Teletext

Under Teletext ( in Germany: Teletext ) is understood as a form of communication for disseminating news, lyrics and pictorial representations, which are broadcast in the blanking interval of the television signal of a television station, and from which the user can select the desired information for display on the screen of a television.

• 6.1 Germany
• 6.2 France
• 6.3 United Kingdom
• 6.4 Sweden
• 6.5 Austria 6.5.1 Outline of the ORF Teletext

Transmission and practice

An analog television picture central European television standard has 625 scan lines. Of only 576 lines for the transmission of an image contents are used, the remainder is the blanking interval, during which the TV prepares for receiving the next image. So in the early 1970s British television technician for the BBC came up with the idea of ​​transferring sensitive information in this unused area. It was issued in 1974 the first specification of the U. K. teletext standard. Meanwhile, text data are organized by page and can accommodate 25 lines of 40 characters of text ( 23 lines can be freely edited, the other for headers and footers reserved). The pages can be designed with 96 different letters, numbers and special characters as well as 128 graphic characters. This corresponds to the state of the art at the time of introduction of Teletext. The background can usually be between opaque ( for readability ) and transparent switching ( to track the program). Each panel is associated with a language that is encoded in 3 bits and basically covers all Western European languages ​​by character substitution in accordance with ISO 646. In addition, there were in the Soviet Union teletext with Cyrillic and the Middle East with Arabic script.

Older TV build each page separately from the data stream on, which can lead to long waiting times. Since not all pages are simultaneously encoded in the blanking interval, these devices will have to wait until the requested page is broadcast. Today's standard page memory in television sets were too expensive despite the low volume of data in the early days of the teletext system manufacturers view. In older devices, individual pages could be determined, which should end up in the memory and thus were more readily available. However, since nowadays the prices of memory chips have fallen sharply, current devices usually have a memory with a circumference of ten to more than 2000 pages ( marketed under terms such as Mega text or TOP text ) from which the page can be retrieved. Although teletext page numbers only from 100-899 (coding see below) can have a memory of more than 800 pages is useful: this memory can store even the undersides of individual panels.

Although the teletext service is always transferred with the current TV picture, a recording of the text with the program with standard analog video tape recorders ( VCR ) is usually due to the low bandwidth hardly possible to have S -VHS or better professional systems (eg Betacam SP ) is required. For transmission, the lines 7-15, 20-21 in the first field and 320-328, 333-334 used in the second Halbild.

Data rate

A European PAL TV image allows the vertical blanking interval of a data transmission of up to 128 kbit / s Teletext required, depending on text level only 15 kbit / s to 47.5 kbit / s

Addressing

The individual pages or sheets are selected by a three-digit code. The first digit of the page number, the so-called magazine is encoded with 3 bits and can only take the values ​​1-8 (0 is interpreted as 8 ), the second and third digits are 4-bit encoding, which also hexadecimal numbers are possible, however, the one with the normal televisions can not call. Addresses like 1F6 or 8AA, however partially used for test pages, control pages for the TOP text or toll Teletext offers.

The pages are transmitted sequentially in a loop; since in each blanking interval adapt only a few data, it therefore takes a long time after the election one side until it is sent back. The result is stored in the receiver, so that it can be considered alone. Better televisions have now often stores where many ( typically 10 to 2000), or all pages, sometimes even sub-pages can be stored simultaneously. Thus, these are then immediately upon selection available. Only after a channel change, it still takes some time ( one to two minutes ) until the sides of the new station is stored. To avoid the waiting periods, which occur particularly often in the transferred or non-existent pages, many teletext services can also be accessed via the Internet. Here, the references are ( sometimes simply all combinations of three digits ) converted to other pages into hyperlinks to the corresponding page.

Page occupancy

Content of the message text are mostly program-related Additional information, the television or news. Many private channels also send advertising, primarily for pay telephone hotlines, sweepstakes or adult offers. Chance has also experimented with interactive teletext pages in which a caller was able to quit for example classifieds via a touch-tone phone, the significance of these services has declined over the Internet. In contrast, SMS-based interactive services (SMS chat, even classified ads ) are quite common among German private broadcasters now.

