“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)
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 signal
Digital 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, optical 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.
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:...
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
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