high-definition television

Type of digital television system offering a significantly greater number of scanning lines, and therefore a clearer picture, than that provided by conventional systems. Typically, HDTV has about twice the horizontal and vertical resolution of current 525-line (such as the American standard, NTSC) or 625-line standards (such as the British standard, PAL); a frame rate of at least 24 Hz; and a picture aspect ratio of 9:16 instead of the current 3:4. HDTV systems are rapidly being introduced in many countries.

In May 2003 the US Federal Communications Commission (FCC) regulated that all commercial and non-commercial TV stations in the USA must begin digital broadcasts for at least part of their operational schedule. The FCC set a target that all TV stations must simulcast all of their NTSC programming on a digital channel by April 2005. Federal law now requires that all analog TV broadcasts in the USA should end by February 2009.