Migration to Digital Television —  Background information

What is Digital TV?

Digital Television is a new broadcasting technology that allows signals to be delivered virtually free of interference. By transmitting the information used to make a TV picture and sound as “data bits” (as a computer does) will allow for transmission of pictures with a higher resolution and dramatically better picture and sound quality than is currently available.

Why are we switching to Digital TV?

Digital Television (DTV) is more efficient than the current analog system. In the same bandwidth a broadcaster can provide one analog channel of programming, a broadcaster can provide a super sharp “high definition” (HDTV) program or multiple “standard definition” (SDTV) programs simultaneously. Providing multiple program streams is called “multicasting.” The number of programs a broadcaster can send depends on the level of picture detail, or resolution.

Going digital has additional benefits including:

• Increased channel capacity such that more channels can be offered within a fixed amount of broadcast bandwidth.
• Increased programming options including interactivity and Video-on-Demand (VoD).
• Improved picture quality even with a standard-definition signal.
• Improved security to prevent unauthorized persons from receiving services.

What is HDTV?

HDTV is a DTV service that provides high resolution programming in a wide screen format. The current analog TV picture is made up of 480 horizontal lines. HDTV can have up to 1080 lines, allowing for incredible picture detail.

What is required to watch an HDTV program?

An HDTV decoder (set-top) or television with an integrated HDTV tuner is required in order watch broadcasts in HDTV format.

What is the FCC Transition Plan?

As of May 2003, more than 1,000 stations were on the air with DTV signals, and every major TV market was served by at least one DTV station. The Target date set by Congress for the completion of the transition to DTV is December 31, 2006. That date however, may be extended until 85% of homes in an area are able to watch the DTV programming. At that point, broadcasting on the analog channels will end and that spectrum will be put to other uses. Until the transition is completed, TV stations are required to broadcast both their digital and analog signals. By law, all signals will be in HD as of June 2009.

What is the basically technology that makes this possible?

Compression is a crucial step to making digital TV a practical and profitable service. Compression enables the shift to digital television by drastically reducing the amount of data bandwidth required to retransmit a digitized program. As a compression and transmission medium for digitized audio and video, today’s digital broadcast industry relies mainly on MPEG-4, the standard developed by the Motion Picture Experts Group.

MPEG-4 based protocols have become the standard for carrying broadcast-quality compressed digital video, audio and data over terrestrial, satellite and cable broadband networks. In short, MPEG-4 has become to digital what IP is to the Internet.

The MPEG standards define the syntax, or structure and semantics of a compressed bit stream and the procedure for decoding the stream back in the original video and audio content. Since neither specific algorithms nor encoding methods are defined by MPEG, these can improved over time without any risk of violating the standards. This flexibility affords manufacturers the opportunity to gain a proprietary advantage from new technical developments.