Datacasting
Encyclopedia
Datacasting is the broadcasting
of data
over a wide area via radio wave
s. It most often refers to supplemental information
sent by television station
s along with digital television
, but may also be applied to digital
signals on analog TV or radio
. It generally does not apply to data which is inherent to the medium, such as PSIP data which defines virtual channel
s for DTV or direct broadcast satellite
systems; or to things like cable modem
or satellite modem
, which use a completely separate channel for data.
, weather
, traffic
, stock market
, and other information
which may or may not relate to the program[s] it is carried with. It may also be interactive, such as gaming, shopping
, or education
. An electronic program guide
is usually included, although this stretches the definition somewhat, as this is often considered inherent to the digital broadcast standard.
The ATSC, DVB and ISDB
standards allow for broadband
datacasting via DTV, though they do not necessarily define how. The overscan
and VBI are used for analog TV, for moderate and low bandwidths (including closed captioning
in the VBI) respectively. DirectBand
and RDS
/RBDS are medium and narrow subcarrier
s used for analog FM radio. The EUREKA 147 and HD Radio
standards both allow for datacasting on digital radio
, defining a few basics but also allowing for later expansion.
The term IP Datacasting (IPDC) is used in DVB-H
for the technical elements required to send IP
packets over DVB-H broadband downstream channel combined with a return channel over a mobile communications network such as GPRS
or UMTS
. The set of specifications for IP Datacast (phase1) was approved by the DVB project in October 2005.
presently hosted by U.S.A. Mobility, a U.S. paging service and focuses on information of interest to the local (or larger) area, such as weather and stock indices, and with a paid subscription Ambient will provide a particular device with more personalized information.
, RBDS is carried on a 57kHz subcarrier
on FM
radio station
s. While originally intended for program-associated data
, it can also be used for datacasting purposes including paging
and dGPS.
, owned by Microsoft
, uses the 67.65 kHz subcarrier leased from FM radio stations. This subcarrier delivers about 12 kbit/s (net after error correction) of data per station, for over 100 MB per day per city. Data includes traffic
, sports, weather, stocks, news, movie times, calendar appointments, and local time.
service used dNTSC technology by Dotcast to transmit 720p
HDTV movies in the lower vestigial sideband of NTSC
analog TV. The set-top box
stored the movies to be viewed on demand
for a fee
. This was distributed through PBS's National Datacast
.
-supported datacast sent by one local station in each media market
. It supplements or replaces the limited electronic program guide
sent by each TV station, which is already mandated by the U.S. Federal Communications Commission
(FCC).
is yet another mobile TV
standard, although it is transmitted and controlled by the broadcasters instead of a third party, and is therefore mostly free to air (although it can also be subscription-based). From a technical standpoint, it is an IP-encapsulate
d datacast of MPEG-4
streaming video, alongside the ATSC
MPEG transport stream used for over-the-air
HDTV/SDTV broadcasting. Heavy error correction, separate from that native to ATSC, compensates for ATSC's poor mobile (and often fixed) reception.
s to update
their firmware
via over-the-air programming
. This is also transmitted on PBS stations via National Datacast.
system for use in Australia.
The trial consisted of a number of services on one standard 7MHz multiplex
, collectively known as Digital Forty Four
.
The collection included:
More recently a near-Australia wide broadcast of a datacasting channel called MyTalk
commenced on April 13, 2007. Broadcasting as part of the multiplex on Southern Cross
and Southern Cross Ten
stations, it provided news, weather and other information, available free to anyone able to tune in. The stream consisted of text applicable to the viewer's location and a 4:3 video window of broadcast TV from the relevant Southern Cross
/Southern Cross Ten
station.
On February 25, 2008, MyTalk ceased broadcasting. Digital Forty Four was shut down at exactly midnight on the night of April 30, 2010.
has developed an IP satellite datacast platform for the distribution of educational and health content to sites around South Africa and increasingly throughout the rest of Africa as well. The model is a forward and store model allowing users of the platform to view content in an on-demand fashion. Content distributed in this way includes video content, print-based content (in the form of PDF files), as well as interactive computer-based multimedia content.
