Digital television
As digital television is referred to the broadcasting of television programs in digital form. For this, the conventional (analog ) video and audio signals by means of so-called A / D converter into digital data streams ( binary code ) to be transformed.
The production and processing of video and audio signals has been happening for years ( from April 2006) in digital form. The distribution of sound and image data is done today ( 05/ 06) usually in digital form ( DVB- T, DVB- C, DVB- IPI, DVB- S, DVB -H, DMB, IPTV ). New TVs can display the digital signals (DVB) process directly (see IDTV ). For old analog TVs, the digital data stream with appropriate equipment ( digital receiver, set- top boxes ) must be converted back into analog signals ( see also digital -to-analog converter ). Partially done the dissemination of video and audio signals are still in an analogous manner (2005 /06). However, the old analog TV is coming to an end (see analogue switch-off ).
- Analog technology is the direct transfer of information through signal level change ( or variance ) ( more / less)
- Digital technology is the indirect transmission of information by interpretation of signal level changes ( off / on)
- 5.1 Comparison Chart
- 6.1 Market share of digital use
- 6.2 Distribution of the transmission paths in Germany
- 6.3 degree of digitization in the television reception paths in Germany
Standards and distribution methods
Most digital transmission standards work with data reduction, that is, that the amount of data of the digital source signals must be reduced at a loss in image quality against the spread in order to save data rate ( by reducing the bit rate). The data reduction system commonly used today is called MPEG and exists for both audio and video signals. The various MPEG-based codes can be used for data storage as well as for data transmission. In the development of the reduction process of the receipt of the maximum image quality at given bit rate is in the foreground. Even the popular MP3 format, or the current DVD standards based on MPEG. Depending on the broadcast platform, a distinction in digital television (DVB ), the following technical options: DVB -S ( satellite), DVB -T ( terrestrial antenna reception ), DVB -C ( cable), DVB -H ( mobile TV), DVB- IPTV (IPTV ); all based (currently ) on the MPEG- 2 standard.
Due to the digital broadcasting technology, numerous additional services with existing television programs can be combined: for example, data services with additional information and illustrations in the design of web pages; Advanced Teletext offers; Transmitter identifiers that enable fast location eg in automatic search and digital receiver; and last but not least digital program guides and information about the program ( EPG). By setting up a feedback channel ( on cable or via satellite), these services can be made interactive - that is, you can be registered as a user contact the advertiser, send e -mails or. As Triple Play is called the parallel distribution of radio, telephone and internet on the same transmission path ( eg cable ).
Digital transmission methods because of its high compatibility with computer systems (receiving, storing, editing, conversion or distribution ) are advantageous and timely; by the low distribution costs via satellite or cable (a digital television requires only one-tenth to one-fifth of the data rate of an analog channel ) may smaller providers distribute their services nationwide. In addition, to expand their existing offering inexpensive to numerous additional channels large television groups. A big advantage is also in the compatibility of radio and television standards DVB -T, so that in the data stream of HD bouquets a TV station can be exchanged for an equivalent number of radio stations, or vice versa, and the operators of the stations can better respond to the needs of program providers.
In Berlin since 2003 digital terrestrial television (DVB -T) mandatory. A hard switch ( analogue switch-off when posted on the digital signals ) is almost exclusively carried out for reasons of channel scarcity. Here are some DVB-T conversion scenarios for East Westphalia, Bavaria, Baden -Württemberg and Rhineland -Palatinate and Hesse. Nationwide, the transition was completed in late 2008 ..
Digital data streams can be displayed on the screen or recorded to disc (eg IPTV) in computer- based networks such as the Internet and spread with the appropriate software. Digital signals (English streams) can be transmitted in different standards, which are indeed related to each other but only limited compatible. Most receivers, however, can be updated via an update function via satellite, internet or cable or expand other transmission codes. Since nowadays many programs send encrypted, you need to receive the offer called the reception module, usually in the form of a plug-in card, which is inserted into the receiver. Because of the large variety of encryption systems, many modern devices have multiple card slots (slots ) in order to receive the services from different vendors can.
