16 May 2009

Compact disc

Compact disc The invention: A plastic disk on which digitized music or computer data is stored. The people behind the invention: Akio Morita (1921- ), a Japanese physicist and engineer who was a cofounder of Sony Wisse Dekker (1924- ), a Dutch businessman who led the Philips company W. R. Bennett (1904-1983), an American engineer who was a pioneer in digital communications and who played an important part in the Bell Laboratories research program Digital Recording The digital system of sound recording, like the analog methods that preceded it, was developed by the telephone companies to improve the quality and speed of telephone transmissions. The system of electrical recording introduced by Bell Laboratories in the 1920s was part of this effort. Even Edison’s famous invention of the phonograph in 1877 was originally conceived as an accompaniment to the telephone. Although developed within the framework of telephone communications, these innovations found wide applications in the entertainment industry. The basis of the digital recording system was a technique of sampling the electrical waveforms of sound called PCM, or pulse code modulation. PCM measures the characteristics of these waves and converts them into numbers. This technique was developed at Bell Laboratories in the 1930’s to transmit speech. At the end of World War II, engineers of the Bell System began to adaptPCMtechnology for ordinary telephone communications. The problem of turning sound waves into numbers was that of finding a method that could quickly and reliably manipulate millions of them. The answer to this problem was found in electronic computers, which used binary code to handle millions of computations in a few seconds. The rapid advance of computer technology and the semiconductor circuits that gave computers the power to handle complex calculations provided the means to bring digital sound technology into commercial use. In the 1960’s, digital transmission and switching systems were introduced to the telephone network. Pulse coded modulation of audio signals into digital code achieved standards of reproduction that exceeded even the best analog system, creating an enormous dynamic range of sounds with no distortion or background noise. The importance of digital recording went beyond the transmission of sound because it could be applied to all types of magnetic recording in which the source signal is transformed into an electric current. There were numerous commercial applications for such a system, and several companies began to explore the possibilities of digital recording in the 1970’s. Researchers at the Sony, Matsushita, and Mitsubishi electronics companies in Japan produced experimental digital recording systems. Each developed its own PCM processor, an integrated circuit that changes audio signals into digital code. It does not continuously transform sound but instead samples it by analyzing thousands of minute slices of it per second. Sony’s PCM-F1 was the first analog-to-digital conversion chip to be produced. This gave Sony a lead in the research into and development of digital recording. All three companies had strong interests in both audio and video electronics equipment and saw digital recording as a key technology because it could deal with both types of information simultaneously. They devised recorders for use in their manufacturing operations. After using PCM techniques to turn sound into digital code, they recorded this information onto tape, using not magnetic audio tape but the more advanced video tape, which could handle much more information. The experiments with digital recording occurred simultaneously with the accelerated development of video recording technology and owed much to the enhanced capabilities of video recorders. At this time, videocassette recorders were being developed in several corporate laboratories in Japan and Europe. The Sony Corporation was one of the companies developing video recorders at this time. Its U-matic machines were successfully used to record digitally. In 1972, the Nippon Columbia Company began to make its master recordings digitally on an Ampex video recording machine. Links Among New Technologies There were powerful links between the new sound recording systems and the emerging technologies of storing and retrieving video images. The television had proved to be the most widely used and profitable electronic product of the 1950’s, but with the market for color television saturated by the end of the 1960’s, manufacturers had to look for a replacement product.Amachine to save and replay television images was seen as the ideal companion to the family TV set. The great consumer electronics companies—General Electric and RCAin the United States, Philips and Telefunken in Europe, and Sony and Matsushita in Japan—began experimental programs to find a way to save video images. RCA’s experimental teams took the lead in developing an optical videodisc system, called Selectavision, that used an electronic stylus to read changes in capacitance on the disc. The greatest challenge to them came from the Philips company of Holland. Its optical videodisc used a laser beam to read information on a revolving disc, in which a layer of plastic contained coded information. With the aid of the engineering department of the Deutsche Grammophon record company, Philips had an experimental laser disc in hand by 1964. The Philips Laservision videodisc was not a commercial success, but it carried forward an important idea. The research and engineering work carried out in the laboratories at Eindhoven in Holland proved that the laser reader could do the job. More important, Philips engineers had found that this fragile device could be mass produced as a cheap and reliable component of a commercial product. The laser optical decoder was applied to reading the binary codes of digital sound. By the end of the 1970’s, Philips engineers had produced a working system. Ten years of experimental work on the Laservision system proved to be a valuable investment for the Philips corporation. Around 1979, it started to work on a digital audio disc (DAD) playback system. This involved more than the basic idea of converting the output of the PCM conversion chip onto a disc. The lines of pits on the compact disc carry a great amount of information: the left- and right-hand tracks of the stereo system are identified, and a sequence of pits also controls the motor speed and corrects any error in the laser reading of the binary codes. This research was carried out jointly with the Sony Corporation of Japan, which had produced a superior method of encoding digital sound with its PCM chips. The binary codes that carried the information were manipulated by Sony’s sixteen-bit microprocessor. Its PCM chip for analog-to-digital conversion was also employed. Together, Philips and Sony produced a commercial digital playback record that they named the compact disc. The name is significant, as it does more than indicate the size of the disc—it indicates family ties with the highly successful compact cassette. Philips and Sony had already worked to establish this standard in