Dueling modulation schemes slow rollout of DTV
By Patrick Mannion
EE Times
(12/28/00, 12:45 p.m. EST)
eetimes.com
MANHASSET, N.Y. — With the curtain set to go up on the Consumer Electronics Show Jan. 6, the pace of the U.S. digital TV rollout remains excruciatingly slow. Receivers cost too much; programming is spotty; cable-TV incompatibility issues dog deployments. And a global duel between two modulation schemes continues to divide DTV backers.
Playing both sides of the modulation fence, one chip maker, NxtWave Communications Inc. (Langhorne, Pa.), announced silicon last week that comes in versions for both schemes.
NxtWave's agnosticism comes as debates persist in the United States over whether eight-level vestigial sideband (8-VSB) should be supplanted by coded orthogonal frequency-division multiplexing (COFDM) for broadcast DTV.
The latest 8-VSB evaluation report from the Communication Research Center (Ottawa), which found some problems with indoor reception, and the choice of COFDM by both Russia and Hong Kong have done little to help 8-VSB's case. The trump card could be China, which has yet to select a standard for a DTV market that could be worth $12.5 billion.
The broadcast standard debate is but one of a long list of issues dogging DTV. Cable networks continue to wrestle the FCC and the Consumer Electronics Association (CEA) over compatibility between cable systems and DTV sets. And all sides are coping with the paucity of programming as studios hold off on providing more content until copyright protection issues are settled.
On a more basic level, the relatively high cost of the sets and consumers' lack of awareness of digital TV's benefits have made for little market pull. That has fed the catch-22 of the networks' reluctance to invest in expensive equipment for a service that few customers appear to want.
The net effect has been lower-than-expected sales of high-definition DTV sets this year, although the numbers are still up markedly over last year. According to recent market research figures from NPD Intelect (Port Washington, N.Y.), the number of units sold this year tops 206,000; last year's unit sales came in at 77,000. The figures respectively correspond to 12.5 percent and 4 percent of total TV sales dollars.
But almost all of the HDTV sets sold were "HDTV ready," meaning a set-top box would be required to take advantage of the high-definition and data features.
"The figures come way under CEA expectations, though the CEA tends to be somewhat optimistic anyway," said Mark Seavy Sr., editor of the Television Digest (New York).
The CEA recently quoted unit sales to dealers at 368,947 — nearly seven times the number of displays sold during the same period in 1999. The total is expected to have reached 425,000 by the end of this year. "But NPD prefers to quote the number of units actually sold," said Tom Edwards, an analyst at that firm.
From sports to spots
Seavy thinks a shift in manufacturers' marketing strategies is partly to blame for DTV's problems. "Last year, Panasonic underwrote [ABC's HDTV] Monday Night Football. This year, however, [manufacturers are] being more careful in how they spend their money. They've changed to just underwriting spot events, like Mitsubishi [did with] the U.S. Open."
Indeed, the lack of HDTV-format sports coverage by the major networks was a major consumer negative in a recent report issued by the Consumer Electronics Association. "Sales could be much higher with greater availability of DTV broadcast programming," said Todd Thibodeaux, CEA vice president of market research.
"But programming is only half the equation," said NPD's Edwards. "The other half is the high cost of sets and [low] consumer awareness of the benefits of HDTV." Consumers are satisfied with their analog sets; unless the set manufacturers do a better job of promoting the benefits, the public "won't know how much better HDTV really is," Edwards said.
The CEA has also taken the cable industry to task. In a report to the FCC issued Dec. 1, the group asserted that "manufacturers are unable to build cable-compatible DTV receivers because of incomplete cable industry standards," including specs for the point-of-deployment (POD)-host interface. The CEA also criticized the cable industry's progress toward a commitment it made in February to provide program system information protocol (PSIP) data.
