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Chapter 14
Video and Multimedia Networking

I have never received a telephone call that justified the excitement and fuss of the electronics involved. If I can’t see somebody I love, for instance, such as a daughter, or a son, I would rather receive a letter.

—William Saroyan, “Let’s Just Nobody Ever Forget Joan Castle.”Sons Come & Go, Mothers Hang in Forever, 1979

One may wonder how critical video and multimedia networking are to our daily lives. The answer is not clear. While we all understand that a picture can be worth a thousand words, the ability to engage in interactive video or multimedia communications currently is not necessarily all that important to most of us, either personally or professionally. Video and multimedia networking currently is expensive in terms of both bandwidth and equipment, although these costs will certainly come down over time. Many of the highly touted benefits have yet to be proven, although a compelling case is developing.

Certainly, video and multimedia have application in education. People tend to have different learning styles. Some are visual learners, some are auditory and still others tend to be more kinesthetic. In any event, the addition of the visual information stream certainly assists in the educational process, as it does in the communications process. A fascinating application is in the world of healthcare. As I will discuss later in this chapter, telemedicine has proved itself to be of great importance in the delivery of high-quality medical care to remote areas where specialists, and even general practioners, may not be available.

Video Communications Defined and Evolved

“What’s past is prologue,” wrote William Shakespeare in The Tempest. So it is in video, as it is in all of life and all of technology—without history, there is no future. Video (from the Latin video, meaningI see) communications has its roots in broadcast TV, which is transmitted over the airwaves, and still is the primary source of television in many areas and in most countries. The first true television mechanism was developed in 1884 by Paul Nipkow, a German engineer. Using a scanning disk, lenses, mirrors, a selenium cell, and electrical conductors, he was able to transmit images in rapid succession to a lamp, which changed in brightness according to the strength of the currents received. Using this mechanical scanning technique, Nipkow demonstrated that portions of a full image viewed in rapid succession (15 images or more per second) created the illusion of viewing the full image [14-l]. It later was discovered that viewing 15 or more images per second created the illusion of full motion due to electrochemical processing delays in the human eye. While this mechanical scanning approach was abandoned in later years, the concept of persistence of vision remains valid. A second process, know as the phi phenomenon, was first explained by psychologist and film theorist Hugo Munsterberg in 1916. This process explains the fact that we hallucinate, or believe that we see, a continuous action, rather than a series of still images—the mind, in effect, fills in the blanks [14-2]. Modern television and video systems create the illusion of motion by refreshing screens in rapid succession, a dot at a time and a line at a time.

The development of modern television was largely due to the efforts of Herbert E. Ives, a scientist at Bell Telephone Laboratories. Son of Frederick Eugene Ives, who in 1878 developed the first practical process for making halftone printing plates, Ives was oriented toward the visual world. He and his associates in 1923 combined the photoelectric cell with the vacuum tube repeater to produce the first commercial system for the rapid transmission of pictures over telephone wires, for use by newspapers. Using a scanning beam developed by Frank Gray, another Bell Labs scientist, multiple realtime images of people were transmitted in rapid succession and television was born. The first public demonstration was held in April 1927; with color television was demonstrated in June 1929 [14-3]. That experimental transmission included the transmission of pictures of an American flag, a watermelon, and roses. The transmitting system had three sets of photoelectric cells, amplifiers and glow-tubes, with each filtering out one color—red, green, or blue (RGB). At the receiving end, mirrors superimposed the monochromatic images to create a single color image [14-1]. In the 1930s, the first commercial television stations began operation over the radio waves.

Coaxial cable entered the world of television in 1936, with the first experimental transmission taking place between New York and Philadelphia. Jointly conducted by AT&T and the Philadelphia Electric Storage Battery Company (Philco), the experiment proved highly successful in terms of transmission performance as multiple frequencies could be transmitted over the same shielded (noise-free) medium. In 1950, AT&T opened the first coaxial cable for coast-to-coast TV transmission [14-4]. Community Antenna TeleVision (CATV), generally based on coaxial cable, largely has supplanted broadcast TV in the U.S. Relatively recently CATV has spread to a number of other developed countries, including England and Australia.

At this point, only two key evolutionary concepts remain—those of the iconoscope and kinescope. Vladimir Zworykin, a Russian immigrant, built on his graduate work in Russia where had studied the nature of fluorescence under Boris Rosing. On January 1, 1939, Zworykin received patents for his iconoscope (transmitting) and kinescope (receiving) tubes. These patents formed the basis for modern cameras and cathode ray tubes used as display devices (TV sets and computer monitors) [14-1] and [14-5].

Video communications extends well beyond broadcast TV and CATV, into videoconferencing, multimedia communications, and, ultimately, interactive TV. In this chapter the nature of the equipment and networks which support video and multimedia collaborative communications will be explored, as will related standards and costs.


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