Digital multimedia broadcasting

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Live DMB broadcast on an iriver device during trials in Munich, Germany (2007) Live television on this iRiver DAB DMB device.jpg
Live DMB broadcast on an iriver device during trials in Munich, Germany (2007)
A DMB television broadcast received on a mobile device in South Korea DMB Phone.jpg
A DMB television broadcast received on a mobile device in South Korea

Digital multimedia broadcasting (DMB) is a digital radio transmission technology developed in South Korea [1] [2] [3] as part of the national IT project for sending multimedia such as TV, radio and datacasting to mobile devices such as mobile phones, laptops and GPS navigation systems. This technology, sometimes known as mobile TV, should not be confused with Digital Audio Broadcasting (DAB) which was developed as a research project for the European Union.

Contents

DMB was developed in South Korea as the next generation digital technology to replace FM radio, [4] but the technological foundations were laid by Prof. Dr. Gert Siegle and Dr. Hamed Amor at Bosch in Germany. [5] The world's first official mobile TV service started in South Korea in May 2005, although trials were available much earlier. It can operate via satellite (S-DMB) or terrestrial (T-DMB) transmission. DMB has also some similarities with its former competing mobile TV standard, DVB-H. [6]

S-DMB

T-DMB

T-DMB is made for terrestrial transmissions on band III (VHF) and L (UHF) frequencies. DMB is unavailable in the United States because those frequencies are allocated for television broadcasting (VHF channels 7 to 13) and military applications. USA is adopting ATSC-M/H for free broadcasts to mobiles, and Qualcomm's proprietary MediaFLO system was used there. In Japan, 1seg is the standard, using ISDB.

T-DMB uses MPEG-4 Part 10 (H.264) for the video and MPEG-4 Part 3 BSAC or HE-AAC v2 for the audio. The audio and video is encapsulated in an MPEG transport stream (MPEG-TS). The stream is forward error corrected by Reed Solomon encoding and the parity word is 16 bytes long. There is convolutional interleaving made on this stream, then the stream is broadcast in data stream mode on DAB. In order to diminish the channel effects such as fading and shadowing, the DMB modem uses OFDM-DQPSK modulation. A single-chip T-DMB receiver is also provided by an MPEG transport stream demultiplexer. DMB has several applicable devices such as mobile phone, portable TV, PDA and telematics devices for automobiles.

T-DMB is an [ETSI] standard (TS 102 427 and TS 102 428). As of December 14, 2007, ITU formally approved T-DMB as the global standard, along with three other standards, like DVB-H, 1seg, and MediaFLO. [7]

Smart DMB

Smart DMB started in January 2013 in South Korea. Smart DMB has a VOD service and quality has been improved from 240p to 480p. Smart DMB is built in many Korean smartphones starting with the Galaxy Grand in January 2013. [8]

HD DMB

HD DMB started in August 2016 in South Korea. HD DMB has been improved from 240p to 720p. It uses HEVC.5 codec. There are currently 6 HD DMB stations in Seoul. Smartphones integrated Qualcomm Snapdragon 801 or higher received firmware upgrade to support HD DMB.

Countries using DMB

Currently, DMB is being put into use in a number of countries, although mainly used in South Korea. Also see list of Countries using DAB/DMB.

South Korea

In 2005, South Korea became the world's first country to start S-DMB and T-DMB service on May 1 and December 1, respectively. [9] [10] In December 2006, T-DMB service in South Korea consists of, 7 TV channels, 12 radio channels, and 8 data channels. These are broadcast on six multiplexes in the VHF band on TV channels 8 and 12 (6 MHz raster). In October 2007, South Korea added broadcasting channel MBCNET to the DMB channel. But in 2010, this channel changed tnN go. In 2009 there were eight DMB video channels in Seoul, and six in other metropolitan cities. As of April 2013, S-DMB service in South Korea consists of 15 TV channels, 2 radio channels and 6 data channels. [11]

South Korea has had Full T-DMB services including JSS (Jpeg Slide Show), DLS (Dynamic Label Segment), BWS, and TPEG since 2006.

S-DMB service in South Korea is provided on a subscription basis through TU Media and is accessible throughout the country. T-DMB service is provided free of charge, but access is limited to selected regions.

