DMB-T/H

DMB-T/H or DTMB (GB 20600-2006) is the digital terrestrial television (DTT) standard applied in the People's Republic of China (PRC), including Hong Kong and Macau. This mandatory standard will cover both fixed and mobile terminals and will eventually serve more than half of the television viewers in the PRC, especially those in suburban and rural areas.

Overview

The standard is being officially called Digital Terrestrial Multimedia Broadcast (abbreviated as DTMB. The standard was formerly named as Digital Multimedia Broadcast-Terrestrial/Handheld and in short DMB-T/H). DTMB is an outgrowth of work at Jiaotong University (developed ADTB-T, similar to ATSC, which coexists with DVB-T) in Shanghai and Tsinghua University (developed DMB-T, similar to T-DMB) in Beijing, each of which had hoped to provide the sole technology – but neither of which had the technical or political muscle to achieve that goal, the final decision was to opt for a dual standard and fuse with the TiMi 3 standard, as a direct result of backward compatibility as the exploitation of ADTB-T, DMB-T and DVB-T for HDTV transmission via set-top boxes occurred prior to the final draft of the standard, thus making DTMB a fusion of the two aforementioned standards, the ADTB-T and DMB-T.

The data transmission methodology implemented by the standard is the TDS-OFDM^[1] (short for "Time Domain Synchronuous-Orthogonal frequency-division multiplexing"), which mainly is a multiple-carrier modulation technology, supporting both single-carrier and dual-carrier modulation schemes. The standard, according to the co-developer of the DMB-T standard with Tsing Hua University, is capable of transmitting "acceptable" signal qualities for the HDTV receiver to be moving at 200 km/h speed. The standard also has the support of mobile digital TV service on handhelds which is absent from typical digital TV implementations in Europe and America. In addition to these, the radius of the area with signal coverage using the DTMB standard is 10 km longer than the European implementation, the DVB-T standard. The standard also has the advantages of the three standards, DVB-T, ADTB-T and TiMi 3 as the DTMB standard is the fusing of the three technologies.

Despite the advantages, there are also short comings of the standard. As the standard supports both, single-carrier and dual-carrier modulation schemes as well as not defining the default video encoding standards, the R&D cost and complexity of the chip IC for this standard will be increased, leading to more expensive receiver products. In addition, TV programs bought from overseas which are broadcast in digital TV format may have to do a signal conversion that suits the DTMB environment, as the DTMB standard is slightly different than the original DVB-T and ATSC standards, which is less cost effective.

It is worth to note in spite of the data transmission methodology of the standard being set, the standard itself does not restrict broadcasters to certain number of video codecs to be used in transmitting digital TV signals, that each individual broadcasters have the discretion to utilize any of the video codecs that supports high-definition video, as well as the systems providing subtitles, Electronic Programme Guides and interactive features.

Versus CMMB

See China Multimedia Mobile Broadcasting (CMMB).

Countries and territories using DTMB

Asia

•  People's Republic of China
•  Hong Kong
•  Macau
•  Iraq (Experimental)
•  Jordan (Experimental)
•  Syria (Experimental)

South America

•  Nicaragua (Experimental)
•  Cuba (Experimental)
•  Ecuador (Experimental)
•  Bolivia (Experimental)

DTT broadcasting systems. Countries using DMB-T/H are shown in red.

Mainland China

The PRC government announced the final approval of the standard on August 1, 2007. All video contents of the 2008 Beijing Olympics was broadcasted in high-definition (720p or 1080i) using the DMB-T standard.

Hong Kong SAR

Digital broadcasts in Hong Kong began at 7 p.m. on December 31, 2007. Both air TV stations began to broadcast in both analog and digital. It was hoped that most people in Hong Kong will be able to watch the Olympics in August through digital signal. At some point in time, a total of 8 digital channels (including 4 which duplicate the analog channels) were broadcasting the Olympics at the same time.

Further reading

• Kumar, Amitabh (2007). Mobile TV: DVB-H, DMB, 3G Systems and Rich Media Applications. Focal Press Media Technology Professional Series. Focal Press. ISBN 978-0-240-80946-5. 

See also

• CMMB
• OFDM system comparison table
• Media in the People's Republic of China
• Communications in the People's Republic of China
• Telecommunications industry in China
• Digital television in China (PRC)
• Technical standards in colonial Hong Kong
• Digital terrestrial television
• ATSC Standards- Advanced Television Systems Committee Standard
• DVB-T - Digital Video Broadcasting--Terrestrial
• ISDB - Integrated Services Digital Broadcasting

References

External links

• IEEE Spectrum - Does China Have the Best Digital Television Standard on the Planet?
• (Chinese) Information page of the standard on Standardization Administration of PRC site
• (Chinese) Official announcement of intent to approve the standard on August 1, 2007 made by Standardization Administration of PRC
• (Chinese) ChineseNewsNet report
• (Chinese) C|Net China report
• Hong Kong Technical Standard for Digital Terrestrial Television Broadcasting
• MING-T, Multistandard Integrated Network convergence for Global Mobile and Broadcast Technologies
• (Spanish) Venezuela starts trials DTMB