We call this cross-platform devices CICAM receiver = Common Interface Conditional Access Module. In contrast to the late 1990s by the Kirch Group for which at that time the pay- TV service Premiere were promoting d-box, which was suitable only for decryption of Premiere and other pay - TV providers discriminated containing CICAM receiver interfaces for all standard encryption technologies ( Betacrypt, Nagravision, Videoguard, Viaccess, Cryptoworks etc.).
Registration, maintenance and customer management is then usually online ( or via satellite). Thus, for the example of hackers cracked encryption codes replace them with others or exclude defaulting customers from reception. The devices have offered depending on the platform of different technologies, why can not be use for digital cable digital receiver for satellite reception, or vice versa.
History and current development
Development towards digital television
Digital TV was first offered commercially in the spring of 1994 by satellite under the brand name DirecTV in the United States.
End of 1993, twelve European countries agreed to as quickly as possible to create a specification for the transmission of digital television signals via satellite and cable; the launch was scheduled for 1995. The resulting adult DVB was first aired in Germany on 28 July 1996 by this newly created pay- TV operators DF1 ( Digital Television 1). Because of lack of success, despite large-scale advertising campaign and popular sporting events it was later with the pay TV channel Premiere from the same house, the Kirch Group, merged. The now listed station was able to expand its capacity thanks to the digital broadcasting technology strong and take lots of additional programs or thematic channels (including third party ) in his offer.
Meanwhile, began almost all national German television primarily via the Astra satellite operator SES parallel to the analog with the digital broadcast their programs. Besides additional accessible only for digital channels users especially many new thematic channels and some local stations use the inexpensive digital technology. Send Some minor television providers, the television signal via DSL or fiber-optic network through the Internet, where it is taken by the operators of an uplink station ( usually a larger television station) and transferred to the satellite. Thus, high transmission costs, as they would be incurred for the expensive radio technology, for example, is avoided. In this way, the spatial distance between the program supplier and transmitter is easily overcome.
Due to the nationwide expansion of the Internet and the introduction of ADSL2 as the new transmission standard digital TV can be received directly from the Internet in the future. Due to the high download rates with ADSL2 or light guides, the reception quality and interference resistance of the programs is as high as, for example, through traditional cable or via satellite. Gradually, the vision of a " global television" over, first along broadband data networks, reality would.
In early 2003 began a little later than in comparable countries ( eg Great Britain, 1996), the introduction of DVB -T, the terrestrial DVB- variant. In August of the same year, Germany took to the complete shutdown of analogue terrestrial television in the Greater Berlin Worldwide playing a pioneering role. After Berlin was followed by other metropolitan areas, with the switchover to DVB -T. Since 2004, individual programs or experimental channels were broadcast in HDTV standard in Europe. End of April 2012, the analogue satellite television was turned off.
Meanwhile, considerable debate about the admissibility of a toll- occupied basic digital encryption for commercial television programs such as RTL or SAT1, the medium term plan to introduce both via cable and satellite television operators. Regarding the current consolidation trends in digital television, see also project Entavio.
Great Britain
An opposite trend suggests itself in other countries: To share in the UK more and more programs on their encryption. Most British television programs are submitted on the platform of British Sky Broadcasting ( BSkyB), in addition to its own programs also marketed third-party offers and provided with a basic encryption during the 1990s. Many of these providers, including BBC and ITV, broke away from Sky and send now uncoded.
Currently, more than 120 intended for the UK market television channels are available unencrypted over satellite, including many full commercial and special interest programs. They are marketed under the labels of free-to -air (FTA, name for any unencrypted offers), Freesat ( brand name protected for application packages from BBC and ITV ) and Freeview ( terrestrial DVB -T reception with about 30 programs). To meet the competition, even the pay- TV group BSkyB took a private unencrypted ad-supported program in operation.
The encrypted offer BSkyB (Sky Digital) is the most extensive in Europe and offers a variety of movie, sports and entertainment channels as well as numerous thematic channels and third-party such as Disney, Discovery, NBC Universal or Viacom. BSkyB is part of the empire of media tycoon Rupert Murdoch (News Corporation).
