Television
University of Pitesti
Dolnośląska Wyższa Szkoła Przedsiębiorczości i Techniki w
Polkowicach
Dobrica Adrian
Dr inż. ZDZISŁAW PÓLKOWSKI
Polkowice, 2015
TOPICS MENU
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Definition
History
Color Television
The Social Impact of Television
Old Tv
Nowadays TV
jiad.org
Definition
The system or process of producing on a distant screen a series o
ftransient visible images, usually with an accompanying sound sig
nal.Electrical signals, converted from optical images by a camera t
ube, aretransmitted by UHF or VHF radio waves or by cable and r
econvertedinto optical images by means of a television tube inside
a television set .
A Television, commonly referred to as TV or Tele is
a telecommunication medium used for transmitting sound with
moving images in monochrome (black-and-white), colour, or
in three dimensions. It can refer to a television set, a television
program, or the medium of television transmission. Television is
a mass medium, for entertainment, advertising and news.
http://en.wikipedia.org/wiki/Television
http://dictionary.reference.com/browse/television
History
• The word television was coined at the World Fair in 1900. The history
of the idea for television is actually older than the history of television
itself. George Carey, a Boston civil servant, was thinking about
television systems in 1876, and in 1877 he made drawings of a
"selenium camera" to allow people to "see by electricity." Others were
also bringing forth thoughts and experimenting with ideas that would
lead to the invention of the television. Some think that the original
reason for the television was to be used as what we know as a
videophone.
• Paul Nipkow proposed and patented the first electromechanical
television system in 1884, but he could not develop a system that
worked. In 1925, the first publicly demonstrated working system in
the history of television, created by John Logie Bard, displayed a
moving silhouette. In 1928, Baird broadcasted the first transatlantic
signal and the first regularly scheduled television service began, and
in
1931,
the
first
live
transmission
was
made.
http://www.historyinfo.org/history-of-television.php
• The first fully electronic set in the history of television was
created in 1927 by Philo Taylor Farnsworth, but it wasn’t until
1934 that he created one that worked well.
• The first color transmission was demonstrated by Baird in 1928,
and the first color transmission of the electronically scanned era
in 1940. Color television field tests began in 1941, but because
of World War II and other circumstances, the first color
broadcast to the public did not occur until 1951. It was in the
1966-1967 season that the networks began broadcasting in full
color for prime time television.
• The history of television continues to advance even today.
From it’s invention, it has gotten bigger and bigger, of better
quality, and more popular. Ninety-eight percent of homes in
America had at least one television by the late 1980’s.
http://www.historyinfo.org/history-of-television.php
Color Television
• One of the great electrical engineering triumphs was the
development of color television in such a way that it remained
compatible with black and white television.
• A major driving force behind the majority of current color TV
standards was to allow black-and-white TVs to continue to be
able to receive a valid TV signal after color service was in
place.
http://electronicaupit.com/forum/index.php?board=13.0
Trireceptor theory of vision
why we use RGB monitors
• If you ask someone why red, green and blue are used in
computer monitors -- the immediate answer is "Because these
are the primary colors".
• If you then ask, "But why are these the primary colors?" -- the
answer you get is that "If you mix light of these colors together
you can make any color".
http://electronicaupit.com/forum/index.php?board=13.0
http://electronicaupit.com/forum/index.php?board=13.0
Color information transmission in TV
• In the most basic form, color television could simply be
implemented by having cameras with three filters (red, green
and blue) and then transmitting the three color signals over
wires to a receiver with three electron guns and three drive
circuits.
• Unfortunately, this idealized view is not compatible with the
previously allocated 6 MHz bandwidth of a TV channel. It is
also not compatible with previously existing monochrome
receivers.
http://electronicaupit.com/forum/index.php?board=13.0
• Therefore, modern color TV is carefully structured to preserve
all the original monochrome information -- and just add on the
color information on top.
• To do this, one signal, called luminance (Y) has been chosen
to occupy the major portion (0-4 MHz) of the channel. Y
contains the brightness information and the detail. Y is the
monochrome TV signal.
• Consider the model of a scene being filmed with three cameras.
One camera has a red filter, one camera a green filter and one
camera a blue filter.
http://electronicaupit.com/forum/index.php?board=13.0
• Assume that the cameras all adjusted so that when pointed at
"white" they each give equal voltages. To create the Y signal,
the red, green and blue inputs to the Y signal must be balanced
to compensate for the color perception misbalance of the eye.
• The governing equation is:
• For example, in order to produce "White" light to the human
observer there needs to be 11 % blue, 30 % red and 59%
green (=100%).
http://electronicaupit.com/forum/index.php?board=13.0
Multiplexing of Luminance and Chrominance
• Position the bandlimited chrominance at the high end of the
luminance spectrum, where the luminance is weak, but still
sufficiently lower than the audio (at 4.5 MHz).
• The two chrominance components (I and Q) are multiplexed
onto the same sub- carrier using QAM.
• The resulting video signal including the baseband luminance
signal plus the chrominance components modulated to f c is
called composite video signal.
http://electronicaupit.com/forum/index.php?board=13.0
www.astrology.co.uk
The Social Impact of Television
Television is a "window on the world" for news and
information.
• We previously noted that many social problems are only acted
up after they are reported on television.
• Newspapers and the print media provide a degree of separation
from reality, but TV graphically brings happenings right into
living rooms, complete with color, sound, time sequences, and
even to some degree, the associated "feelings."
http://www.cybercollege.com/frtv/frtv034.htm
Television provides needed escape and relaxation
• To a great extent we've already discussed this inprevious
modules.
• Suffice it to say, television allows us to momentarily escape our
problems and experience the experiences of other people.
• We can become awestruck with the beauty of and grace of the
arts, or caught up in the frenzy and excitement of an athletic
event. We can even allow ourselves to be momentarily lost in a
beautiful fantasy world.
http://www.cybercollege.com/frtv/frtv034.htm
Television introduces new ideas and information
• Before the mass media, an important threat to health, a new
medicine, or improved ways of doing things could take months
or even years to become commonly known.
• Today, that time is typically cut down to a day -- or even a few
hours.
• Included in this category are new products and services that will
make our life easier or safer, new recipes, important safety
procedures, and even instructions on home improvement and
repair.
http://www.cybercollege.com/frtv/frtv034.htm