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List of digital television broadcast standards
DVB family (Europe)
DVB-S (satellite)
DVB-T (terrestrial)
DVB-C (cable)
DVB-H (handheld)
ATSC family (North America)
ATSC (terrestrial/cable)
ATSC-M/H (mobile/handheld)
ISDB family (Japan/Brazil)
ISDB-S (satellite)
ISDB-T (terrestrial)
ISDB-C (cable)
SBTVD/ISDB-Tb (Brazil)
Chinese Digital Video Broadcasting standards
DMB-T/H (terrestrial/handheld)
ADTB-T (terrestrial)
CMMB (handheld)
DMB-T (terrestrial)
DMB Family (Korean handheld)
T-DMB (terrestrial)
S-DMB (satellite)
MediaFLO
Codecs
Video
Audio
Frequency bands
VHF
UHF
SHF

DMB-T/H or DTMB (GB 20600-2006) is the digital terrestrial television (DTT) standard adopted in the People's Republic of China (PRC), including Hong Kong and Macau. This mandatory standard covers 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.

Contents

Overview

The standard is officially called Digital Terrestrial Multimedia Broadcast (abbreviated as DTMB). The standard was formerly named Digital Multimedia Broadcast-Terrestrial/Handheld (abbreviated as 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. Both hoped to provide the sole technology, but neither had the technical or political muscle to achieve that goal. The final decision was to opt for a dual standard and fuse it with the TiMi 3 standard. This was a direct result of a need for backward compatibility, because the adoption of ADTB-T, DMB-T and DVB-T for HDTV transmissions via set-top boxes occurred prior to the final draft of the standard. Therefore, DTMB became a fusion of the two aforementioned standards, ADTB-T and DMB-T.

The data transmission methodology implemented by the standard is TDS-OFDM[1] (short for "Time Domain Synchronuous-Orthogonal frequency-division multiplexing"), which is primarily a multiple-carrier modulation technology, supporting both single-carrier and dual-carrier modulation schemes. According to the co-developer of the DMB-T standard at Tsing Hua University, the standard is capable of transmitting "acceptable" signal quality for HDTV receivers moving at speeds up to 200 km/h. The standard also supports mobile digital TV service on handhelds, a feature absent from typical digital TV implementations in Europe and America. In addition, the radius of the signal coverage area is 10 km greater than the European implementation, the DVB-T standard. As a fusion of three standards (DVB-T, ADTB-T and TiMi 3), the DTMB standard provides many of the advantages of each..

Despite the advantages, there are also shortcomings. Because the standard supports both single-carrier and dual-carrier modulation schemes, and because it does not define default video encoding standards, the R&D cost and complexity of IC chipsets for this standard will be higher, 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 noting that, even though it specifies a data transmission methodology, the standard does not restrict broadcasters to a certain number of video codecs to be used in transmitting digital TV signals. Broadcasters have the discretion to utilize any video codec that supports high-definition video, as well as systems for providing subtitles, Electronic Programme Guides and interactive features.

Versus CMMB

See China Multimedia Mobile Broadcasting (CMMB).

Countries and territories using DTMB

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Asia

Americas

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

References

  1. ^ (Chinese) Tsing Hua University coverage, retrieved October 18, 2007

External links


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