Digital Terrestrial Multimedia Broadcast

Last updated

DTMB (Digital Terrestrial Multimedia Broadcast) 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 (Hong Kong and Macau), and also in Cambodia, the Comoros, Cuba, East Timor, Laos and Pakistan. [1] 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". [2]

Contents

Overview

Previously known as DMB-T/H (Digital Multimedia Broadcast-Terrestrial/Handheld), the DTMB is a merger of the standards ADTB-T (developed by the Shanghai Jiao Tong University), DMB-T (developed by Tsinghua University) and TiMi (Terrestrial Interactive Multiservice Infrastructure); this last one is the standard proposed by the Academy of Broadcasting Science in 2002.

At first, neither Shanghai Jiao Tong University nor Tsinghua had enough political strength to make their own technology become the unique standard, so the final decision was to opt for a double standard, merged with the TIMI 3 standard, responding to a need for backward compatibility.

The DTMB was created in 2004 and finally became an official DTT standard in 2006.

DTMB in China

DTMB channel available in China

Main channel of province TV in each province

DTMB in Hong Kong

DTMB in Macau

DTMB elsewhere

Versus CMMB

See China Multimedia Mobile Broadcasting (CMMB).

Countries and territories using DTMB

DTT broadcasting systems. Countries using DTMB are shown in purple. Digital broadcast standards.svg
DTT broadcasting systems. Countries using DTMB are shown in purple.

Asia

Caribbean

Africa

Description

Besides the basic functions of traditional television service, the DTMB allows additional services using the new television broadcasting system. DTMB system is compatible with fixed reception (indoor and outdoor) and mobile digital terrestrial television.

Modulation

The DTMB standard uses many advanced technologies to improve their performance, for example, a pseudo-random noise code (PN) as a guard interval that allows faster synchronization system and a more accurate channel estimation, Low-Density Parity Check (LDPC) for error correction, modulation Time Domain Synchronization - Orthogonal Frequency Division Multiplexing (TDS-OFDM) which allows the combination of broadcasting in SD, HD and multimedia services, etc.

This system gives flexibility to the services offered to support the combination of single-frequency networks (SFN) and multi-frequency networks (MFN). The different modes and parameters can be chosen depending on the type of service and network's environment.

The sequence of pseudo-random pattern is defined in time domain and the information of the Discrete Fourier transform (DFT) is defined in the frequency domain. The two frames are multiplexed in the time domain, resulting in Time domain synchronization (TDS).

Functional scheme

This transmission system makes the conversion of the input signal to the output data of terrestrial TV signal.

The data passes through the encoder, the error protection process FEC (Forward Error Correction), through the constellation mapping process and then the interleaving processes the information to create the data blocks. The data block and the TPS information are multiplexed, and pass through the data processor to form the body structure. It combines information from the body and the head to form the frame and this is passed through the SRRC (Square Root Raised Cosine) filter to become a signal within an 8 MHz channel bandwidth. Finally the signal is modulated to put it in the corresponding frequency band.

Features

See also

Related Research Articles

Digital television transmission of television audiovisual signals 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 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).

Terrestrial television Television content transmitted via signals in the air

Terrestrial television is a type of television broadcasting in which the television signal is transmitted by radio waves from the terrestrial (Earth-based) transmitter of a television station to a TV receiver having an antenna. The term terrestrial is more common in Europe and Latin America, while in the United States it is called broadcast or over-the-air television (OTA). The term "terrestrial" is used to distinguish this type from the newer technologies of satellite television, in which the television signal is transmitted to the receiver from an overhead satellite; cable television, in which the signal is carried to the receiver through a cable; and Internet Protocol television, in which the signal is received over an Internet stream or on a network utilizing the Internet Protocol. Terrestrial television stations broadcast on television channels with frequencies between about 52 and 600 MHz in the VHF and UHF bands. Since radio waves in these bands travel by line of sight, reception is generally limited by the visual horizon to distances of 64–97 kilometres (40–60 mi), although under better conditions and with tropospheric ducting, signals can sometimes be received hundreds of kilometers distant.

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.

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.

