World TV standards
Oct 1, 2007 12:00 PM, BY ALDO CUGNINI
ATSC, ISDB-T, DVB-T and DMB-T/H stake their claims.
DTMB
The Chinese government has developed a proprietary system, now called DTMB, for Digital Terrestrial Multimedia Broadcasting. Incorporating MPEG2 systems with video coding provisionally similar to MPEG-4/AVC, the transmission scheme features a layered frame structure synchronized with real time, a function developed for power saving. Single-carrier and multicarrier operation are possible, and four-level through 64-level QAM are supported.
Switchoff
The analog broadcasting switchoff varies by implementing country. Berlin-Brandenburg became the first region in the world to switch off its terrestrial analog signals in August 2003. In December 2006, the Netherlands was the first country to do so. In the United States, the analog switchoff is slated for February 2009, and while there has been some noise about possible delays, the push to free spectrum for “first responders” and emergency uses — together with pending spectrum auctions and the Federally mandated converter box program — most assuredly freezes that date. The switchoff of Japanese analog broadcasting — mandated by the Radio Law — is scheduled for 2011.
Conclusion
The variation in world digital TV standards is, for the most part, one of transmission system, with scanning formats now of lesser consequence, especially with the profusion of digital signal processing. While the promise of a universal TV system may have to await future developments, the display and storage of video have come closer to a ubiquitous norm.
Aldo Cugnini is a consultant in the digital television industry.
Send questions and comments to: aldo.cugnini@penton.com
| Region | Transmission | Transport | Video | Audio | |
|---|---|---|---|---|---|
| Africa | South Africa | DVBT | MPEG2 | MPEG2 | MPEG2 |
| Asia | China | DTMB | MPEG2 | MPEG2 or AVS-China | MPEG2 or AVS-China |
| India | DVBT | MPEG2 | MPEG2 | MPEG2 | |
| Japan | ISDBT | MPEG2/AAC | |||
| Russia | DVBT | MPEG2 | |||
| South Korea | ATSC | AC-3 | |||
| Australia | DVBT | MPEG2 | MPEG2 | MPEG2, AC-3 | |
| Europe | DVBT | MPEG2 | MPEG2 | MPEG2 | |
| North America | Canada | ATSC | MPEG2 | MPEG2 | AC-3 |
| Mexico | |||||
| United States | |||||
| South America | Argentina | ATSC | MPEG2 | MPEG2 | AC-3 |
| Brazil | ISDBT | MPEG2/AAC | |||
| Honduras | ATSC | AC-3 | |||
| System | ATSC | DVBT | ISDBT | DTMB |
|---|---|---|---|---|
| Proposing region | United States | Europe | Japan | China |
| Transmission | Single carrier | Multiple carrier (OFDM) | | Single carrier (QAM)/Multiple carrier (OFDM) |
| Bandwidth | 6MHz/7MHz/8MHz | 6MHz/7MHz/8MHz | | 8MHz |
| Modulation | 8-VSB | QPSK/16-QAM/64-QAM | DQPSK/QPSK/16QAM/64QAM | 4QAM/16QAM/32QAM/64QAM |
| Error correction | Trellis code + RS | Convolution code + RS | | BCH code + LDPC code |
| Characteristic | Distributed-transmission capability | SFN capability | SFN capability, segmented OFDM, time interleaving | Time interleaving, frequency interleaving |
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