method is typically used for the return path with unidirectional networks such as satellite or antenna broadcast. TECHNOLOGY: Standards DVB-T (Digital Video Broadcasting-Terrestrial) The system has been designed to operate within the existing television devices - Standard definition videos: MPEG-2, MP@ML - High definition videos: MPEG-4, AVC; - Audio contents: MPEG-1, Layer II & Dolby Digital Multimedial & interactive contents: MHP (Java)There are diffrent modultaion method.

DVB-T is the encoding standard used in Europe, it adapts very well our existent infrastructures and aerials (so you can receive it like UHF or VHF channels without changing your aerial). This standard is mainly based on MPEG-4 format. MHP (Multimedial home platform) is the software that allows decoder to send informations and be interactive. Both DVB and MHP are open-standards so it is possible for everyone to see their formulas, use them and realize devices such as set-top boxes.ADVANTAGES: The Electromagnetic Spectrum ATT: more frequencies transmitting the same channel DTT: the same frequency (multiplex) transmitting more channels (1:5) Frequencies in the elctromagnetic spectrum have got diffren proprieties.

Television frequency realize a good trade-off between transmission power (waves ability to travel and propagate) and capacity of carrying data. But there is a limited number of frequencies of this type. Every channel (in analogue televion) needs at least 8 Mhz so the total number of possible channels is small.Digital television is able to transmit a larger amount of data (diffrent channels) on the same radio frequency (this technology is called multiplex), reallocating spectrum frequencies and solving the problem of its limitation ADVANTAGES: No ridondance Modulation: COFDM (coded orthogonal frequency division multiplexing) with either 64 or 16 state Quadrature Amplitude Modulation (QAM). Compression : (MPEG-2) Optical elaboration: consecutive lines, fast scenes Eliminating ridondance and useless part of the signal digital televison can trasmit a larger amount of data in tha same space (for example 8 Mhz).The amount of data that can be transmitted (and therefore the number of channels) is directly affected by the modulation method of the channel.

The modulation method in DVB-T is COFDM with either 64 or 16 state Quadrature Amplitude Modulation (QAM). In general a 64QAM channel is capable of transmitting a greater bitrate, but is more susceptible to interference. So it is possible to transmit more channels (for example 5 instead of 1) on the same radio frequency, and also trasmit radio, data and other services.ADVANTAGES: Digital dividend Digital dividend: the possibility, after the analogic switch off, to use a large amount of frequencies for different scopes (communication networks, mobile services, wireless and satellitar services, pubblic security or emergency.

.. ) The digital dividend is a term used to describe the benefits that arise from the conversion to digital television. But the term is not really about the benefits of digital television, such as clearer pictures, high definition, electronic program guides, etc.The term is used more in the sense that the switching off of analog television services will free up significant amounts of spectrum in the VHF and UHF bands, and that will open up opportunities to provide new services.

The size and nature of the digital dividend will depend on how a every government decides to use this spectrum. Possible uses of new digital frequencies are: • New mobile services, with high quality video and interactive media delivered to handheld devices. • Wireless broadband services, with high-speed data and voice services. Wider coverage for advanced services in remote and rural areas.

This spectrum is particularly suitable for low cost, wider-area coverage. • Advanced business and broadcasting services, such as those used to support major sporting events. • Additional television channels including possible High Definition (HD) channels carried on Freeview. • Pubblic security or emergency alarm system, specially in areas with high risk of floods or heartquakes ADVANTAGES: Interaction Conditionned interaction: Supertelex Games Guide, Menu & film info Real interaction: Quiz T-learning T-banking T-governement T-commerce T-WebConditionned Interaction: programs, games or sets of informations loaded on the decoder (zapper) and accessible with the remote control (using colored bottons) Real interaction: interaction between the end-user and the broadcaster through the use of a return path. T-Commerce: Possibility of buying product on-line chosing between a catalogue displayed on the tv screen T-Government: Interactive service that permit to connect to the pubblic amministration network in order to get informnations, documents, certificates etc..

T-Banking: Possiblity to connect to your bank and get informations, check your count or do bank operations T-Learning: Interactive method of learning in wich you can attend courses, see lessons or do exercise on your television. OTHER ADVANTAGES: - Reception tends to be better - Resolutions and sound fidelity - Specific targetted channels - Subchannels from the same broadcaster - The radio spectrum can be re-auctioned off by the government. - Telecommunications industries can introduce new services - Less electromagnetic pollutionFor the end-user, digital television has potential for resolutions and sound fidelity comparable with blu-ray home video and with digital multiplexing, it is also possible to offer subchannels, distinct simulcast programming, from the same broadcaster. For government and industry, digital television reallocates the radio spectrum so that can be auctioned off by the government. In the subsequent auctions, telecommunications industries can introduce new services and products in mobile telephony, wi-fi internet, and other nationwide telecommunications projects.Digital reception tends to be better overall, particularly with a good signal (It is easier to obtain the optimum digital picture than the optimum analogue picture).

With a weaker signal there is little perceptible difference, in fact analogue can be better. DISADVANTAGES: - New equipment required (Set-top box) - Increased electricity consumption - An upgraded antenna installation may be required. - Analogue requires lower signal strength to get a viewable picture = more potential users. with low signal strength an analogue picture gets fuzzy but is still viewable while a digital picture freezes and stops updating ) - Switching channels is slower (time delays in decoding digital signals) ITALY: Transiction Digital switch-over : intermediate phase of the process in whitch analog and digital televisions coexist (simulcast) Analog switch-off: analog television is switched off (12 dicember 2012 is the dead-line estabilished by European Union) “There is a fundamental opportunity offered by DTT.

It is the possibility to solve, once and for all, the problem of the quality of television content….With more channels available, there will be room for high cultural [channels] as well as for contents more in tune with mass interests. The TV system in its whole will guarantee that all interests representative of the culture of the country will receive the same treatment, will have the same dignity”. (Carlo Sartori) THE END OPEN ISSUES: – Will digital television rise the quality level of italian telvision? We are witnessing a tendency in which quality TV content is migrating to pay-TV, leaving programming of lower quality on free-to-air channels.

Will digital televsion solve the problem of the absence of pluralism in italian television? Gentiloni's plan and Gasparri law set some limits in order to reduce their market quote in digital television and favour the entrance of new subjects but in the italian history the problem of duopoly of RAI (pubblic service) and MEDIASET has never been solved. REFERENCES: MAIN SOURCES: www. aeranti. it www. dgtvi.

it www. digitaleterrestre. rai. it www. digitaltv.

gov. hk www. fub. it (Fondazione Ugo Bordoni) www.

javnost-thepublic. org www. ofcom. org www. wikipedia.

com