Significantly, the model also includes access to a GPRS network that allows the receiving sites to communicate back to the Mindset central server. Communications include statistics about the physical health of the machine (e.g. power status, disk drive usage) as well as usage statistics indicating what content has been viewed.
The model also includes a distributed deployment of the Moodle
LMS, allowing users to take assessments and then have the results transmitted via GPRS to the Mindset server for accreditation.
is used extensively on analogue channels; a type of Datacasting using the Overscan
on analogue transmissions. Teletext Limited and Ceefax are the main providers. Within Digital television the Digital Teletext name is used extensively although the technology used to provide this service is unrelated and uses the MHEG-5
UK profile.
Broadcasting
Broadcasting is the distribution of audio and video content to a dispersed audience via any audio visual medium. Receiving parties may include the general public or a relatively large subset of thereof...
of data
Data
The term data refers to qualitative or quantitative attributes of a variable or set of variables. Data are typically the results of measurements and can be the basis of graphs, images, or observations of a set of variables. Data are often viewed as the lowest level of abstraction from which...
over a wide area via radio wave
Radio Wave
Radio Wave may refer to:*Radio frequency*Radio Wave 96.5, a radio station in Blackpool, UK...
s. It most often refers to supplemental information
Information
Information in its most restricted technical sense is a message or collection of messages that consists of an ordered sequence of symbols, or it is the meaning that can be interpreted from such a message or collection of messages. Information can be recorded or transmitted. It can be recorded as...
sent by television station
Television station
A television station is a business, organisation or other such as an amateur television operator that transmits content over terrestrial television. A television transmission can be by analog television signals or, more recently, by digital television. Broadcast television systems standards are...
s along with digital television
Digital television
Digital television is the transmission of audio and video by digital signals, in contrast to the analog signals used by analog TV...
, but may also be applied to digital
Digital
A digital system is a data technology that uses discrete values. By contrast, non-digital systems use a continuous range of values to represent information...
signals on analog TV or radio
Radio
Radio is the transmission of signals through free space by modulation of electromagnetic waves with frequencies below those of visible light. Electromagnetic radiation travels by means of oscillating electromagnetic fields that pass through the air and the vacuum of space...
. It generally does not apply to data which is inherent to the medium, such as PSIP data which defines virtual channel
Virtual channel
In telecommunications, a logical channel number , also known as virtual channel, is a channel designation which differs from that of the actual radio channel on which the signal travels....
s for DTV or direct broadcast satellite
Direct broadcast satellite
Direct broadcast satellite is a term used to refer to satellite television broadcasts intended for home reception.A designation broader than DBS would be direct-to-home signals, or DTH. This has initially distinguished the transmissions directly intended for home viewers from cable television...
systems; or to things like cable modem
Cable modem
A cable modem is a type of network bridge and modem that provides bi-directional data communication via radio frequency channels on a HFC and RFoG infrastructure. Cable modems are primarily used to deliver broadband Internet access in the form of cable Internet, taking advantage of the high...
or satellite modem
Satellite modem
A satellite modem or sat modem is a modem used to establish data transfers using a communications satellite as a relay.There is a wide range of satellite modems from cheap devices for home internet access to expensive multifunctional equipment for enterprise use.A "modem" stands for...
, which use a completely separate channel for data.
Overview
Datacasting often provides newsNews
News is the communication of selected information on current events which is presented by print, broadcast, Internet, or word of mouth to a third party or mass audience.- Etymology :...
, weather
Weather
Weather is the state of the atmosphere, to the degree that it is hot or cold, wet or dry, calm or stormy, clear or cloudy. Most weather phenomena occur in the troposphere, just below the stratosphere. Weather refers, generally, to day-to-day temperature and precipitation activity, whereas climate...
, traffic
Traffic
Traffic on roads may consist of pedestrians, ridden or herded animals, vehicles, streetcars and other conveyances, either singly or together, while using the public way for purposes of travel...
