What are the DTV
formats?
Digital Television formats defined
HDTV,
the highest level of DTV, will deliver up to 1080 scan lines,
more than double the scan lines of today’s TV signals and six
times the resolution. HDTV will also make it possible for TV screens
to have a wide 16:9 aspect ratio, similar to movie theater screens
- about a third wider than the 4:3 aspect ratio of today’s TV
screen. Add Dolby Digital sound, and HDTV will deliver an entirely
new experience for enjoying movies, sports and other TV programs.
To be considered HDTV,
the signal must be 1080i (using interlaced scanning) or 720p (using
progressive scanning). 1080i signals offer 1920 x 1080 resolution
and 720p offers 1280 x 720 resolution. Either way, the signal
is transmitted over a single channel at 1 million pixels per 1/60th
of a second.
SDTV signals
(at 480p or 480i) offer less detail, but more channels can be
transmitted simultaneously using the same bandwidth as HDTV. 480p
provides 704 x 480 resolution and is transmitted at half a million
pixels per 1/60th of a second. 480i offers 640 x 480 resolution
and is transmitted at a quarter of a million pixels per 1/60th
of a second.
This DTV tip is reproduced from "The ABCs
of DTV" with the permission of Sharp Electronics. Copyright 1998
Sharp Electronics Corporation.
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