Analog to DigitalAnalog to Digital TV TV Transition Transition in the Republic in the Republic

of Serbiaof Serbia

Conference: Digitization of Conference: Digitization of National Heritage, National Heritage,

June 16June 16thth 20201010..

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

Optical to analogue image conversion

By scanning optical image, electrical signal is formed, as an exact replica of an optical image

Optical image

Output voltage

Scanned line

SkyTree

Sky Smoke

Branch

Electrical signal

Optical image

LineOutput voltage

Scanned line

Signal processing in digital technology consists of :

• Digitization (sampling, quantization) • Compression• Coding

Optical to digital image conversion

Electrical signal

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

NP 1

NP 7

RP 1

RP ≤7

MUXmaximum 14

programs

Distribution

• In one DVB-T2 MUX, maximum 14 SD programs

• Distribution: primary and secondary

DVB package

DVB package

Data

Audio 1

Audio 2

Video

Audio

Data

Teletext

Data

Data

Radio

Radio

TV

TV

SI Service Information

PSI Program Specific Information

•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

COFDM

time

frequency

OFDMOFDMsymbol

time

frequency

RF channel bandwidth

frequencysubband

timesegment

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

IP/MPLS networkIP/MPLS network

NHE

DVB-T2

DVB-T2

SDTV

RHE

Regional headend

RHE

RHE

NationalNational headend headend

milena.jocic@mtid.gov.rsmilena.jocic@mtid.gov.rs