It's "all systems go" for America's new mobile digital television (DTV) broadcasting service that is expected to roll out to hundreds of broadcast TV stations this year, following years of development and engineering to assure that the new standard operates as advertised and fits "hand in glove" with existing HDTV broadcasts.
At a technology conference hosted here today by the Advanced Television Systems Committee Inc. (ATSC), LG Electronics' Wayne Bretl highlighted the technology behind mobile DTV for the scores of engineers, manufacturers and broadcast TV executives in attendance to learn more about how mobile DTV operates in a real world environment.
Bretl, principal engineer for LG's Zenith R&D subsidiary, was one of four speakers describing the various aspects of the mobile DTV standard that was adopted by the ATSC in October 2009. Other speakers described technical strategies for local broadcast station implementation of the standard and coordination efforts within the electronics industry.
In his remarks about the "Physical Layer" of the A/153 ATSC Mobile DTV standard, which is compatible with high-definition digital TV broadcasts that have been transmitted by local TV broadcasters for over a decade, Bretl highlighted that mobile DTV was designed to be easily received while inside moving vehicles - an engineering feat not addressed in the original digital TV standard.
"Our challenge in developing the mobile DTV physical layer was to ensure that the current method of transmitting over-the-air HDTV was not negatively affected by the addition of mobile programming," Bretl said. "Layered on top of the regular ATSC transmission are entirely new packets of information that augment the signal with additional training sequences, forward error correction, and encoded transmitter and channel data that insures that the receiver will be in sync with the transmitter."
"For the viewer, that means a solid signal even in a very challenging environment like a fast-moving train or while watching from the backseat of a car," said Bretl, whose technical presentation explained pre-processor and post-processor hardware modules as well as the ATSC Transport Packets in the studio-transmitter link containing mobile DTV data.
Legacy ATSC receivers, from today's flat-panel HDTVs to those first digital TV receivers shipped 12 years ago, essentially ignore the additional mobile DTV information, Bretl explained. In turn, new mobile DTV receivers are designed to specifically look for the new data, receive it, decode it, and display it - typically on a handheld device like a new portable DVD player or a prototype cell phone equipped with mobile DTV circuitry.
In fact, the first consumer product certified to comply with the new ATSC Mobile DTV Standard is LG's DPH570MH, a unique battery-powered DVD player with a seven-inch screen and an antenna for easy pickup of mobile DTV programs such as those that are being sent now in the Washington, D.C. market.
Mobile DTV Products Coming in 2010
Ideal for reception of mobile DTV any time, virtually anywhere, and at any speed, the DP570MH Mobile Digital Television offers the flexibility of both over-the-air reception and the convenience of built-in DVD playback. Equipped with stereo speakers and a 7-inch wide screen to display crystal clear digital TV images, the LG Mobile Digital TV is designed so that its display screen can be tilted to the viewer's preferred viewing angle. When not in use, the clamshell-style screen folds down and the device shrinks to about 9.5 inches by 6.5 inches - or about the size of a small hardback book.
The DP570MH comes equipped to play DVD movie discs and audio CDs, and it can also display .JPG photos and play WMA music files from its USB2.0 connection. The Mobile Digital Television comes equipped with two earphone jacks so that more than one passenger can enjoy mobile DTV shows or movies in the back seat of the car, or on a train. A removable battery powers the device for up to 2.5 hours in TV mode or up to 4.5 hours during DVD playback. Both AC and Auto power adaptors are included. The DP570MH Portable Television with integrated DVD player will be available later this year at a suggested retail price of $249.
New Chips in the Pipeline
Co-developer of the technology at the heart of the ATSC Mobile DTV standard, LG Electronics began mass production of the critical component for mobile DTV reception - the LG2160A integrated circuit (IC) chip - last June. The latest version, the LG2160R single chip design that includes both the tuner and demodulator, was announced in January.
Bretl said that next month LG plans to release its next-generation mobile DTV chip, the LG2161R receiver IC, which is even smaller, consumes less power, supports various interfaces and provides improved performance.
LG mobile DTV chips already can be found in a variety of new products being introduced by various manufacturers, from laptop USB accessory receivers to netbooks with integrated mobile DTV tuners and a range of prototype devices.
Proven Standard Delivers Robust Signals
Standardized by the ATSC and formally adopted as a standard in October 2009, the new ATSC Mobile DTV Standard allows broadcasters to use a portion of the existing 19.4 Megabit-per-second DTV channel capacity to transmit data with extremely robust characteristics suitable for mobile, pedestrian and handheld applications. The mobile DTV signal is also compatible with 8-VSB DTV, which was also developed by Zenith, LG's U.S. research and development lab.
Bretl says engineers working on the project rose to the challenge of developing a system that could respond to rapidly changing signal ghosting and also improve resistance to signal fading in a mobile environment.
"We've proven that a relatively simple upgrade to the original ATSC standard prepares broadcasters for what consumers want - the ability to see their favorite local channels virtually anywhere they go," Bretl said.
"The current rollout of mobile DTV follows rigorous field testing in Chicago, Columbus, Las Vegas, San Francisco, Raleigh, Dallas, Baltimore, Denver, Milwaukee, Atlanta, Seattle, and Washington, D.C. as well as Buenos Aires and Santiago. We're ready for full scale implementation of mobile DTV technology."