Around one million receivers have been sold as of June 2006. 14 million DMB receivers were sold including T-DMB and S-DMB in South Korea, and 40% of the new cell phones have the capability to see DMB. [12]

Receivers are integrated in car navigation systems, mobile phones, portable media players, laptop computers and digital cameras. In mid-August 2007, Iriver, a multimedia and micro-technology company released their "NV", which utilizes South Korea's DMB service.

Since the advent of smartphones DMBs have been made available on phones with receivers through smartphone applications, most of which come pre-installed in phones made and sold in Korea.

Other countries

Some T-DMB trials are currently available or planned around Europe and other countries:

DMB in automobiles

T-DMB works flawlessly in vehicles traveling up to 300 km/h.[ citation needed ] In tunnels or underground areas, both television and radio broadcast is still available, though DMB may skip occasionally. In South Korea, some long-distance buses adopted T-DMB instead of satellite TV such as Sky TV. It works quite well even though the resolution is 240p, lower than satellite. In comparison, satellite is usually 480p or higher.[ citation needed ]

See also

Related Research Articles

Digital television television transmission using digital encoding

Digital television (DTV) is the transmission of television audiovisual signals using digital encoding, in contrast to the earlier analog television technology which used analog signals. At the time of its development it was considered an innovative advancement and represented the first significant evolution in television technology since color television in the 1950s. Modern digital television is transmitted in high definition (HDTV) with greater resolution than analog TV. It typically uses a widescreen aspect ratio in contrast to the narrower format of analog TV. It makes more economical use of scarce radio spectrum space; it can transmit up to seven channels in the same bandwidth as a single analog channel, and provides many new features that analog television cannot. A transition from analog to digital broadcasting began around 2000. Different digital television broadcasting standards have been adopted in different parts of the world; below are the more widely used standards:

Digital audio broadcasting Digital radio standard

Digital audio broadcasting (DAB) is a digital radio standard for broadcasting digital audio radio services in many countries around the world, defined and promoted by the WorldDAB forum. The standard is dominant in Europe and is also used in parts of Africa, Asia and Australia; other worldwide terrestrial digital radio standards include HD Radio, ISDB-Tb, DRM, and the related DMB.

Digital Video Broadcasting open standard for digital television broadcasting

Digital Video Broadcasting (DVB) is a set of international open standards for digital television. DVB standards are maintained by the DVB Project, an international industry consortium, and are published by a Joint Technical Committee (JTC) of the European Telecommunications Standards Institute (ETSI), European Committee for Electrotechnical Standardization (CENELEC) and European Broadcasting Union (EBU).

DVB-T, short for Digital Video Broadcasting — Terrestrial, 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 Singapore in February, 1998. This system transmits compressed digital audio, digital video and other data in an MPEG transport stream, using coded orthogonal frequency-division multiplexing modulation. It is also the format widely used worldwide for Electronic News Gathering for transmission of video and audio from a mobile newsgathering vehicle to a central receive point. It is also used in the US by Amateur television operators.

The Integrated Services Digital Broadcasting is a Japanese standard for digital television (DTV) and digital radio used by the country's radio and television networks. ISDB supersedes both the NTSC-J analog television system and the previously used MUSE Hi-vision analog HDTV system in Japan as well as the NTSC, PAL-M, and PAL-N broadcast standards in South America and the Philippines. Digital Terrestrial Television Broadcasting (DTTB) services using ISDB-T started in Japan in December 2003 and Brazil in December 2007 as a trial. Since then, many countries have adopted ISDB over other digital broadcasting standards.

Advanced Television Systems Committee (ATSC) standards are an American set of standards for digital television transmission over terrestrial, cable and satellite networks. It is largely a replacement for the analog NTSC standard and, like that standard, is used mostly in the United States, Mexico, Canada, and South Korea. Several former NTSC users, in particular Japan, have not used ATSC during their digital television transition, because they adopted their own system called ISDB.