, stock market
Stock market
A stock market or equity market is a public entity for the trading of company stock and derivatives at an agreed price; these are securities listed on a stock exchange as well as those only traded privately.The size of the world stock market was estimated at about $36.6 trillion...
, and other information
Information
Information in its most restricted technical sense is a message or collection of messages that consists of an ordered sequence of symbols, or it is the meaning that can be interpreted from such a message or collection of messages. Information can be recorded or transmitted. It can be recorded as...
which may or may not relate to the program[s] it is carried with. It may also be interactive, such as gaming, shopping
Shopping
Shopping is the examining of goods or services from retailers with the intent to purchase at that time. Shopping is an activity of selection and/or purchase. In some contexts it is considered a leisure activity as well as an economic one....
, or education
Education
Education in its broadest, general sense is the means through which the aims and habits of a group of people lives on from one generation to the next. Generally, it occurs through any experience that has a formative effect on the way one thinks, feels, or acts...
. An electronic program guide
Electronic program guide
Electronic program guides and interactive program guides provide users of television, radio, and other media applications with continuously updated menus displaying broadcast programming or scheduling information for current and upcoming programming...
is usually included, although this stretches the definition somewhat, as this is often considered inherent to the digital broadcast standard.
The ATSC, DVB and ISDB
ISDB
Integrated Services Digital Broadcasting is a Japanese standard for digital television and digital radio used by the country's radio and television stations. ISDB replaced the previously used MUSE "Hi-vision" analogue HDTV system...
standards allow for broadband
Broadband
The term broadband refers to a telecommunications signal or device of greater bandwidth, in some sense, than another standard or usual signal or device . Different criteria for "broad" have been applied in different contexts and at different times...
datacasting via DTV, though they do not necessarily define how. The overscan
Overscan
Overscan is extra image area around the four edges of a video image that may not be seen reliably by the viewer. It exists because television sets in the 1930s through 1970s were highly variable in how the video image was framed within the cathode ray tube .-Origins of overscan:Early televisions...
and VBI are used for analog TV, for moderate and low bandwidths (including closed captioning
Closed captioning
Closed captioning is the process of displaying text on a television, video screen or other visual display to provide additional or interpretive information to individuals who wish to access it...
in the VBI) respectively. DirectBand
DirectBand
DirectBand is a North American wireless datacast network owned and operated by Microsoft. It uses FM radio broadcasts in over 100 cities to constantly transmit data to a variety of devices, including portable GPS devices, wristwatches and home weather stations....
and RDS
Radio Data System
Radio Data System, or RDS, is a communications protocol standard for embedding small amounts of digital information in conventional FM radio broadcasts. RDS standardises several types of information transmitted, including time, station identification and programme information.Radio Broadcast Data...
/RBDS are medium and narrow subcarrier
Subcarrier
A subcarrier is a separate analog or digital signal carried on a main radio transmission, which carries extra information such as voice or data. More technically, it is an already-modulated signal, which is then modulated into another signal of higher frequency and bandwidth...
s used for analog FM radio. The EUREKA 147 and HD Radio
HD Radio
HD Radio, which originally stood for "Hybrid Digital", is the trademark for iBiquity's in-band on-channel digital radio technology used by AM and FM radio stations to transmit audio and data via a digital signal in conjunction with their analog signals...
standards both allow for datacasting on digital radio
Digital radio
Digital radio has several meanings:1. Today the most common meaning is digital radio broadcasting technologies, such as the digital audio broadcasting system, also known as Eureka 147. In these systems, the analog audio signal is digitized into zeros and ones, compressed using formats such as...
, defining a few basics but also allowing for later expansion.