And the report voiced a widely held, though unpublished, industry opinion that the "cable industry may have powerful economic incentives to maintain exclusive control over the electronic program guide and other features that until now have been exclusive to the cable-supplied set-top box." The CEA urged the FCC to promote an inter-industry standards process and set firm deadlines for the completion of specifications necessary for interoperability.
The DTV issues indicate the shaky position of network broadcasters in a country where 65 percent of homes use cable TV. The relevance of broadcast television is increasingly being called into question as cable and satellite channels multiply.
"The network audience is not only fracturing; it's falling apart," CEA's Thibodeaux said. "Every night over 50 percent — and growing — of all TV-watching eyeballs are not on ABC, NBC, CBS or Fox. The networks no longer own the monopoly on 'must see' programming."
But that doesn't quell the broadcast debates, which revolve around whether to stick with the Advanced Television Standards Committee's (ATSC's) choice of 8-VSB modulation or cease 8-VSB development and line up with Europe behind COFDM.
Appeal to Congress
After the FCC refused to reopen the U.S. modulation spec, COFDM backers petitioned Congress in July to add the alternative modulation approach to the U.S. transmission standard. The gambit prompted ATSC and other technical groups here to begin field tests to determine the extent of the purported reception problems.
Gary Chapman, chief executive of LIN Television Corp. (Providence, R.I.) and board chairman of industry group Maximum Service TV, told Congress that it would test the viability of COFDM and that it expected to report its findings by the end of 2000. But that reportedly has been pushed to next year.
As the U.S. industry awaits the results of the field tests, Canadian engineers have released a draft study concluding that reliable indoor DTV reception with 8-VSB was achieved at only about half of the 43 sites visited for the tests. However, the study found substantially better indoor reception when a 10-meter outdoor antenna was used.
Bernard Caron, manager of television systems and transmission for the Communication Research Center Canada (Ottawa), said he expects only slight changes in the draft report before it is released. "We found a few problems with indoor reception," Caron said. The 8-VSB scheme "worked as expected, but the expectation is changing" as to what constitutes good indoor reception.
The center plans a second test phase that will examine indoor reception from repeater stations that will be turned on and off to determine whether reception is improved or degraded. The tests, which will use next-generation DTV receivers, will also be conducted in congested downtown areas, Caron said. Preliminary test results could be available by the spring.
What's Caron's stance on the VSB-vs.-COFDM debate? "Each has its advantages. No system is perfect."
That sentiment was echoed by Matt Miller, president and chief executive officer of NxtWave. "Both are perfectly good standards, with their respective issues, of course, but to halt 8-VSB development now would only be detrimental to the deployment of DTV," he said. "You can't just take one standard out and plug another in. It could take at least two years to make the transition. The goal right now should be to go with what we have and get the DTV market off the ground."
Nonetheless, the 8-VSB rollout was hampered this year by a handful of defections among international backers of the standard. In the latest setback, the Russian Ministry of Print, TV Broadcasting and Telecommunications last week said it would select the European Digital Video Broadcast-Terrestrial (DVB-T) transmission spec as Russia's digital television standard.
The rivalry between ATSC and the European standard could be settled over the next two years, during which China is expected to select a transmission standard for its mammoth potential market. Critics of the U.S. spec point to Hong Kong's recent selection of the European spec as a sign that Beijing will follow suit. But others caution against applying the Hong Kong test results to other regions.
NxtWave, for now, is content to play in the neutral zone. Its 8-VSB version, the NXT2002, features improved algorithms to handle echoes, an 8051 microcontroller to offload cycles from the host, the ability to close the RF and I/F automatic gain controllers separately, and power consumption of 700 mW. The chip comes in a 100-pin TQFP and is priced at $20 each per 10,000.
The DVB-T (COFDM) version, the NXT6000, supports all modes defined by the DVB-T standard, including the hierarchical COFDM modes defined by ETSI, and meets the NorDig requirements for DTV platforms in Nordic regions. It consumes 800 mW, comes in a 64-pin LQFP and is priced at $15 each per 10,000.
Both chips are slated to ship in volume in the first quarter. |
