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This page is a list of the experimental television stations before 1946. After 1945 (in the United States) the television frequencies were opened up to commercialization and regular broadcasts began. Regular broadcast television start dates vary widely by country; in many regions, initial broadcast video deployment was delayed due to ...
- History of television
Radio giant RCA began daily experimental television...
- Television
In 1928, Baird's company (Baird Television Development...
- Experimental Television Center
Experimental Television Center. Coordinates: 42.102103°N...
- Experimental television
This page was last edited on 19 June 2013, at 14:41 (UTC).;...
- History of television
- History
- Technical Aspects
- Recording
- Bibliography
- See Also
- External Links
Early research
The first mechanical raster scanning techniques were developed in the 19th century for facsimile, the transmission of still images by wire. Alexander Bain introduced the facsimile machine in 1843 to 1846. Frederick Bakewell demonstrated a working laboratory version in 1851. The first practical facsimile system, working on telegraph lines, was developed and put into service by Giovanni Casellifrom 1856 onward. Willoughby Smith discovered the photoconductivity of the element selenium in 1873, l...
Television demonstrations
As a 23-year-old German university student, Paul Julius Gottlieb Nipkow proposed and patented the Nipkow disk in 1884. This was a spinning disk with a spiral pattern of holes in it, so each hole scanned a line of the image. Although he never built a working model of the system, Nipkow's spinning-disk "image rasterizer" was the key mechanism used in most mechanical scan systems, in both the transmitter and receiver. Constantin Perskyi had coined the word television in a paper read to the Inter...
Color television
John Baird's 1928 color television experiments had inspired Goldmark's more advanced field-sequential color system. The CBS color television system invented by Peter Goldmark used such technology in 1940.In Goldmark's system, stations transmit color saturation values electronically; however, mechanical methods are also used. At the transmitting camera, a mechanical disc filters hues (colors) from reflected studio lighting. At the receiver, a synchronized disc paints the same hues over the CRT...
Flying spot scanners
The most common method for creating the video signal was the "flying spot scanner", developed as a remedy for the low sensitivity that photoelectric cells had at the time. Instead of a television camera that took pictures, a flying spot scanner projected a bright spot of light that scanned rapidly across the subject scene in a raster pattern, in a darkened studio. The light reflected from the subject was picked up by banks of photoelectric cellsand amplified to become the video signal. In the...
Larger videos
A few mechanical TV systems could produce images several feet or meters wide and of comparable quality to the cathode ray tube (CRT) televisions that were to follow. CRT technology at that time was limited to small, low-brightness screens. One such system was developed by Ulises Armand Sanabriain Chicago. By 1934, Sanabria demonstrated a projection system which had a 30-foot (9.1 m) image. Perhaps the best[according to whom?] mechanical televisions of the 1930s used the Scophonysystem, which...
Aspect ratios
Some mechanical equipment scanned lines vertically rather than horizontally, as in modern TVs. An example of this method is the Baird 30-line system. Baird's British system created a picture in the shape of a very narrow, vertical rectangle. This shape created a "portrait" image, instead of the "landscape" orientation – these terms coming from the concepts of portrait and landscape in art– that is common today. The position of a framing mask before the Nipkow disk determines the scan line ori...
In the days of commercial mechanical television transmissions, a system of recording images (but not sound) was developed, using a modified gramophone recorder. Marketed as "Phonovision", this system, which was never fully perfected, proved to be complicated to use as well as quite expensive, yet managed to preserve a number of early broadcast imag...
Beyer, Rick, The Greatest Stories Never Told : 100 tales from history to astonish, bewilder, & stupefy, A&E Television Networks, 2003, ISBN 0-06-001401-6Cavendish, Marshall (Corp), Inventors and Inventions, Marshall Cavendish, 2007, ISBN 0-7614-7763-2Huurdeman, Anton A., The worldwide history of telecommunications, Wiley-IEEE, 2003, ISBN 0-471-20505-2Sarkar, Tapan K. et al., History of wireless, John Wiley and Sons, 2006, ISBN 0-471-71814-9This category is for all experimental television stations from 1927 to 1946. Most of the stations are located in the United States, however some are located in England, Germany, and Canada. Up to 1936, television was primarily broadcast via mechanical television technology.