the magnetic tape format and aimed to make their compact disc the standard for digital sound reproduction.Philips and Sony began to demonstrate their compact digital disc (CD) system to representatives of the audio industry in 1981. They were not alone in digital recording. The Japanese Victor Company, a subsidiary of Matsushita, had developed a version of digital recording from its VHD video disc design. It was called audio high density disc (AHD). Instead of the small CD disc, the AHD system used a ten-inch vinyl disc. Each digital recording system used a different PCM chip with a different rate of sampling the audio signal.The recording and electronics industries’ decision to standardize on the Philips/ Sony CD system was therefore a major victory for these companies and an important event in the digital era of sound recording. Sony had found out the hard way that the technical performance of an innovation is irrelevant when compared with the politics of turning it into an industrywide standard. Although the pioneer in videocassette recorders, Sony had been beaten by its rival, Matsushita, in establishing the video recording standard. This mistake was not repeated in the digital standards negotiations, and many companies were persuaded to license the new technology. In 1982, the technology was announced to the public. The following year, the compact disc was on the market. The Apex of Sound Technology The compact disc represented the apex of recorded sound technology. Simply put, here at last was a system of recording in which there was no extraneous noise—no surface noise of scratches and pops, no tape hiss, no background hum—and no damage was done to the recording as it was played. In principle, a digital recording will last forever, and each play will sound as pure as the first. The compact disc could also play much longer than the vinyl record or long-playing cassette tape. Despite these obvious technical advantages, the commercial success of digital recording was not ensured. There had been several other advanced systems that had not fared well in the marketplace, and the conspicuous failure of quadrophonic sound in the 1970’s had not been forgotten within the industry of recorded sound. Historically, there were two key factors in the rapid acceptance of a new system of sound recording and reproduction: a library of prerecorded music to tempt the listener into adopting the system and a continual decrease in the price of the playing units to bring them within the budgets of more buyers. By 1984, there were about a thousand titles available on compact disc in the United States; that number had doubled by 1985. Although many of these selections were classical music—it was naturally assumed that audiophiles would be the first to buy digital equipment—popular music was well represented. The firstCDavailable for purchase was an album by popular entertainer Billy Joel. The first CD-playing units cost more than $1,000, but Akio Morita of Sony was determined that the company should reduce the price of players even if it meant selling them below cost. Sony’s audio engineering department improved the performance of the players while reducing size and cost. By 1984, Sony had a small CD unit on the market for $300. Several of Sony’s competitors, including Matsushita, had followed its lead into digital reproduction. There were several compact disc players available in 1985 that cost less than $500. Sony quickly applied digital technology to the popular personal stereo and to automobile sound systems. Sales of CD units increased roughly tenfold from 1983 to 1985. Impact on Vinyl Recording When the compact disc was announced in 1982, the vinyl record was the leading form of recorded sound, with 273 million units sold annually compared to 125 million prerecorded cassette tapes. The compact disc sold slowly, beginning with 800,000 units shipped in 1983 and rising to 53 million in 1986. By that time, the cassette tape had taken the lead, with slightly fewer than 350 million units. The vinyl record was in decline, with only about 110 million units shipped. Compact discs first outsold vinyl records in 1988. In the ten years from 1979 to 1988, the sales of vinyl records dropped nearly 80 percent. In 1989, CDs accounted for more than 286 million sales, but cassettes still led the field with total sales of 446 million. The compact disc finally passed the cassette in total sales in 1992, when more than 300 million CDs were shipped, an increase of 22 percent over the figure for 1991. The introduction of digital recording had an invigorating effect on the industry of recorded sound, which had been unable to fully recover from the slump of the late 1970’s. Sales of recorded music had stagnated in the early 1980’s, and an industry accustomed to steady increases in output became eager to find a new product or style of music to boost its sales. The compact disc was the product to revitalize the market for both recordings and players. During the 1980’s, worldwide sales of recorded music jumped from $12 billion to $22 billion, with about half of the sales volume accounted for by digital recordings by the end of the decade. The success of digital recording served in the long run to undermine the commercial viability of the compact disc. This was a playonly technology, like the vinyl record before it. Once users had become accustomed to the pristine digital sound, they clamored for digital recording capability. The alliance of Sony and Philips broke down in the search for a digital tape technology for home use. Sony produced a digital tape system calledDAT, while Philips responded with a digital version of its compact audio tape called DCC. Sony answered the challenge of DCC with its Mini Disc (MD) product, which can record and replay digitally. The versatility of digital recording has opened up a wide range of consumer products. Compact disc technology has been incorporated into the computer, in which CD-ROM readers convert the digital code of the disc into sound and images. Many home computers have the capability to record and replay sound digitally. Digital recording is the basis for interactive audio/video computer programs in which the user can interface with recorded sound and images. Philips has established a strong foothold in interactive digital technology with its CD-I (compact disc interactive) system, which was introduced in 1990. This acts as a multimedia entertainer, providing sound, moving images, games, and interactive sound and image publications such as encyclopedias. The future of digital recording will be broad-based systems that can record and replay a wide variety of sounds and images and that can be manipulated by users of home computers.

13 May 2009

Community antenna television


The invention: 

Asystem for connecting households in isolated areas to common antennas to improve television reception, community antenna television was a forerunner of modern cabletelevision systems.

The people behind the invention: 

Robert J. Tarlton, the founder of CATV in eastern Pennsylvania
Ed Parsons, the founder of CATV in Oregon
Ted Turner (1938- ), founder of the first cable superstation,WTBS