Television

  
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Media Television 
Online Companion to Canadian program exploring broadcast communications. 
Undercurrents 
Canadian TV program about Information Age issues. 
Vanderbilt TV News Archive 
Nightly abstracts of US Network Newscasts since 1968. 
Federal Communication Commission 
Website for US government agency protecting public interests in communications. 
CRTC 
Website for the Canadian Radio-television and Telecommunications Commission. 
Sounds of Broadcasting History 
Hear history happening. From Texas Wesleyan University.

Television transmissions start with a television camera. Similar to a motion picture camera used for movies, the TV camera takes a large number of still pictures every second, so when played back in sequence the viewer receives the impression that it is a single image in motion. In North America the TV camera takes 30 pictures per second. But that is where the similarities end. Instead of recording the images onto film, the TV camera converts the image, along with the audio, into electronic signals. Every picture is broken down into hundreds of horizontal images, then each line is broken down even more into tiny picture elements called pixels. Each pixel is converted into an electric single that includes information the TV receiver will use to determine its specific colour and luminance (brightness). One pixel looks like a tiny dot of one colour, but when included with all the other pixels (over 200 000) of the screen, a comprehensible picture appears. 

Camera 
There are several types of video cameras used to record TV broadcasts, each having certain advantages depending on its application. In general they all do the same thing: the camera converts light waves into electrical signals that can reproduce moving pictures. This is accompanied by a microphone that converts sound waves into electrical signals that reproduce an audio track. The lens of a camera focuses the light of the image it is pointed at onto a target plate of a camera tube. This target plate consists of light-sensitive dots. These dots are scanned by an electron gun, that interprets the brightness of each dot. Because the camera tube can only interpret luminance, colour TV cameras use separate camera tubes for each primary colour (red, green, and blue). Filtering mirrors behind the lens split the light into the appropriate tubes. Once the light is converted into electric signals, an encoder combines them to form one stream of data, and bundles it with the audio track. The signal is then streamed through the transmitter, allowing your TV to receive the signal. 

Transmission 
Television transmissions can be received through several sources. Excluding those living in remote rural areas, most North Americans can receive TV through cable lines. When a consumer subscribes to cable, he or she pays a monthly fee to receive television signals through a coaxial cable. While the subscription is comparable to basic telephone service, viewers will receive high quality, reliable signals for major national television networks as well as popular specialty channels offering news, sports, children’s and educational programming, movies, music, and even shopping. People who can’t afford, or can’t access, cable television will usually use wireless broadcast television. By attaching an antenna to their home, viewers will receive most national television networks, but severe weather can interrupt access. For the ultimate in television viewing, consumers can pay a premium for digitally-transmitted satellite television. Anyone can access this service if they own a satellite receiver dish. Channels may be "scrambled", requiring you to subscribe to the channel to "decode" the picture. Satellite TV offers high quality signals and CD-quality audio, as well as access to channels that cable companies don’t offer, such as networks transmitting from other countries. 

Receiver 
When the signal reaches your television, electronic circuits separate the audio signal, and send it to an amplifier, then out a speaker. The video signal runs through a decoder, where each colour is separated once again. Electron guns, one for each colour, shoot electron beams when necessary at the screen, which is coated with phosphor dots. Every pixel of the screen has a dot for each colour. A shadow mask sits behind the screen to ensure the electron dots only hit phosphor dots of their own colour. When the electrons hit the dots, they glow. The television signal transmits the visual portion of the TV transmission sequentially, one line of pixels at a time, but so rapidly your television screen appears to be lit up continuously. 

When televisions originally became popular, they only offered monochrome (black and white) images. When colour TV was purposed, the United State’s communication regulator FCC ruled that if a colour system was adopted, it would have to be compatible with the existing monochrome  TV’s, which were so widely used. 

History 
The history of TV begins when German Paul Gottlieb Nipkow patented the Nipkow Disc in 1884. This flat circular disc was perforated with tiny holes that spiralled from the centre to the rim. The disc revolved in front of your eye as the image was scanned all over the disc. Later, Scotsman John Logie Baird added a photoelectric cell into the system. The cell could translate light into an electric signal, which could play back the image. Despite the advances, the disc still didn’t succeed. 

In 1923 Vladimir Kosma Zworykin invented the iconoscpe. Shortly after that American Philio Taylor Farnsworth created the image dissector tube. As further development in radio broadcasting and electronics occurred, efficient television sets were available following World War I. Public television broadcasts began in England in 1927, with the United States following in 1930, but regular programming didn’t begin in England until 1939, and on April 30, 1939, alongside the opening of New York’s World’s Fair, regular broadcasting also began in the United States. After World War II, 12 commercial stations were in operation. Exponential growth occurred in the following years, and by the late 1980’s, 98% of American homes had a television, and over 1300 television stations were available. 

In 1969, 200 000 people experienced Neil Armstrong’s moon walk, and in 1994, an estimated 2 billion viewers watched the final game of Soccer’s World Cup ‘94. These life-touching experiences prove just how monumental this communication technology is, and serve as evidence that television will live on as an incredible icon of 20th century society.