|PDH Online Course Description
Learning Units (Hours)
“Now, we add sight to sound”
When Sarnoff, president of RCA, formally introduced television to the world (from a podium in front of the RCA Exhibit Building at the 1939 New York World’s Fair), he heralded it as: “the birth of a new art and a new industry, which eventually will provide entertainment and information for millions.” He was right. There were many others who would be instrumental in the development of “Seeing-at-a-Distance” (a/k/a “Tele-Vision”), some of them you’ve probably heard of such as Philo T. Farnsworth and Vladimir Zworykin, but there were many others whose names have been lost to history (i.e. Charles Francis Jenkins and John Logie Baird). Although David Sarnoff’s contribution was not technical, it was critical in that it was his vision of television’s potential (and his willingness to sacrifice millions of RCA dollars in pursuit of that vision) that would, ultimately, make the modern television industry a practical reality.
In its formative years, television - a derivative of radio, was seeking a path-of-least-resistance to commercial acceptance. By the mid-1920s, it seemed “Mechanical Television,” whereby a motor-driven spinning scanning disk formed images, was the answer. But there were those who realized the limitations of mechanical television and, instead, pursued an electronic solution, building upon the work of those who came before them. This would lead to the development and acceptance, by 1932, of “Electronic Television” as “the way forward.” Delayed by WWII, after the war monochrome (black-and-white) television would develop both technically and commercially into the fledgling industry David Sarnoff had foreseen. By the mid-1950s, the focus was on Chroma (color) television and, by the mid-1960s, color television had come-of-age. In the ensuing years, the “Holy Grail” would be “Mural TV” (flat-screen). With major advances in electronic technology, that too was made manifest.
Truth be known, it’s an optical trick that made motion pictures, and later television, possible. By presenting a sequence of still images in quick succession (at least 16x-per-second), the viewer interprets them as a continuous moving image. This illusion of movement is referred to as “Persistence of Vision.” Television, therefore, in addition to projecting a series of pictures, must actually break-up each picture into thousands of parts and transmit the parts one after the other, all within the time it takes for an ordinary moving picture projector to project one picture – not an easy task. Mechanical television used one or more revolving disks to cause an image to fall upon a photo-electric cell in a succession of tiny fragments of light of varying intensity. Instantly (thanks to the “Photo-Electric Effect”), the photo-electric cell translated the fragments into a fluctuating electric current of corresponding intensity. This varying current then was amplified and transmitted. At the receiving end, the procedure was basically reversed. Although viable, in the end it would prove inferior to Electronic Television which lacks any moving parts and operates at the speed-of-light.
This course includes a multiple-choice quiz at the end, which is designed to enhance the understanding of the course materials.
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