The term IP Datacasting (IPDC) is used in DVB-H
DVB-H
DVB-H is one of three prevalent mobile TV formats. It is a technical specification for bringing broadcast services to mobile handsets. DVB-H was formally adopted as ETSI standard EN 302 304 in November 2004. The DVB-H specification can be downloaded from the official DVB-H website...
for the technical elements required to send IP
Internet Protocol
The Internet Protocol is the principal communications protocol used for relaying datagrams across an internetwork using the Internet Protocol Suite...
packets over DVB-H broadband downstream channel combined with a return channel over a mobile communications network such as GPRS
General Packet Radio Service
General packet radio service is a packet oriented mobile data service on the 2G and 3G cellular communication system's global system for mobile communications . GPRS was originally standardized by European Telecommunications Standards Institute in response to the earlier CDPD and i-mode...
or UMTS
Universal Mobile Telecommunications System
Universal Mobile Telecommunications System is a third generation mobile cellular technology for networks based on the GSM standard. Developed by the 3GPP , UMTS is a component of the International Telecommunications Union IMT-2000 standard set and compares with the CDMA2000 standard set for...
. The set of specifications for IP Datacast (phase1) was approved by the DVB project in October 2005.
Ambient Information Network
Ambient Information Network, a datacasting network owned by Ambient DevicesAmbient Devices
Ambient Devices, Inc. is a privately held company based in Cambridge, Massachusetts, USA that designs and markets various ambient devices for display of information ranging from weather to traffic reports to stock quotes. The company was founded by David L. Rose, Ben Resner, and Pritesh Gandhi,...
presently hosted by U.S.A. Mobility, a U.S. paging service and focuses on information of interest to the local (or larger) area, such as weather and stock indices, and with a paid subscription Ambient will provide a particular device with more personalized information.
RBDS
A slight variation of the European Radio Data SystemRadio Data System
Radio Data System, or RDS, is a communications protocol standard for embedding small amounts of digital information in conventional FM radio broadcasts. RDS standardises several types of information transmitted, including time, station identification and programme information.Radio Broadcast Data...
, RBDS is carried on a 57kHz subcarrier
Subcarrier
A subcarrier is a separate analog or digital signal carried on a main radio transmission, which carries extra information such as voice or data. More technically, it is an already-modulated signal, which is then modulated into another signal of higher frequency and bandwidth...
on FM
FM broadcasting
FM broadcasting is a broadcasting technology pioneered by Edwin Howard Armstrong which uses frequency modulation to provide high-fidelity sound over broadcast radio. The term "FM band" describes the "frequency band in which FM is used for broadcasting"...
radio station
Radio station
Radio broadcasting is a one-way wireless transmission over radio waves intended to reach a wide audience. Stations can be linked in radio networks to broadcast a common radio format, either in broadcast syndication or simulcast or both...
s. While originally intended for program-associated data
Program-associated data
Program Associated Data or Program Service Data is a concept related to broadcasting which consists of a number of different fields or streams which are displayed on many HD Radio & satellite radio receivers in order to describe the program being transmitted, including different information such...
, it can also be used for datacasting purposes including paging
Paging
In computer operating systems, paging is one of the memory-management schemes by which a computer can store and retrieve data from secondary storage for use in main memory. In the paging memory-management scheme, the operating system retrieves data from secondary storage in same-size blocks called...
and dGPS.
DirectBand
DirectBandDirectBand
DirectBand is a North American wireless datacast network owned and operated by Microsoft. It uses FM radio broadcasts in over 100 cities to constantly transmit data to a variety of devices, including portable GPS devices, wristwatches and home weather stations....
, owned by Microsoft
Microsoft
Microsoft Corporation is an American public multinational corporation headquartered in Redmond, Washington, USA that develops, manufactures, licenses, and supports a wide range of products and services predominantly related to computing through its various product divisions...
, uses the 67.65 kHz subcarrier leased from FM radio stations. This subcarrier delivers about 12 kbit/s (net after error correction) of data per station, for over 100 MB per day per city. Data includes traffic
Traffic
Traffic on roads may consist of pedestrians, ridden or herded animals, vehicles, streetcars and other conveyances, either singly or together, while using the public way for purposes of travel...
, sports, weather, stocks, news, movie times, calendar appointments, and local time.
MovieBeam
The now-defunct MovieBeamMovieBeam
MovieBeam was a video-on-demand service started by Disney. Movies were sent wirelessly into the subscriber's home by embedding digital data within local Public Broadcasting Service stations' analog TV broadcast to deliver the movies to a set-top box...
service used dNTSC technology by Dotcast to transmit 720p
720p
720p is the shorthand name for 1280x720, a category of High-definition television video modes having a resolution of 1080 or 720p and a progressive scan...
HDTV movies in the lower vestigial sideband of NTSC
NTSC
NTSC, named for the National Television System Committee, is the analog television system that is used in most of North America, most of South America , Burma, South Korea, Taiwan, Japan, the Philippines, and some Pacific island nations and territories .Most countries using the NTSC standard, as...
analog TV. The set-top box
Set-top box
A set-top box or set-top unit is an information appliance device that generally contains a tuner and connects to a television set and an external source of signal, turning the signal into content which is then displayed on the television screen or other display device.-History:Before the...
stored the movies to be viewed on demand
Video on demand
Video on Demand or Audio and Video On Demand are systems which allow users to select and watch/listen to video or audio content on demand...
for a fee
Pay-per-view
Pay-per-view provides a service by which a television audience can purchase events to view via private telecast. The broadcaster shows the event at the same time to everyone ordering it...
. This was distributed through PBS's National Datacast
National Datacast
National Datacast Incorporated is a pioneer in data broadcasting.It is a for-profit subsidiary of the Public Broadcasting Service which handles datacasting on PBS TV stations throughout the United States...
.
TV Guide On Screen
TV Guide On Screen is an advertisingAdvertising
Advertising is a form of communication used to persuade an audience to take some action with respect to products, ideas, or services. Most commonly, the desired result is to drive consumer behavior with respect to a commercial offering, although political and ideological advertising is also common...
-supported datacast sent by one local station in each media market
Media market
A media market, broadcast market, media region, designated market area , Television Market Area , or simply market is a region where the population can receive the same television and radio station offerings, and may also include other types of media including newspapers and Internet content...
. It supplements or replaces the limited electronic program guide
Electronic program guide
Electronic program guides and interactive program guides provide users of television, radio, and other media applications with continuously updated menus displaying broadcast programming or scheduling information for current and upcoming programming...
sent by each TV station, which is already mandated by the U.S. Federal Communications Commission
Federal Communications Commission
The Federal Communications Commission is an independent agency of the United States government, created, Congressional statute , and with the majority of its commissioners appointed by the current President. The FCC works towards six goals in the areas of broadband, competition, the spectrum, the...
(FCC).
ATSC-M/H
ATSC-M/HATSC-M/H
ATSC-M/H is a standard in the USA for mobile digital TV, that allows TV broadcasts to be received by mobile devices.....
is yet another mobile TV
Mobile TV
Mobile television usually means television watched on a small handheld device. It may be a pay TV service broadcast on mobile phone networks or received free-to-air via terrestrial television stations from either regular broadcast or a special mobile TV transmission format...
standard, although it is transmitted and controlled by the broadcasters instead of a third party, and is therefore mostly free to air (although it can also be subscription-based). From a technical standpoint, it is an IP-encapsulate
Encapsulation (networking)
In computer networking, encapsulation is a method of designing modular communication protocols in which logically separate functions in the network are abstracted from their underlying structures by inclusion or information hiding within higher level objects....
d datacast of MPEG-4
MPEG-4
MPEG-4 is a method of defining compression of audio and visual digital data. It was introduced in late 1998 and designated a standard for a group of audio and video coding formats and related technology agreed upon by the ISO/IEC Moving Picture Experts Group under the formal standard ISO/IEC...
streaming video, alongside the ATSC
ATSC
ATSC standards are a set of standards developed by the Advanced Television Systems Committee for digital television transmission over terrestrial, cable, and satellite networks....
MPEG transport stream used for over-the-air
Over-the-air
Over-the-air has several meanings, depending on context. *Generally, over-the-air is synonymous for wireless.*Specifically, over-the-air can have the following meanings or is used in the following contexts:...
HDTV/SDTV broadcasting. Heavy error correction, separate from that native to ATSC, compensates for ATSC's poor mobile (and often fixed) reception.
UpdateTV
UpdateTV is a service used by some brands of TV sets and other ATSC tunerATSC tuner
An ATSC tuner, often called an ATSC receiver or HDTV tuner is a type of television tuner that allows reception of digital television television channels transmitted by television stations in North America, parts of Central America and South Korea that use ATSC standards...
s to update
Software Update
Software Update is a software tool by Apple Inc. that installs the latest version of Apple software on computers running Mac OS X. It was originally introduced to Mac users in Mac OS 9. A Windows version has been available since the introduction of iTunes 7, under the name Apple Software Update....
their firmware
Firmware
In electronic systems and computing, firmware is a term often used to denote the fixed, usually rather small, programs and/or data structures that internally control various electronic devices...
via over-the-air programming
Over-the-air programming
Over-the-air programming refers to various methods of distributing new software updates or configuration settings to devices like cellphones and set-top boxes...
. This is also transmitted on PBS stations via National Datacast.
Australia
Australian broadcast infrastructure company Broadcast Australia undertook a three year trial in Sydney of a datacasting service using the DVB-TDVB-T
DVB-T is an abbreviation for Digital Video Broadcasting — Terrestrial; it is the DVB European-based consortium standard for the broadcast transmission of digital terrestrial television that was first published in 1997 and first broadcast in the UK in 1998...
system for use in Australia.
The trial consisted of a number of services on one standard 7MHz multiplex
Multiplex (TV)
A multiplex or mux is a group of TV channels that are mixed together for broadcast over a digital TV channel and separated out again by the receiver...
, collectively known as Digital Forty Four
Digital Forty Four
Digital Forty Four was a Sydney-only trial datacasting service which was licensed by the Australian Broadcasting Authority in March 2004 for an initial three year run until late 2007...
.
The collection included:
- A combined program guide for the free-to-air broadcasters (Channel 4)
- ABC news, sport, and weather items (Channel 41)
- Channel NSWChannel NSWChannel NSW was a community information digital television channel that was currently running under trial in the Sydney area. The service was provided and operated by the Government of New South Wales...
(link) Government and Public Information, including real time traffic information and life surf webcam images (Channel 45) - Australian Christian ChannelAustralian Christian ChannelThe Australian Christian Channel is a Christian channel featured on subscription-based television in Australia. The Australian Christian Channel is available 24 hours a day, 7 days a week on Foxtel, Austar, Optus, TransACT, and Neighbourhood Cable....
(Channel 46) - Expo Home Shopping (Channel 49) and
- Federal parliamentary audio broadcasts.
More recently a near-Australia wide broadcast of a datacasting channel called MyTalk
MyTalk
MyTalk was a Fairfax Media television channel available to viewers of digital television in Australia. The datacast channel, launched on 13 April 2007, was designed to supplement the Southern Cross Ten and Southern Cross Television digital television services and the online portal...
commenced on April 13, 2007. Broadcasting as part of the multiplex on Southern Cross
Southern Cross Television
Southern Cross Television, or Southern Cross, is an Australian television network available in Tasmania, Darwin, Regional South Australia, and Central Australia. Although the programming varies from region to region, all areas are affiliated with the Seven Network and, in some areas, have a dual...
and Southern Cross Ten
Southern Cross Ten
Southern Cross Ten is an Australian television channel broadcast by the Macquarie Media Group in Queensland, New South Wales, the Australian Capital Territory, Victoria and South Australia. The channel is owned by the Macquarie Media Group as is affiliated to Network Ten...
stations, it provided news, weather and other information, available free to anyone able to tune in. The stream consisted of text applicable to the viewer's location and a 4:3 video window of broadcast TV from the relevant Southern Cross
Southern Cross Television
Southern Cross Television, or Southern Cross, is an Australian television network available in Tasmania, Darwin, Regional South Australia, and Central Australia. Although the programming varies from region to region, all areas are affiliated with the Seven Network and, in some areas, have a dual...
/Southern Cross Ten
Southern Cross Ten
Southern Cross Ten is an Australian television channel broadcast by the Macquarie Media Group in Queensland, New South Wales, the Australian Capital Territory, Victoria and South Australia. The channel is owned by the Macquarie Media Group as is affiliated to Network Ten...
station.
On February 25, 2008, MyTalk ceased broadcasting. Digital Forty Four was shut down at exactly midnight on the night of April 30, 2010.
Malaysia
Malaysian multi-channel pay-TV operator, MiTV Corporation Sdn Bhd has launched its IP over UHF service in September 2005. The full digital broadcast capacity is being used to deliver IP services which such as multicast streaming and datacasting.South Africa
Mindset NetworkMindset Network
Mindset Network is a non-profit organisation formed in 2002 to educate and improve health in South Africa. It develops, sources, distributes and uses digital content. Its multimedia content is distributed via broadcast television, IP based satellite datacast, the web, distributable media and...
has developed an IP satellite datacast platform for the distribution of educational and health content to sites around South Africa and increasingly throughout the rest of Africa as well. The model is a forward and store model allowing users of the platform to view content in an on-demand fashion. Content distributed in this way includes video content, print-based content (in the form of PDF files), as well as interactive computer-based multimedia content.
Significantly, the model also includes access to a GPRS network that allows the receiving sites to communicate back to the Mindset central server. Communications include statistics about the physical health of the machine (e.g. power status, disk drive usage) as well as usage statistics indicating what content has been viewed.
The model also includes a distributed deployment of the Moodle
Moodle
Moodle is a free source e-learning software platform, also known as a Course Management System, Learning Management System, or Virtual Learning Environment...
LMS, allowing users to take assessments and then have the results transmitted via GPRS to the Mindset server for accreditation.
United Kingdom
TeletextTeletext
Teletext is a television information retrieval service developed in the United Kingdom in the early 1970s. It offers a range of text-based information, typically including national, international and sporting news, weather and TV schedules...
is used extensively on analogue channels; a type of Datacasting using the Overscan
Overscan
Overscan is extra image area around the four edges of a video image that may not be seen reliably by the viewer. It exists because television sets in the 1930s through 1970s were highly variable in how the video image was framed within the cathode ray tube .-Origins of overscan:Early televisions...
on analogue transmissions. Teletext Limited and Ceefax are the main providers. Within Digital television the Digital Teletext name is used extensively although the technology used to provide this service is unrelated and uses the MHEG-5
MHEG-5
MHEG-5, or ISO/IEC 13522-5, is part of a set of international standards relating to the presentation of multimedia information, standardised by the Multimedia and Hypermedia Experts Group...
UK profile.
See also
- Interactive televisionInteractive televisionInteractive television describes a number of techniques that allow viewers to interact with television content as they view it.- Definitions :...
- DVB-HDVB-HDVB-H is one of three prevalent mobile TV formats. It is a technical specification for bringing broadcast services to mobile handsets. DVB-H was formally adopted as ETSI standard EN 302 304 in November 2004. The DVB-H specification can be downloaded from the official DVB-H website...
- Multimedia home platformMultimedia Home PlatformMultimedia Home Platform is an open middleware system standard designed by the DVB project for interactive digital television. The MHP enables the reception and execution of interactive, Java-based applications on a TV-set. Interactive TV applications can be delivered over the broadcast channel,...
- UDcastUDcastUDcast is a provider of solutions enabling full Internet Protocol over broadcast media, in the areas of IP networks over satellite andservers for DVB-H, DVB-SH, ATSC and WiMAX standards compliant television on mobile networks....
- MPEG Multiprotocol encapsulationMultiprotocol EncapsulationMultiprotocol Encapsulation, or MPE for short, is a Data link layer protocol definedby DVB which has been published as part of ETSI EN 301 192...
- MPEG Unidirectional Lightweight EncapsulationUnidirectional Lightweight EncapsulationThe Unidirectional Lightweight Encapsulation is a Data link layer protocol for the transportation of network layer packets over MPEG transport streams....
External links
- Digital Forty Four (Official Site)
- PBS National Datacast (NDI)