E-VSB Proponents Encourage 'Robust' Option as ATSC Prepares to Ratify Proposed Standard

by Gary Arlen Advanced Television Systems Committee (ATSC) members are voting this month on a proposal to include an Enhanced-VSB (Vestigial Side Band) modulation mode in the ATSC digital television (DTV) standard. The proposed revision would update the core digital television standard, creating a new optional operati
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by Gary Arlen

Advanced Television Systems Committee (ATSC) members are voting this month on a proposal to include an Enhanced-VSB (Vestigial Side Band) modulation mode in the ATSC digital television (DTV) standard. The proposed revision would update the core digital television standard, creating a new optional operating mode for broadcasters and reception capability for DTV receivers.

The E-VSB ballot is being sent to 140 member companies in June, with voting scheduled to continue for four weeks. According to ATSC bylaws, the E-VSB standard will be adopted if two-thirds of participating voters approve the new more-robust mode, which will complement the 8VSB technology that has been part of the ATSC format since its creation.

During an electronic roundtable held before balloting began, executives from three organizations that support the proposed E-VSB standard exchanged views on the outlook for E-VSB. Participating in the exchange were Lynn Claudy, NAB's senior VP, Technology; Mike DeClue, senior VP-technology and engineering, Clear Channel Broadcasting and Richard Lewis, senior VP-research and technology, Zenith Electronics.

TV TECHNOLOGY: Why is this E-VSB debate resurfacing at this time, and how are the sides lining up?

DeCLUE: Generally speaking, the sides divide between the consumer electronics makers and the broadcasting folks.

LEWIS: It's part of the ongoing struggle for broadcasters to remain competitive in a rapidly changing marketplace. Rather then aligning along industry lines, we see more of a grouping of visionaries and those that don't care about free over-the-air broadcasting. These visionaries are pushing for new tools that will allow both broadcasters and manufacturers to deliver compelling products to customers in the future.

CLAUDY: Adding the optional E-VSB mode to the ATSC DTV standard really shouldn't cause any debate. It's a win-win-win proposition for broadcasters, receiver manufacturers and--especially--consumers. E-VSB transmission fosters deployment of new portable receiving devices and innovative new digital services for those devices. That strengthens the digital over-the-air broadcast service and that's good for the DTV transition.

TV TECHNOLOGY: What are the most important functions of E-VSB?

CLAUDY: Flexibility. Broadcasters [can] offer a diverse range of over-the-air services reliably to consumers. That will be a key accelerant for the DTV transition. E-VSB offers a number of potential reception improvements. Reducing the threshold carrier-to-noise ratio for successful reception of E-VSB by 6 dB compared to 8VSB is perhaps intuitively the most dramatic.

DeCLUE: The most important and still somewhat controversial aspect is the improved reception in multipath conditions. We are an over-the-air service, with the necessity to reconnect with our customers. Anything that aids that reconnection is very important.

TV TECHNOLOGY: Let's look at the "robust" aspect of E-VSB standard. Why is it important to the DTV transition?

DeCLUE: It helps us further penetrate into the home in an "over the air" fashion. It is incredibly important, philosophically as well as practically, in our battle with cable, telcos and satellite.

CLAUDY: With E-VSB, the broadcast signal is divided into two parts: the "normal" stream and the "robust" stream. The data rate apportioned to each stream is under the control of the broadcaster. Existing receivers will receive the "normal" stream and ignore the "robust" stream. New receivers will be necessary to receive the "robust" stream but the nature of the "robust" encoding is such that successful reception can be achieved under conditions that are not possible with 8VSB transmissions.

LEWIS: E-VSB provides a signal with a lower signal-to-noise requirement ... the receiver is four times more sensitive than a standard receiver. This is the kind of flexible platform that the industry needs to launch exciting new services reaching handheld and mobile devices. These new devices will accelerate the transition just as DVD players have revived the video market.

TV TECHNOLOGY: Can broadcasters carry HDTV if they use E-VSB?

DeCLUE: Certainly we will continue to carry HDTV in our main channel. It is not even a challenge, technically or operationally, to carry both services simultaneously. The higher quality of terrestrial broadcast HD (and SD as well) sets us apart from cable or satellite.