Television in Hong Kong is primarily in Cantonese and English. It is delivered through analogue and digital terrestrial, cable, IPTV, and the Internet. Satellite TV is not common, although many housing estates have dishes and re-distribute a limited number of free channels through coaxial cables. The dominant broadcaster is TVB.

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.

Digital terrestrial television in the United Kingdom encompasses over 100 television, radio and interactive services broadcast via the United Kingdom's terrestrial television network and receivable with a standard television set. The majority of digital terrestrial television (DTT) services, including the five former analogue channels, are broadcast free-to-air, and a further selection of encrypted pay TV services are also available.

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.

DVB-T2 is an abbreviation for "Digital Video Broadcasting — Second Generation Terrestrial"; it is the extension of the television standard DVB-T, issued by the consortium DVB, devised for the broadcast transmission of digital terrestrial television. DVB has been standardized by ETSI.

China Mobile Multimedia Broadcasting (CMMB) is a mobile television and multimedia standard developed and specified in China by the State Administration of Radio, Film, and Television (SARFT). It is based on the Satellite and Terrestrial Interactive Multiservice Infrastructure (STiMi), developed by TiMiTech, a company formed by the Chinese Academy of Broadcasting Science. Announced in October 2006, it has been described as being similar to Europe's DVB-SH standard for digital video broadcast from both satellites and terrestrial repeaters to handheld devices.

In Malaysia, digital television broadcasts, DTV or DHD, can be received via cable, internet, satellite, or via free over-the-air (OTA) digital terrestrial television - much like analogue television broadcasts have been. It began in the mid-1990s with the introduction of the Astro satellite television service, now followed by new paid television services in the 2000s, as well as the digitalisation of over-the-air TV which was expected to be complete by the mid-2010s before being shelved. This article discusses various platforms where DTV is applied in Malaysia, including Digital Video Broadcasting (DVB) and Internet Protocol Television (IPTV). Following its successful nationwide digital transition on 31 October 2019, the country became the third in Southeast Asia with digital broadcasts after neighbouring Brunei and Singapore.

Digital terrestrial television in the Philippines are in development by the Philippine major broadcasting companies.

Digital television transition Global switchover to digital television

The digital television transition, also called the digital switchover (DSO), the analog switch-off (ASO), the digital migration, or the analog shutdown, is the process in which older analog television broadcasting technology is converted to and replaced by digital television. Conducted by individual nations on different schedules, this primarily involves the conversion of analog terrestrial television broadcasting infrastructure to digital terrestrial (DTT), a major benefit being extra frequencies on the radio spectrum and lower broadcasting costs, as well as improved viewing qualities for consumers.

Saorview is the national digital terrestrial television (DTT) service in Ireland. It is owned by RTÉ and operated by 2RN.

Digital multimedia broadcasting The South Korean digital TV standard

Digital multimedia broadcasting (DMB) is a digital radio transmission technology developed in South Korea 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 which was developed as a research project for the European Union. DMB was developed in South Korea as the next generation digital technology to replace FM radio, but the technological foundations were laid by Prof. Dr. Gert Siegle and Dr. Hamed Amor at Robert Bosch GmbH in Germany. 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 the main competing mobile TV standard, DVB-H.

References

  1. http://www.cpec.gov.pk/project-details/41
  2. http://www.digitaltvnews.net/?p=29171
  3. 1 2 3 4 5 6 7 DTV Status. Retrieved May 30, 2012
  4. "Government to switch off analogue television services at end-November 2020" . Retrieved 30 May 2019.CS1 maint: discouraged parameter (link)
  5. http://annx.asianews.network/content/media-laos-moves-forward-digitalisation-despite-challenges-56706
  6. http://www.chinadaily.com.cn/m/beijing/zhongguancun/2012-11/29/content_15974934.htm
  7. https://en.indian-ocean-times.com/Comoros-choose-the-Chinese-standard-for-the-deployment-of-digital-terrestrial-television-in-June-2015_a3752.html
  8. https://advanced-television.com/2013/03/22/cuba-adopts-chinese-tv-standard/
  9. https://www.zte.com.cn/global/about/news/0515ma
  10. http://tl.chineseembassy.org/eng/xwdt/t1674432.htm
  11. CNTV English Archived 2013-03-22 at the Wayback Machine . Retrieved March 21, 2013

Further reading