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Conference: Digitization of National Heritage, June 16 th 20 10. Analog to Digital TV Transition in the Republic of Serbia. M.Sc.E.E. Milena Jocić Adviser, Department for Telecommunications Minist ry of Telecommunications and Information Society, Republic of Serbia. Television.
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Conference: Digitization of National Heritage, June 16th2010. Analog to DigitalTV Transition in the Republic of Serbia M.Sc.E.E. Milena Jocić Adviser, Department for Telecommunications Ministry of Telecommunications and Information Society, Republic of Serbia
Television • Commercially available since the late 1930s • Television is more than popular in Serbia: The average Serbian citizen spends approximately six hours a day watching TV! • Analog to digital TV transition we are discussing about: only for terrestrial platform!
Amazing thing about human brain that makes television possible: If a still image is divided into small dots, the brain will reassemble the dots into a meaningful image
Pixel On a TV screen, the small dots are called pixels (picture element)
Resolution (number of pixels) The most common resolutions of TV screen: • 768x576 pixels (SD), generally signal is broadcasted in 4:3 aspect ratio • 1920x1080 pixels (HD), broadcasted in 16:9 aspect ratio
Another amazing thing about human brain that makes television possible: If a moving scene is divided into a sequence of still pictures and if the still images are shown in rapid succession, the brain will reassemble the still images into a single, moving scene
It is possible because of HVS and HAS Human Visual System (HVS) – characteristics of the human visual system are not perfect and its disadvantages are used in video compression: Persistence of vision is a characteristic of the human eye - light that reaches the eye remains in our consciousness about a tenth of a second more Human Auditory System (HAS) - characteristics of the human auditory system are not perfect and its disadvantages are used in audio compression
Why going digital? • better picture and sound quality • variety of contents • more radio and television programs • new services for users with disabilities and for senior citizens • enhanced additional services • portable and mobile program reception • convergence of services
By scanning optical image, electrical signal is formed, as an exact replica of an optical image Electrical signal Optical image Output voltage Sky Sky Smoke Tree Branch Scanned line Optical to analogue image conversion
Output voltage Scanned line Optical to digital image conversion Optical image Electrical signal Line • Signal processing in digital technology consists of : • Digitization (sampling, quantization) • Compression• Coding
Why compression? Broadcasting of big amount of information requires a large bandwidth: • For analog TV - 5-6 MHz • For digital TV - minimum 10 times of the bandwidth for analog is needed • That is why data compression is used • Compression methods used in digital TV: MPEG-2 and MPEG-4 • Serbia has chosen MPEG-4
Multiplexing DVBpackage NP 1 MUX maximum 14 programs NP 7 Distribution RP 1 RP ≤7 • In one DVB-T2 MUX, maximum 14 SD programs • Distribution: primary and secondary
Radio Data Radio Data TV TV SI Service Information Video PSI Program Specific Information Audio Audio 1 Data Teletext Audio 2 Data DVB package • Box in which the data is stored
Why modulation? • Modulated signal requires less power to transmit and a smaller antenna due to the higher frequency of the carrier wave • In digital TV, digital modulations are used • Digital modulation: an analog carrier signal is modulated by a digital bit stream
Popular scheme for digital TV: COFDM • A large number of closely-spaced sub-carriers are used to carry data • Each sub-carrier is modulated with a conventional modulation scheme (such as QAM or PSK) at a low symbol rate, maintaining total data rates similar to conventional single-carrier modulation schemes in the same bandwidth
time time RF channel bandwidth frequency subband OFDM OFDM symbol frequency time segment frequency COFDM
Transmission standards in Europe: DVB-T and DVB-T2 • DVB-T is used all around Europe, but DVB-T2 is spreading fast
Serbia has chosen DVB-T2. Why? • DVB-T2 provides higher bit-rate within the same TV channel band, comparing to DVB-T • The owners of broadcasting equipment that use DVB-T2 standard will benefit: DVB-T2 supports many programs content within one multiplex • DVB-T2 is compatible with IPTV • Investments in the digitalization process in the Republic of Serbia demand a great deal of financial means. Switch to a different standard (from DVB-T to DVB-T2) would demand new investments • DVB-T2 secures sufficient bit-rate for the needs of many HDTV programs • The application of DVB-T2 standard significantly increases digital dividend
Switchover from analog to digital TV broadcasting • Serbia must switch-off the analog TV signal before 17th June 2015 • Recommendation of the EC to the EU member states: ASO until 2012 • Serbian decision: April 4th 2012!
Distribution network architecture Nationalheadend RHE DVB-T2 NHE IP/MPLS network Regional headend DVB-T2 RHE RHE