Digital Radio Mondiale Digital radio broadcasting standard

Digital Radio Mondiale is a set of digital audio broadcasting technologies designed to work over the bands currently used for analogue radio broadcasting including AM broadcasting, particularly shortwave, and FM broadcasting. DRM is more spectrally efficient than AM and FM, allowing more stations, at higher quality, into a given amount of bandwidth, using xHE-AAC audio coding format. Various other MPEG-4 and Opus codecs are also compatible, but the standard now specifies xHE-AAC.

Digital radio is the use of digital technology to transmit or receive across the radio spectrum. Digital transmission by radio waves includes digital broadcasting, and especially digital audio radio services.

Digital terrestrial television is a technology for terrestrial television in which land-based (terrestrial) television stations broadcast television content by radio waves to televisions in consumers' residences in a digital format. DTTV is a major technological advance over the previous analog television, and has largely replaced analog which had been in common use since the middle of the 20th century. Test broadcasts began in 1998 with the changeover to DTTV beginning in 2006 and is now complete in many countries. The advantages of digital terrestrial television are similar to those obtained by digitising platforms such as cable TV, satellite, and telecommunications: more efficient use of limited radio spectrum bandwidth, provision of more television channels than analog, better quality images, and potentially lower operating costs for broadcasters.

Malaysian television broadcasting was introduced on 28 December 1963. Colour television was introduced on 28 December 1978. Full-time colour transmissions were officially inaugurated on New Year's Day 1982. There are currently 8 national free-to-air terrestrial television stations in Malaysia and 2 national pay subscription television stations in Malaysia.

Datacasting is the broadcasting of data over a wide area via radio waves. It most often refers to supplemental information sent by television stations along with digital terrestrial 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 channels for DTT or direct broadcast satellite systems; or to things like cable modem or satellite modem, which use a completely separate channel for data.

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. From March 2008, DVB-H is officially endorsed by the European Union as the "preferred technology for terrestrial mobile broadcasting". The major competitors of this technology are Qualcomm's MediaFLO system, the 3G cellular system based MBMS mobile-TV standard, and the ATSC-M/H format in the U.S. DVB-SH now and DVB-NGH in the future are possible enhancements to DVB-H, providing improved spectral efficiency and better modulation flexibility. DVB-H has been a commercial failure, and the service is no longer on-air. Ukraine was the last country with a nationwide broadcast in DVB-H.

S-DMB (Satellite-DMB) was a hybrid version of the Digital Multimedia Broadcasting. The S-DMB used the S band (2170-2200 MHz) of IMT-2000. and delivered around 18 channels at 128 kbit/s in 15 MHz. It incorporated a high power geostationary satellite, the MBSat 1. For outdoor and light indoor coverage is integrated with a terrestrial repeater network for indoor coverage in urban areas.

Mobile television Television for handheld or mobile device

Mobile television is television watched on a small handheld or mobile device. It includes service delivered via mobile phone networks, received free-to-air via terrestrial television stations, or via satellite broadcast. Regular broadcast standards or special mobile TV transmission formats can be used. Additional features include downloading TV programs and podcasts from the Internet and storing programming for later viewing.

DTMB is the digital TV standard for mobile and fixed devices, developed in the People's Republic of China. It is used there and in both of their special administrative regions, and also in Cambodia, the Comoros, Cuba, East Timor, Laos and Pakistan. In Pakistan, as part of the China–Pakistan Economic Corridor Project, ZTE Corporation will provide Pakistan Television Corporation collaboration across several digital terrestrial television technologies, staff training and content creation including partnerships with Chinese multinational companies in multiple areas including television sets and set top boxes as a form of "International Cooperation".

IP over DVB implies that Internet Protocol datagrams are distributed using some digital television system, for example DVB-H, DVB-T, DVB-S, DVB-C or their successors like DVB-S2. This may take the form of IP over MPEG, where the datagrams are transferred over the MPEG transport stream, or the datagrams may be carried in the DVB baseband frames directly, as in GSE.

ETSI Satellite Digital Radio describes a standard of satellite digital radio. It is an activity of the European standardisation organisation ETSI.

Countries using DAB/DMB

The radio technology known as Digital Audio Broadcasting, and its TV sibling, Digital Multimedia Broadcasting (DMB), is being operated in several regions worldwide, either in the form of full services, or as feasibility studies.

References

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