I think this reporter cut and pasted parts of a past story into this one
and got it wrong. China was going to go with a dual standard but took
some time and come up with a compromise which incorporates some of the
VSB stuff but is still a multi-carrier TD-OFDM modulation. Broadcasters
are not going to be using a single carrier for rural areas and a
multi-carrier for cities. I think the VSB part is more face saving to
get this done. Notice no one is talking about dual receivers or
broadcasters having to chose what modulation to use anymore which they
were doing in the summer.
I thought it would have been interesting to see them go head to head and
was disappointed when they compromised. The VSB had mobile test in one
city and fixed in some others but the DMB-T test were taking place in 30
or more cities. If they had gone head to head no one would have
implemented the VSB. As it is I don't think you will find any help from
whatever was grafted onto the DMB-T from VSB to make it CDMB-T/H. Would
like to know what it is though. I think the VSB side caved because they
knew that if they didn't win it all and were part of a dual standard
they were history. Same as would have happened if Sinclair had been
successful in getting COFDM allowed in the US. 8-VSB advocates fought
very hard against that because they knew that 8-VSB stood no chance
against DVB-T.
Though I think the VSB system in China was far better than what we have
and it would be great if we could use it here.
Bob Miller
Some time ago, I posted an article which explained that the Chinese DTV standard was developed by two universities, one which developed a VSB scheme, the other a time-synchronous COFDM scheme. The two were merged into one standard. It looks like this combined standard has been approved.
The new aspect of this story is that, apparently, the VSB portion of the standard must be used for fixed reception, and the COFDM portion, which seems to be only time-divided COFDM, is only meant for portable handheld devices. I hadn't gotten this impression last time, but it makes sense if the COFDM part of the standard is only for time-synchronous transmissions (a la DVB-H, is my assumption). Here's the quote:
"The resulting spec is less a combination of the universities' work than a coexistence of two modulation schemes--Tsinghua's time-domain synchronous orthogonal frequency-division multiplexing and Jiaotong's vestigial sideband modulation. Jiaotong's technology will be used for broadcasts to fixed TVs; Tsinghua's technology will be more suitable for mobile terminals in urban settings."
The good news for ATSC, I think, is that this means that many more smart people will be looking for equalizer and tuner technology improvements aimed specifically at VSB reception. What's more, the manufacturers designing and building VSB receivers for the Chinese home market will likely also be building ATSC receivers. At least some of their innovations will probably also be applicable to ATSC.
Bert
------------------------------- China OKs its own terrestrial DTV spec
Mike Clendenin (09/04/2006 9:00 AM EDT) URL: http://www.eetimes.com/showArticle.jhtml?articleID=192500943
Shanghai, China -- China's standards body gave the thumbs-up to a homegrown terrestrial digital-TV technology last week, saying broadcasts would begin next August. The decision clears the path for China's effort to transition hundreds of millions of households to free-to-air digital broadcasts. But it leaves a fuzzy picture for the mobile-TV segment, where a handful of standards still compete.
China wants to see widespread use of digital TV by the 2008 Summer Olympics in Beijing. For televisions, that will be easier to do. A few chip makers, armed with early drafts of the standard, known as Digital Multimedia Broadcast-Terrestrial/Handheld, are already putting the finishing touches on silicon and reference designs, and they are confident about winning design-ins for set-top boxes, personal media players and notebook PCs (via USB dongles) by later this fall.
But there is uncertainty about whether DMB-T/H will be ready for the small screens of handsets by the Olympics. That could leave the door open to competing specs, such as Europe's DVB-Handheld, the MediaFLO format pitched by Qualcomm Inc., and two formats announced in China in recent weeks: Terrestrial-Mobile Multimedia Broadcasting, a derivative of South Korea's Terrestrial-Digital Multimedia Broadcasting, and STiMi (short for satellite and terrestrial interaction multimedia). The T-MMB and STiMi camps plan to vie for a shot to prove their worth at the 2008 Games.
The DMB-T/H camp has a handset prototype, "but it is in the very early stages," said Xingjun Wang, a Tsinghua University professor who had a hand in hammering out the standard. "For commercial-grade [versions], we still need a low-power chip set, and that is under design. So it will not be easy to make that [Olympics] deadline, if you also consider the testing and certifications that are needed."