In the German, Austrian and Swiss full programs ( The first, ZDF, RTL, Sat.1, ProSieben, VOX, Kabel eins, RTL 2, one ORF, ORF 2, ORF III ORF SPORT , 1 SRF, SRF two, SRF info and 3 ), the following breakdown of the contents:

• Page 100 is the home page
• Page 101 et seq News ( Swiss TV: page 110 ff )
• Page 200 ff Sports ( Swiss Television SRF: page 180 ff )
• Page 300 et seq TV program
• Page 333 name of the program currently being broadcast (transparent)

In addition, additional messages available (especially in public ) on specific topics on other sites (eg, science, health, nature, economy, stock quotes and celebrity news) for the nightly news is not a time depending on the broadcasters. In addition, program-related information for future reference, tips, arrival and departure times at airports, congestion forecasts, world time, in the third programs also traffic news etc.

Pages may be composed of several sub-pages which are successively transmitted and displayed. Such sites can be identified by markings, such as 1/2 ( first of two bases ).

Almost everyone teletext service sends on one side, a test image, with the available character set and representation of letters in double height, blinking text and hidden information ( puzzle ) key and another side, the clock cracker test page that is displayed correctly if the clock frequency is the decoder to a TV picture in sync. When the Clock crackers will not show up correctly, the decoder is running too fast or too slow and needs to be readjusted.

Send Some stations at certain shipments, including subtitles for the hearing impaired via teletext. This will include the dialogues of the people and describe important sounds. The subtitle is usually located on pages 777 (ZDF, ORF, Switzerland ), 149 ( private broadcasters) or 150 (ARD and third parties).

Most teletext services provide a preview for the next few days, some even for multiple transmitters. Many stations offer a tablet on which is to see what is sent and just next. It is a small text box appears in the picture, so you can continue to follow the current TV program. In German channels usually panel 333 is used for this. Because teletext is constantly updated by an editorial, program changes appear there usually immediately.

Even at sporting events such as Football matches are displayed in a corner of the screen without the rest of the image to cover the current results.

Improvements for the Ease of Access

TOP ( Table Of Pages)

To facilitate the operation, was introduced in Germany the TOP text system ( Table of Pages ). About data on specific control sites, the individual panels are divided into categories, so-called blocks for a higher hierarchy level (eg news, sports, program) and groups below (eg Home / Abroad, football / tennis). The pages Abbreviations can be assigned, which can be displayed as a colored line 25 and selected with four colored buttons on the remote control. Information is also transmitted which pages exist and which have sub-pages that help the decoder line 25 generates or eg also may indicate that a selected page does not exist.

FLOF (Full Level One Facilities)

FLOF system (Full Level One Facilities), also called FasText, with each side can be transmitted separately, the 25th row with names, numbers and representation of the jump destinations. The editorial, has the opportunity to make these references to up to four pages themselves and the reader to eg related topics for (or advertising pages, etc. ) to direct. An information which pages exist or have sub-pages is not available in FLOF. Also, unlike TOP, only displayed for each page associated information in the 25th line in locating the selected page, and not already when entering the page number as in TOP.

By now, most decoders support both and use almost all of teletext services one of the systems - in Germany the most TOP, in other countries often FLOF.

HiText

Another backward-compatible extension of the teletext standard and is called Level 2.5 or HiText allows among others to the free definition of 16 colors, enhanced special characters and the free definition have their own character, so higher resolution graphics are possible. This is not so far been supported by relatively few decoders and therefore only offered a few teletext services. Most HiText is used only for the own station logo.

Provider

Currently available in the German language area

• ZDF Text
• BR -alpha
• Bayerisches Fernsehen
• SWR Fernsehen
• 3sat
• Phoenix

The HiText.

The ARD, NDR, ProSieben and arte only have tests carried out or if the time was limited. The Bavarian television had introduced it in 1999 as the first institution within the ARD, by its own account but stopped in 2005 and finally adopted it 2011.

Outside the German-speaking 2.5 Level 3 ( station logo, background color ) and NOS - text in the Netherlands (background, as well as test page 389 ) as applied to France.

Level 3.5

The teletext standard ETSI EN 300 706 yet defined any exceeding Level 3.5 ( colored with high-resolution graphics, proportional font, etc.), which is hardly supported by decoders or services.

Other operating facilities

At the level decoder / TV / remote control, there are a variety of functions that facilitate the operation:

• Change in the presentation of the color and font size
• Selective dialing of a bottom
• The so-called Page Catching allows it to follow the page numbers shown as a link in the text: The system recognizes these successive three digits; with the remote control buttons, this can be selected, and press the OK button selects the decoder this page number.

