Samsung Electronics Co., Ltd. announced at NAB 2006 (followed by a live demonstration with handheld devices at the International Consumer Electronics Show (ICES) in January 2007) a new innovative technology that enables portable and mobile TV digital broadcasting in North America at very low cost, using broadcasters' existing facilities and frequency spectrum. At NAB 2007, Samsung will not only demonstrate an A-VSB mode with twice the efficiency (using half the broadcasting bandwidth) compared to Samsung's previous demonstration in January, but will also demonstrate the power of A-VSB's Single Frequency Network (SFN) tool for the first time.
Advanced-VSB (A-VSB) is a proposed open standard that broadcasters can implement at low cost, providing an all-new distribution channel through which broadcasters can reach consumers with live TV on the go via portable media devices, whether traveling by car or bus or walking down the street.
For the duration of NAB, live A-VSB transmissions will be sent from local Sinclair Broadcast Group TV station KVMY Las Vegas to mobile receivers operating on a chartered bus in the Convention Center area, using the station's current transmitter and frequency. The same programming will also be re-transmitted at a second frequency on a separate low-power SFN. The SFN is being set up with the support of ION Media Networks (which previously has conducted limited testing of A-VSB in Tampa, Florida) and will be operated under an experimental license to ION from the Federal Communications Commission. The SFN will have three transmitter sites, two located on structures north and south of the Convention Center along the Las Vegas Strip and one inside the Convention Center at the ATSC Digital TV Hot Spot. The SFN demonstration will show how A-VSB makes it easy for broadcasters to maintain complete signal coverage and transmission, filling in gaps between buildings and behind mountains for maximum service quality.
Together, Samsung Electronics and Rohde & Schwarz have developed A-VSB as a dramatic enhancement to the Advanced Television Systems Committee (ATSC) digital TV transmission standard.
The technology is being standardized in ATSC, and an ATSC-supervised lab test was conducted in November 2006, with field tests to be mounted in the first half of 2007. A completed standard is targeted for 2007, with implementation by broadcasters and consumer electronics manufacturers beginning soon afterward, aiming toward widespread commercial services before the February 2009 transition to all-digital TV broadcasting in the United States.
To support the rapid development of new services and new businesses for broadcasters, Samsung intends to make A-VSB evaluation kits (including prototype transmission and reception equipment) available on a limited basis to broadcasters and other partner companies in the third quarter of 2007.
Broadcasters Excited About A-VSB-Enabled Mobile Services
"Delivering mobile TV to consumers is critical to broadcasters and advertisers alike," said Brandon Burgess, President and CEO of ION Media Networks." By building partnerships across the industry and with strong companies like Samsung that are using advanced technologies, we believe we can capitalize on this growing opportunity. We are pleased to be testing A-VSB with Samsung and Rohde & Schwarz and supporting their A-VSB technology demonstration at NAB 2007."
"Sinclair has been a vocal advocate for mobile and portable services for a very long time," said Del Parks, VP of Engineering and Operations, Sinclair Broadcast Group. "We are pleased to support this technology demonstration at NAB in order to showcase the mobile and portable capabilities of A-VSB to the industry using the ATSC standard. This technology will enhance the value of our digital television spectrum by allowing us to provide services to cell phones, laptops and vehicles using our over the air signal."
What is Advanced-VSB?
A-VSB technology builds on the current ATSC transmission standard to enhance the ability of receivers to display television broadcasts while in motion, both indoors and outdoors. It also allows broadcasters to include multiple "turbo-coded" streams within the current main stream, resulting in stronger, clearer signal transmission. In addition, A-VSB eases the synchronization of broadcast signal timing among different towers in a Single Frequency Network (SFN). SFNs can improve the quality of broadcast service by providing uniform signal strength throughout a service area, so that receivers can receive a stronger signal from a nearby transmitter and take advantage of the spatial separation of multiple transmitters to mitigate obstacles such as hills and buildings.
How does A-VSB work?
First, a broadcaster adds a specified Supplementary Reference Sequence (SRS) to the transmitted signal. A-VSB receivers use the SRS in order to remain locked on to the transmission-including both the main signal and extra turbo signal(s)--even when dynamic interference would normally disrupt a signal, such as when the signal is reflected by moving objects near the receiver. A-VSB also makes it possible for the receiver to stay locked on to the signal when the receiver itself is moving, such as when a viewer is traveling with a portable TV. Moreover, as Samsung will demonstrate again at NAB 2007, the combination of SRS and Turbo code makes reception possible at high mobile speeds, such as in a car or on a train, and in urban environments which have a large amount of interference reflected from buildings and objects. When implemented, this breakthrough will enable fully mobile TV services using the existing frequencies and facilities of broadcasters, with minor upgrades to their transmitting equipment.
For the first time at NAB 2007, Samsung will demonstrate a "half-rate Turbo" mobile reception mode using half the bandwidth of the previously demonstrated "quarter-rate Turbo" mode. Half-rate mode is targeted for highway speeds, rather than the faster bullet train speeds which quarter-rate mode enables.
Is A-VSB backward compatible?
Yes, broadcasters can implement A-VSB technology with no impact on legacy (non-A-VSB) digital TV receivers, which will ignore the added information in the signal while continuing to receive the main TV stream (e.g., High-Definition TV programming). In addition, as A-VSB technology helps broadcasters deploy SFNs to fill gaps in the coverage of their service area, owners of legacy receivers may find their reception quality is also improved.