CLAUDY: HDTV is the flagship service for digital terrestrial broadcasting and broadcasters are not going to abandon it. HDTV is currently most prevalent during prime time and [special events]. There are many hours during the day when many broadcasters' data-carrying capacity is underutilized, leaving capacity available for E-VSB applications. Even when HDTV is being carried, many broadcasters have chosen to apportion some of their data capacity for other services, having [determined] that the impact on the quality of the HDTV program ... will be acceptably small.

TV TECHNOLOGY: Will the adoption of E-VSB slow down implementation of the FCC's DTV tuner mandate?

CLAUDY: E-VSB will have no effect at all. E-VSB capability is an option for broadcasters and an option for receiver manufacturers. It's not part of the DTV tuner mandate any more than the ability to receive and process data broadcasts is required. E-VSB applications and devices will develop according to marketplace forces, not government mandates.

TV TECHNOLOGY: What new DTV business models are broadcasters putting into place that will be affected by adoption of E-VSB?

DeCLUE: Clear Channel is a part of the Emmis "Digital Antenna Service" project. The DAS, if successful, will consume more of the available bandwidth of a station than the E-VSB system. In fact, direct payout of the DAS system may discourage broadcasters from immediately implementing services in the E-VSB. On the other hand, once E-VSB-enabled devices become available, more pressure will mount to service those devices.

CLAUDY: A consistent new media trend is that consumers want to access media content wherever they are on a media device of their choosing. E-VSB capability will let broadcasters begin to play in the new consumer-demand-driven space.

TV TECHNOLOGY: There's some concern about additional patent license fees for use of E-VSB. Will such fees affect broadcasters or CE manufacturers?

DeCLUE: These costs should be [included] in the price of the device enabled, and paid by the user of the device on a one-time basis.

LEWIS: Zenith has worked hard to ensure that E-VSB would not be a royalty burden on manufacturers. We have included the E-VSB essential patents in our standard 8VSB-licensing program at no extra charge for the life of the 8VSB patents. The actual manufacturing cost should be minimal and will benefit greatly from the upcoming tuner mandate.

TV TECHNOLOGY: How do you respond to the concerns that E-VSB adoption will make obsolete the DTV sets already bought by early adopters?

CLAUDY: That's either a misunderstanding or misplaced paranoia. Broadcasters will continue to serve all the existing legacy sets--they're required to by FCC regulations and they're also required to serve existing sets by business imperatives. To do otherwise wouldn't make business sense even if it were legal.

DeCLUE: We remain committed to delivering our main channel to all sets. For the foreseeable future, our revenue is tied to that main channel. We are in a race to keep and expand our viewer universe. We are not going to jeopardize that race by alienating a portion of our viewers.

LEWIS: From the outset, E-VSB was designed for backward-compatibility. We are talking about adding incremental functionality. High definition will remain the centerpiece of the digital transition and all parties have agreed to limit the use of E-VSB to ensure that current DTV sets are not made obsolete. Just as with audio upgrades such as moving from Dolby Pro Logic to Dolby Digital, older units will benefit from new features while older sets maintain their functionality.

TV TECHNOLOGY: What's your outlook for the DTV transition and the services that E-VSB will enable?

DeCLUE: The DTV transition is mandated by regulation, period. The longer it takes for over-the-air broadcast television to find new viable businesses made possible by DTV, the greater the reluctance to fully embrace the transition.

LEWIS: If E-VSB is not adopted we will have missed a great opportunity. A market need exists for this technology and this need will be met. Without a standard, broadcasters would adopt this new technology in proprietary systems, [which would create] incompatibilities and higher cost for consumers. Lacking the certainty that a standard provides, this would also limit the ability of manufacturers to participate in supplying this equipment.

CLAUDY: U.S. broadcasters want to participate in the global trend toward portable and mobile media, and such capabilities are already being considered around the world. E-VSB will be a first important step in that direction for the ATSC DTV Standard.


The current ATSC membership vote on the E-VSB standards proposals marks the culmination of a four-year standards-setting process. During this period, the optional set of enhancements was tested and evaluated in both laboratory and real-world situations. Reports on the outcome of this ATSC vote will appear in future issues of TV Technology and at www.tvtechnology.com.