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The expansion of hdtv is High-definition television. The hdtv means
television signals broadcast with a higher resolution than traditional formats
like NTSC, SÉCAM, PAL. The hdtv is broadcasted digitally, except for early
analogue formats in Europe and Japan.
Historically, the term high-definition television was also used to refer to
television standards developed in the 1930s to replace the early experimental
systems, although, not so long afterwards, Philo T. Farnsworth, John Logie Baird
and Vladimir Zworkin had each developed competing TV systems but resolution was
not the issue that separated their substantially different technologies. It was
patent interference lawsuits and deployment issues given the tumultuous
financial climate of the late 20's and 30's. Most patents were expiring by the
end of WW2 leaving the market wide open and no worldwide standard for television
agreed upon. The world used analog PAL, NTSC, SECAM and other standards for over
half a century.
The terms HD ready and HD compatible are being used around the industrial world
for marketing purposes. They indicate that a TV or display is able to accept
video over an HDMI connection, using a new connector design, the main purpose of
which seems to be to ensure that digital video is only passed over an interface
which, by agreement, incorporates copyright protection. Even HD-ready sets do
not necessarily have enough pixels to display video to the 1080-line (1920x1080)
or 720-line (1280x720) HD standards in full resolution without interpolation,
and HD-compatible sets are often just standard-definition sets with an HDMI
input. This is a confusing use of the terms HD and hdtv.
MPEG-2 is most commonly used as the compression codec for digital hdtv
broadcasts. The hdtv is capable of "theater quality" audio because it uses the
Dolby Digital (AC-3) format to support "5.1" surround sound.
Japan has the earliest working hdtv system still in use, with design efforts
going back to 1979. Japan began broadcasting analog hdtv signals in the early
1990s using an interlaced resolution of 1035 lines (1035i). The Japanese MUSE
(Multiple sub-nyquist sampling Encoding) system, developed by NHK Science and
Technical Research Laboratories (STRL) in the 1980s, employed filtering tricks
to reduce the original source signal to decrease bandwidth utilization.
Japan is forerunner of hdtv in the world. Japan terrestrial broadcast of HD via
ISDB-T started in December 2003.
The hdtv transmission in Europe started in 2004. Euro1080 is the pioneer in hdtv
transmission in Europe. Australia started HD broadcasting in January 2001.
CHUM Limited's Citytv in Toronto was the first hdtv broadcaster in Canada and
CBC (Canadian Broadcasting Corporation) officially launched hdtv programming on
March 5, 2005.
Mexican television company Televisa experimented hdtv broadcasts in the early
1990s, in collaboration with Japan's NHK.
The hdtv specifications are defined by the ATSC in the United States. An hdtv-compatible
TV usually uses a 16:9 aspect ratio display with an integrated ATSC tuner. Lower
resolution sources like regular DVDs may be upscaled to the native resolution of
the TV.
The hdtv services were made available in the Republic of Korea in 2005 and
Brazil is expected to go for it in 2006.
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