Situation in other countries
In many European countries, encrypted cable bouquets have been established, which are mostly fed completely into the cable. Many stations encrypt licensing reasons, because they have only acquired broadcast rights for a limited coverage area. However, the reception of these programs is free, decryption cards (smart cards ) are usually shipped free of charge to viewers.
In the Netherlands, all full programs encrypt their signal via satellite, because all international productions, with the exception of some children's programs are broadcast in their original language ( with subtitles). Movie and sports offers are marketed in Canal Digitaal bouquet ( cable, satellite). The big cable companies offer digital packages that include not only Canal Digitaal the international TV brands such as Discovery and MTV. They are also provided with Dutch subtitles.
The situation is similar in Scandinavia and most Eastern European countries, where the expense resulting from the synchronization would be economically unviable (except Russia, partly Poland). To go to licensing problems out of the way, most all programs are coded. The strong position of subscription television in these countries is also explained by the small advertising market.
In Belgium, especially in Flanders, the digital program offer focused almost entirely on cable or ADSL. There is little direct satellite reception. Also in Switzerland are paid digital packages (especially Tele Club ) offered in the cable.
In Austria, the satellite has a strong position; the subscription area similar to Germany is almost exclusively Sky, which also applies to the cable reception.
In France, three major pay-TV networks, Canal Satellite numerique dominate (better known as Canal ), AB Sat and TPS ( Télévision par satellite). TPS and Canal have recently merged and will soon combine their offers. All three turn cooperate with numerous third-party, including the major national television channels. In France, very few programs are freely receivable.
About Eutelsat transmits Sky Italia, the dominant digital television provider in Italy. As he BSkyB is controlled by Rupert Murdoch. Sky Italia was formed from the merger of the two erstwhile competitors STREAM and TELE .
In Spain, the two digital platforms Vía Digital Telefónica and Canal Satellite Digital Sogecable merged to become monopolists Digital . The merger was due to a single program and structural policies and better earning potential. In the cable market leader AUNA and ONO dominate. Although in Spain nearly all international productions are broadcast with Spanish dubbing, encrypt most of the national TV channels you program via satellite. Lately, however, is an increasing trend to the unencrypted broadcast recorded; especially regional networks and many specialty stations go this route. Former pay-TV channels are increasingly to advertising-funded broadcasting.
A basic fee for commercial television offers are usually only in the cable. Some smaller broadcasters prefer, however, still a mixed financing, based on advertising and a low subscription fee. This basic subscription but is divided into a large number of special-interest channels, which are sold together in so-called base packages. This mixed financing is common when a program through advertising revenue alone can not be operated economically, such as the transmission area or the target group are too small.
GB20600 - 2006 is the name of the default system of the Chinese digital television.
Television on the Internet
With the IPTV methods ( Internet Protocol TV) numerous television programs using the Internet Protocol will be spread throughout the world today. Currently more than 200 thematic channels are available in German language, which can be received via any web-enabled device with sufficient computing power. These include, among other information channels of larger companies such as branding or travel agents; now, however, many high-quality journalism specialized channels are also already available to a wide variety of topics.
Still, the programs are designed exclusively for Internet channels, but they can be integrated in the near future problems in cable bouquets or distributed in any other way. So the internet can in future be used as a pure transmission, processing and receipt of services would then be at the cable companies. IPTV is not designed for mass reception, but it can be made suitable for mass production in a few years by upgrading with multicast-enabled servers. Recently, a quasi- monopoly around the Munich-based media entrepreneur Ingo Wolf has established that, based on the IPTV technology usually offers or redistributed numerous specialized programs unencrypted.
In the future, should the Internet for all television providers to the highly competitive terrain, RTL and SAT1/Pro7 will distribute their already shortly on the Internet (see also IPTV). Some operators, such as the cable provider HanseNet with its TV bouquet Alice or the German Telekom with its broadband transmission standard VDSL already offer IPTV television (including the high-resolution HDTV) based on IP Multicast, because of the still insufficient Internet capacity, but only within their own networks.