Individual countries

Germany

The common teletext ARD and ZDF, whose ten -year test phase began on 1 June 1980 was named Teletext, to avoid confusion with the then teletex service. Therefore, in Germany Teletext offers are often referred to as teletext.

The regular operation started in 1990. The editorial work in the video text of ARD and ZDF was in charge cared for by the Sender Freies Berlin ( SFB). As of December 1999, separated the partner ARD and ZDF to launch two independent offers. Since then, the CRC was responsible for the ARD text. After the merger, the transmitter SFB and East German Rundfunk Brandenburg (ORB) most of the content from the Rundfunk Berlin -Brandenburg ( RBB) from Potsdam to edit. The current political content of ARD text are processed by the editors Tagesschau.de the Norddeutscher Rundfunk ( NDR) in Hamburg.

Meanwhile feature almost all regional and national programs have their own teletext services, for example the NDR television since 30 September 1988.

In 2010, Germany had in the teletext ARD with 18,6 % the largest market share, ahead of ZDF and RTL 14.8% with 13.4 % market share.

As of August 16, 2012 festival was held a month-long International Teletext Art in teletext ARD.

France

In France they had developed a graphically elaborate standard called Antiope, but which was never widely distributed and was later replaced by teletext.

United Kingdom

In the UK the first Ceefax test broadcasts were still in black and white before also allowed different font colors in UK teletext standard. Ceefax was shut down in stages as part of the switch to digital transmission technology in 2012. Unlike in Germany, not a classic teletext is transmitted via digital channels only. There, BBC Red Button is offered instead, which is more similar to an interactive, multimedia program guide.

Sweden

As the first station outside of the United Kingdom began SVT in Sweden on March 12, 1979 teletext test transmissions.

Austria

The third broadcaster in Europe with teletext ORF followed in Austria on 21 January 1980. Teletext various private broadcasters in Austria often had to suspend criticism, since it was not designed youth fit, the information of advertisement is displaced and " only provides a platform for advertisements and signs representing ".

Outline of the ORF Teletext

Since 16 March 2009, the ORF Teletext has a new design. It can be accessed now the regional news of the regional studios. The teletext ORF is divided into various categories, these include " sports ", " politics", " Chronicle " and "TV program information " and " Culture and Show," " Multimedia ," health ", " travel ", " Fun and star "and" Help ". As an additional focus of the ORF Teletext service information also offered are considered that are provided by cooperation partners for several years. Services range of weather information and continually updated stock exchanges and market data on departures and arrivals at airports as well as arrivals and departure of the train stations. It also lists traffic information or emergency phone numbers. The teletext of the ORF can be queried via the Internet.

Switzerland

The teletext of SRF (then DRS and SF1, SF2 ) was first aired in 1984. The broadcast in French-speaking Switzerland in 1985, in the Italian 1986. Since 1994 interactive services were offered in teletext. Next View offers on the Swiss Teletext 1997. 2001 from an average daily attendance of 1.17 million in 2004 from 1.3 million viewers has been reached. Although new media emerged as the Internet was the use of record during the Olympic Games in Turin in 2006.

The teletext on Swiss television ( since 2011 Swiss radio and television) can be queried via the Internet. Especially because in comparison to other Internet teletext services, is that also a mobile version was launched.

USA

In the United States was already experimenting from the late 1970s on several occasions with teletext. But in 1990 a special subtitle decoder for the hearing impaired in every new TV is required by law, the manufacturer can choose not to install an additional general teletext decoder. Therefore, no teletext is there today practically broadcast.

Related Services

In the blanking interval, various other data may be transmitted, such as VPS signal, data (such as channel Videodat ), music or videos.

Digital television graphics and content more sophisticated content than in technologically obsolete teletext are especially made ​​possible by the DVB- MHP standard possible. Currently, however, most of the channels to take on even the contents of the teletext for their digital programs to relieve the editors. The program information is available on digital TV via the electronic program guide ( EPG).

Sometimes the teletext service is confused because of the name with the screen text ( BTX ), which also helped that BTX in Switzerland Videotex was called (without t end ). Teletex other hand, is an advanced form of the telex.