2/2/06

The Telecommunications Act of 1996

This act was passed by congress and signed by the president. One of its provisions requires all terrestrial TV stations in the country to convert to digital modulation. (Contrary to a persistent rumor, the VHF channels will not be abandoned.)

The deadline for this switch is February 17, 2009. To stay competitive, all cable systems are rapidly converting to digital, but there is no deadline for that.

The pre-existing TV technology is called analog. It is also called NTSC (National Television System Committee), which are the people who defined it. The NTSC spec was created in 1946, updated for color in 1953, and updated for stereo in 1984. Both of these updates were backward compatible, rendering nobody’s TV set obsolete. But the new digital standard is totally different. The only thing it has in common with NTSC is the 6 mega-hertz channel width. To continue using an NTSC TV after 2009 you might have to buy a converter box, which will probably cost about $60. These boxes are not yet available. You will not need such a box if you can rely on a cable or satellite box that has an NTSC output.

The new digital standard is called ATSC (Advanced Television Standards Committee). The government will require that all new TVs be able to receive ATSC channels. The ATSC standard includes multiple formats from 640x480 pixels to 1920x1080 pixels. All TVs must receive all of these digital formats and display them suitably. The broadcaster chooses the format.

To make the transition gradual, the FCC is temporarily giving all terrestrial TV stations a second channel, so that they can broadcast a digital channel along with their analog channel until 2009. There are 1700 terrestrial TV stations in the U.S. 1550 of them have their digital channel on the air. Most affiliates of the seven major networks (about 850) transmit some high definition programs. Over 95% of the U.S. population can receive some high-def programming from these stations. (These numbers are as of December 2005.)

The bad news:

• The cost to consumers of the new hardware.
• Home TV systems may be especially complicated during the transition.
• The picture-in-picture feature many people enjoy will largely disappear as TV set designers concentrate on more important things, but it will eventually make a comeback.
• NTSC images sometimes look worse on a big high-def set than on a small standard TV.

The good news:

• The quality of TV reception will improve dramatically. Temporary inconvenience, permanent improvement.

This page is part of “An HDTV Primer”, which starts at www.hdtvprimer.com