Two days after China approved the standard, Analog Devices Inc. and Legend Silicon said they would team up for a three-chip DMB-T/H solution comprising a tuner and Blackfin decoder from ADI and a demodulator from Legend. While clam-shell-style-phone support may be a ways off, ADI is optimistic that the higher levels of integration needed for bulkier smart phones will happen this winter, with hardware prototypes emerging next summer.
"It will be in plenty of time for people to say 'Yep, it works', then kick over to mass production so there can be millions of units in the market for Chinese New Year 2008," said Dave Robertson, product line director for high-speed signal processing at ADI.
Unlike Europe's distinct flavors for DVB--one for terrestrial, one for handheld--China's DMB-T/H was designed for both fixed and mobile terminals and will eventually serve more than half of China's TV viewers, especially those in suburban and rural areas. DMB-T/H is an outgrowth of work at Tsinghua University (Beijing) and Jiaotong University (Shanghai), each of which had hoped to forge the sole technology, but neither of which had the technological or political muscle to pull it off.
The resulting spec is less a combination of the universities' work than a coexistence of two modulation schemes--Tsinghua's time-domain synchronous orthogonal frequency-division multiplexing and Jiaotong's vestigial sideband modulation. Jiaotong's technology will be used for broadcasts to fixed TVs; Tsinghua's technology will be more suitable for mobile terminals in urban settings. China will deploy digital TV over VHFIII and UHF spectrum ranges using an 8-MHz channel bandwidth.
Offshore-based chip companies that have expressed interest in the Chinese standard thus far include ADI, STMicroelectronics and Conexant. Legend has had an inside track on the spec because of its close relationship with Tsinghua University, which is an investor, and so has Shanghai High Definition Digital Technology, which is affiliated with Jiaotong University. Other Chinese companies designing chips for DMB-T/H include Hangzhou-based Guoxin Technology and Shanghai-based Chinips Electronics. In handhelds, Microtune said it plans to expand its mobile tuner product line to include DMB-T/H.
Some set-top-box makers and TV manufacturers, including Haier, Samsung and LG, have turned out prototypes based on DMB-T/H. Trials for fixed TVs and nomadic TVs have been ongoing for at least two years in more than 30 Chinese cities.
By 2008, Tsinghua's Wang expects that DMB-T/H (whose name is being changed to CDMB-T/H to reflect the standard's Chinese origins) will be established in fixed TVs and nomadic terminals of the type used in taxis and trains. But so far only China Putian has a prototype of a handset supporting the spec.
That should leave the door open for T-DMB, a South Korean digital multimedia broadcast standard that is being heavily promoted in China and already is in trials, said ADI's Robertson. "If all the other standards sputtered, and China needed something to deploy in volume with the lowest risk, it would be T-DMB," he said.
DMB-T/H is theoretically more technologically compatible with Europe's DVB-H than with the Korean format; for instance, DMB-T/H and DVB-H use 8-MHz channel widths, vs. 1 MHz for T-DMB. But early lobbying by South Korean interests is giving that country's spec a solid foothold in China.
"DVB-H is probably not going to be used here," said Wilbert Zou, an analyst at Beijing-based telecom consultancy BDA Research. "The picture is also uncertain for Qualcomm's MediaFLO."
Decisions on standards adoption are heavily influenced by China's State Administration of Radio Film and Television, which favors DMB-T/H and T-DMB over DVB-H and MediaFLO. That doesn't bode well for the latter two, though in China's opaque decision-making process fortunes can quickly turn.
Last month's rollouts of the T-MMB and STiMi mobile-TV technologies only complicate matters. Few technical details are available for the new formats, which are supported by academic-industrial coalitions in China.
T-MMB was jointly developed by Beijing-based software firm Nufrontsoft, China's Communication University, and Southeast University. It is supposedly compatible with Digital Audio Broadcasting (DAB)-based T-DMB. The spec supports frequencies from 30 MHz to 3 GHz, and a prototype chip is ready, with samples expected in 2007, Nufrontsoft said.
STiMi was developed by the Academy of Broadcast Science, part of a government ministry that regulates broadcasting in China. STiMi supports the S- and UHF/VHF bands and will use both satellites and terrestrial relays to implement coverage. Little more is known about the technology.
Chinese officials said they hope to finish trials with the new technologies by the end of 2006 and to move into commercial trials in 2007. Since the government has officially approved DMB-T/H, it could be tough for other domestic rivals to win out.
-- Cai Yan contributed to this story.
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