Transition from analog television to DVB-T
DVB- T is an abbreviation for the English term Digital Video Broadcasting Terrestrial ( to German as: Digital earthbound television) and refers to the terrestrial ( ground-based ) distribution of digital radio, television and data signals in the Earth's atmosphere. DVB -T is a variant of the Digital Video Broadcasting (DVB ), which is mainly used in various European, Asian and African countries as well as Australia as a standard for the transmission of digital television and radio via antenna.
In the Swiss Engadin, the intrusion of digital terrestrial television signal in German-speaking Europe was held for the first time on February 1 2003. Berlin followed on 4 August 2003, Austria nationwide uniform (multiplex A) until 26 October 2006. During the analogue switch-off has now been completed in all three countries, the regional multiplexes ( Mux C) in Austria are still built. Private programs are there in Germany mainly in the urban areas of the so-called " Home Islands " ( ie the place where it was started with the DVB-T transition ), in Austria 's private national television is widespread. In Switzerland there is because of the high rate cabling currently no need for private programs, which is why a multiplex with four to five public service programs is there only be received. In South Tyrol there is an abundant supply Italian and German language programs in all four countries, which are spread by the radio - Anstalt Südtirol, including, as in all of Italy, some programs in high-definition quality.
In Germany most four TV programs per multiplex be disseminated in other countries more ( in German-speaking Switzerland five programs ), or less, in addition radio programs ( in Austria and partly in Germany ) or HDTV content (eg in Italy). Moreover, it is in Germany from the beginning area, on the construction of single-frequency networks ( SFN ), and both UHF and VHF, while some other countries use at least initially multi-frequency networks ( mFNs ) or be limited to UHF.
The full transition to DVB -T, ie the abolition of analog television broadcasting was provided in Germany according to the resolution of the federal government no later than the year 2010. General to the broadcasting of analogue broadcasting (television and radio ) in the EU in April 2012 border (see analogue switch-off ).
Technology
The transfer takes place in Europe, as in most countries of the world in the DVB standard, in addition to television and radio programs, additional information (eg subtitles, EPG ) and new data services (such as texts, PC data, MHP) offers. There are various possibilities for DVB transmission:
- DVB -T ( terrestrial)
- DVB -C (cable)
- DVB- IPI (Internet)
- DVB -S ( satellite)
- DVB -H (terrestrial for mobile devices).
Japan uses a related method ( ISDB ), while the U.S. propagate their ATSC format at least for the antenna reception.
The bandwidth of a typical transponder ( satellite channel ) to the well-known broadcast satellite Astra is usually 33 MHz, corresponding to a net data rate of 36 Mbit / sec and a symbol rate of 26 Msymb / s A TV channel typically takes 3-4 Mbit / sec, depending on its symbol rate ( 2 bits for encoding a symbol). She moves from 2.2 to 2.75 Msymb / s Together with the error correction (usually 3/4 signal-to- data correction ) gives the required data rate. The faster the picture changes ( changes in the image structure ), the higher is the required data rate. So sports and action scenes require more bandwidth than low-motion sequences ( talk shows, etc.). If the range is calculated to be narrow, it comes with quick change of scene at higher resolution for artifacts ( building blocks - effects).
Usually via a transponder even radio programs with a data rate 64-320 kbit / sec in MPEG1 -L2- standard as well as various data services transmitted. About a pure television transponder can be conveniently eight television programs transmitted in good quality, but only an analog. The introduction of the more efficient MPEG -4 codecs can compress even more effective in the future, while maintaining the same picture and sound quality can be in the future more than 10 channels per transponder transmitted. By the time consuming encoding and decoding of the television signal, it is compared to the analog broadcasting to more seconds of delay. Is compressed more efficiently, the more complicated is the encoding algorithm.
For DVB TV-in MPEG -2 is first encoded, then the program is interleaved with any additional services in the multiplexer. Several programs (television, radio, etc.) within a packet can thus be combined into one data stream, which is also called transport stream. Subsequently, the data stream is modulated with the carrier signal, amplified and directed to the channel or satellite or cable headend.
Comparison Chart
The following table explains the differences between analog and digital television based on individual aspects.
Statistical data
Market share of the digital use
The market share for digital television in Germany on the 1st of January of each year based on the data of the Television Research ( AGF), TV Scope, Basis TV panel D EU: