Datacasting often provides news, weather, traffic, stock market, and other information which may or may not relate to the programs 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 DTT, though they do not necessarily define how. The overscan and VBI are used for analog TV, for moderate and low bandwidths respectively. DirectBand and RDS/RBDS are medium and narrow subcarriers 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 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 was approved by the DVB project in October 2005.
Ambient Information Network, a datacasting network owned by Ambient Devices presently hosted by U.S.A. Mobility, a U.S. paging service and focuses on information of interest to the local area, such as weather and stock indices, and with a paid subscription Ambient will provide a particular device with more personalized information.
A slight variation of the European Radio Data System, RBDS is carried on a 57kHz subcarrier on FM radio stations. While originally intended for program-associated data, it can also be used for datacasting purposes including paging and dGPS.
DirectBand
, owned by Microsoft, uses the 67.65 kHz subcarrier leased from FM radio stations. This subcarrier delivers about 12 kbit/s 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.
is an advertising-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.
ATSC-M/H
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. From a technical standpoint, it is an IP-encapsulated datacast of MPEG-4streaming video, alongside the ATSC MPEG transport stream used for terrestrial television broadcasting. Heavy error correction, separate from that native to ATSC, compensates for ATSC's poor mobile reception.
Australian broadcast infrastructure company Broadcast Australia undertook a three-year trial in Sydney of a datacasting service using the DVB-T 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:
A combined program guide for the free-to-air broadcasters
ABC news, sport, and weather items
Channel NSW Government and Public Information, including real time traffic information and life surf webcam images
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 terrestrial 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.
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
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. he 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, 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 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.
United Kingdom
was used extensively on analogue channels; a type of datacasting using the overscan on analogue transmissions. Teletext Limited and Ceefax were the main providers. Within digital terrestrial 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.
Worldwide
Outernet
's goal is to provide free access to content from the web through geostationary and Low Earth Orbit satellites, made available effectively to all parts of the world. The project uses datacasting and User Datagram Protocol through both small satellites, such as CubeSats, and larger, more conventional geostationary communications satellites in a satellite constellation network. Wi-Fi enabled devices would communicate with the satellite hotspots, which receive data broadcasts from satellites.
