digea

Welcome to the digital era!

Dictionary


Digital terrestrial television

The future of television. It is the method where the TV signal is transferred to our homes or anywhere with a TV receiver. The term terrestrial is used since the broadcasting technology is performed from land-based broadcasting centers [and not via satellite for example], while digital television refers to the type of television signal that reaches our homes and not the type of television or decoder technology that is available at home.

On a global scale, digital television replaces analogue TV at a rapid pace due to the deadline set [June 2015] by the International Telecommunication Union [I.T.U.] for the transition from analogue to digital TV.

In Greece, the digital technology is free to the audience for channels that broadcast their content free, having first received approval by the National Broadcasting Council [E.S.R. in Greek] for digital broadcasting of their analogue program.


Frequency map

Is the map based on which the digital terrestrial television network is developed.

It has been designed by the Ministry of Infrastructure, Transport and Networks in cooperation with the Minister of State and is included in the Joint Ministerial Decision 42800/5-10-2012, G.G. 2704/Β’/5-10-2012.

This map defines the 34 allotments that the country has been split into, the 156 broadcasting centers, the available frequencies, etc.


Allotment

An allotment is the geographical area which to which a specific number of channels has been assigned for the development of a Single Frequency Network [SFN]. For digital television in Greece, 34 allotments have been defined in total.


Single Frequency Network [SFN]

A network of synchronized broadcasting centers [stations] which transmit identical signals on the same radio channels [frequencies].

For example, for the digital coverage of one section of Attica, eight broadcasting centers [Hymettus, Parnitha, Aegina, Ochthonia, Prasino, Chalkida, Avlonas, Vari] create an SFN by broadcasting on the same frequencies and with equal parameters.


Switch-off

Ceasing of the analogue terrestrial television signal with simultaneous activation of the digital terrestrial signal.


Switchover

The transition process from analogue to digital television.


Nationwide television stations

Channels whose signal is broadcasted throughout the country.


Regional television stations

Channels whose signal is broadcasted in specific regions [boroughs].


 


Decoder / receiver

An electronic device for the decoding and playing of video and audio signals as well as MPEG data. When connected to an antenna [internal or external] it receives the signal and turns it into a signal compatible with television sets of older technology. In modern television sets the decoder is usually integrated within, however some [mainly older sets] may only support the MPEG-2 format and not the MPEG-4 signal.

The “decoder” is often confused with a “descrambler” [mainly in the market], although they are different devices.


Descrambler

Electronic device used for descrambling encrypted programs, usually subscription or pay-per-view channels.


 


Broadcasting center

The station from which the digital terrestrial television signal is broadcasted. Under current legislation, in Greece a total of 156 broadcasting centers [main stations] will be activated.


Gap filler

Also known as a local transponder, the gap filler is a small-powered digital terrestrial broadcasting station used for digital signal transmission in areas that receive no coverage from the broadcasting centers [main stations].


Multiplexer [MUX]

A device used for the simultaneous transmission of data from multiple sources within the same network bandwidth.

The multiplexer selects one or more digital low-speed signals, combines them and transports them with greater speed through a common data transmission channel, such as a copper cable or an optical fiber. In essence, the multiplexer acts as a converter of multiple incoming signals into one outgoing signal.


 


Digital Video Broadcasting - Terrestrial [DVB-T]

A standard for digital terrestrial television signal transmission. It uses the known from analogue broadcasting UHF and VHF channels and digital reception is land-based and achieved using antennas [aerials].


Ultra High Frequency [UHF]

An electromagnetic wave spectrum ranging from 300 MHz to 3 GHz [3000 MHz]. It is mainly used for telecasts, mobile telephones, amateur transmissions, Wi-fi, special radio networks, etc.


Channel / frequency

Part of the UHF radio spectrum ranging eight MHz.


Multiplexing

The method that allows digital data from multiple sources to be transmitted through the same communication channel [such as an optical fiber or a UHF channel], thus allowing for better utilization of the high capacity telecommunication channels. To put it simply, for digital television multiplexing is the method that makes it possible for more than one channels to be broadcasted on each frequency along with supplementary services such as the electronic program guide [EPG].


MPEG-4

Technology for encoding and compressing audiovisual digital data. It is the most widespread method of saving and playing media and is the basis for the development of digital television.


Standard Definition [SD]

A television format that provides picture quality of normal resolution [576 lines].


High Definition [HD]

A television format that provides picture quality of high resolution [720 or 1080 lines].


 


Electronic program guide [ΕPG]

A service that provides information [projection times, duration, short description] regarding the channel’s program. Through our company, the EPG offers information for the weekly program of the nationwide privately-owned television stations, while at the same time, it is activated by more and more regional TV stations. The service supports Greek and English [so long they are provided by the channels] and is accessible via the remote of the TV set or the external decoder. Furthermore, the EPG allows for scheduled channel recording, channel lock, program start reminder, etc. Each television station is responsible for its program, the information provided and any sudden changes.


Teletext

It is a data transmission technique via a TV station’s signal, which is encoded and projected on the TV screen, so long the TV set supports the technology.

It uses the American Standard Code for Information Interchange [ASCII] encoding method, which consists of 128 characters [letters, numbers, punctuation marks, etc.] that appear on 40 horizontal and 23 vertical lines.

Teletext consists of 800 pages that can include information such as the news, weather forecasts, useful phone numbers, announcements, the channel’s program, lucky game results, etc.


 


Hellenic Telecommunication and Post Commission [Ε.Ε.Τ.Τ. in Greek]

H.T.P.C. is an independent body that regulates and supervises the electronic communication market within which mobile and landline telephony, wireless communication and internet companies operate. Regarding the digital switchover, H.T.P.C. is responsible for the granting of digital terrestrial broadcasting spectrum usage rights as well as the supervision of the spectrum use.


National Broadcasting Council [E.S.R. in Greek]

The N.B.C. is the independent body that controls the content of television and radio broadcasts.


International Telecommunication Union [I.T.U.]

The International Telecommunication Union is United Nation’s specialized organization within which governments and the private sector coordinate the establishment and operation of networks and telecommunication services. The I.T.U. is responsible for the regulation, standardization, coordination and development of international telecommunications, as well as the harmonization of national policies.