HISTORICAL DEVELOPMENT OF COMPUTERS
COMMUNICATION
Communication is an important human activity. It is responsible for the development of cultures and their evolution or downfall. During the industrial revolution new communication techniques began to evolve. Telegraph, telephone, radio, television were developed in a relatively short period of time. Communication equipment and techniques are still being developed and improved.
The main elements in any communication process are a message source, a message medium and a receiver. Noise is an important concept in communication theory. It is determined in communication theory as any signal that interferes with the message being transmitted. Radio static is a form of noise. Dirt on camera lens is noise also.
In 1875 Alexander Graham Bell invented the telephone. In the 20th century the number of telephones in use in the world grew at almost 100 percent per decade. A great contribution to long-distance communication came with the development of wireless technology. Before the First World War wireless telegraphy was established as a means of regular communication with ships at sea. In the next few years the telephone systems of all the countries were connected with each other by radio. The inventor of the radio was the Russian scientist A.S. Popov.
Nowadays we live in era, when information is the key and engine of progress. Our society needs the perfect means of information exchange. That is why today the Internet, cell phones, radio, television as the popular means of communication are under permanent development.
DEVELOPMENT OF ELECTRONICS
Electronics is a field of engineering and applied physics dealing with the design and application of electronic circuits. The operation of the circuits depends on the flow of electrons for generation, transmission, reception and storage of information.
The invention of the vacuum tubes at the beginning of the 20th century was the starting point of the rapid growth of modern electronics. The development of vacuum tubes where the electrons flow through the vacuum made possible the progress in radio communication technology before the World War II and in the creation of early computers during and shortly after the war.
The transistor invented by American scientists W. Shockly, J. Bardeen and W. Brattain in 1948 completely replaced the vacuum tube. The transistor, a semiconductor device with three electrodes, had great advantages over the best vacuum tubes. It performed the same functions as the vacuum tube but at reduced weight, size, power consumption and with high reliability. With the invention of the transistor all the essential circuit functions could be carried out inside solid bodies. Early transistors could respond at a rate of a few million times a second. This was fast enough to serve in radio circuits, but far below the speed needed for high-speed computers or microwave communication systems.
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The progress in semiconductor technology led to the development of the integrated circuit. There appeared a new field of science – integrated electronics. It greatly reduced the size of devices, lowered manufacturing cost and at the same time provided high speed and increased reliability.
Today it is difficult to imagine our life without electronics. Electronic devices are widely used in scientific research and industrial designing; they control the work of plants and power stations, calculate the trajectories of space ships and help the people discover new phenomena of nature. Automation of production processes and studies on living organisms became possible due to electronics.
VACUUM-CHANNEL TRANSISTORS
In 1947 William Shockley, John Bardeen and Walter Brattain invented the first transistor at Bell Laboratory. By the mid-1970s, the only vacuum tubes you could find in Western electronics were used in certain kinds of specialized equipment. Today even those are gone, and vacuum tubes are an extinct technology. So it might come as a surprise to learn that some changes to the fabrication techniques could breathe vacuum electronics back to life.
At the NASA Research Center the scientists are working to develop vacuum-channel transistors. Their research is still at an early stage, but the prototypes show that this new device holds extraordinary promise. Vacuum-channel transistors work 10 times as fast as ordinary silicon transistors and may eventually be able to operate at high frequencies. And they are considerably more tolerant of heat and radiation.
The vacuum-channel transistor is the combination of traditional vacuum-tube technology and modern semiconductor fabrication techniques. This curious hybrid combines the best aspects of vacuum tubes and transistors and can be made as small and as cheap as any solid-state device. Indeed, making them small is what eliminates the well-known drawbacks of vacuum tubes. In a vacuum tube an electric filament is heated sufficiently for it to emit electrons. That is why vacuum tubes need time to warm up and so they consume too much power. But vacuum-channel transistors do not need a filament or hot cathode. If the device is made small enough, the electric field across it is sufficient to draw electrons from the source by the process known as field emission. It makes this new kind of a transistor energy efficient.
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Although the scientists are still at an early stage with their research, they believe that the improvements they've made to vacuum-channel transistor could have a huge influence on the electronics industry, particularly for applications where speed is of special importance. These transistors might also find their way into future microprocessors. But a great deal of work remains to be done before we can see commercial products emerging.
HISTORY OF TELEVISION
Television, TV for short, is a telecommunication medium that is used to transmit and receive moving images, either monochromic or color, usually accompanied by sound. The word television has been derived from Latin and Greek words which mean “far sight”. The invention of television was the work of many individuals in the late 19th century and early 20th century. Individuals and corporations competed in various parts of the world to deliver a device that superseded previous technology.
The early stages of television development saw inventors employing a combination of optical, mechanical and electronic technologies to capture, transmit and display a visual image. In the late 1800s the first images were transmitted electrically via early mechanical fax machines. In 1884 a 20-year old German student Paul Gottlieb Nipkow patented the first electromechanical television system that used a scanning disk with series of holes spiraling towards the centre. These holes were located at equal intervals in such a way that the disk would allow light to pass through each hole in a single rotation and onto a light sensitive selenium sensor which produced electrical pulses.
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With time came up designs that used a mirror-drum scanner to capture the image and cathode ray tube (CRT) as a display device. In 1907 a Russian scientist Boris Rosing used a CRT in the receiver of an experimental television system. In 1925 Scottish inventor John Logie Baird exhibited the transmission of moving silhouette images in London. In 1927 Baird became the first person to invent a video recording system called “Phonovision”. A few of his “Phonovision” recordings were decoded and renewed in 1990s using modern digital signal-processing technology.
The mountains of Pennsylvania gave birth to the cable television in 1940. The second major development of television in the 1960s was the introduction of color in 1964, a revolution that transformed the world. For the first time, audiences could see shows, musicals, documentaries, and news broadcasts as if they were right there. On July 20, 1969 as many as 600 million people watched the first transmission from the Moon. By 1972 around 50% of the televisions used in homes were colored.
Digital television started in the late 2000s. It was an innovative service that represented the first significant evolution in television technology since color television in the 1960s. Initially the adoption rate was low. But soon, more and more households were converting to digital televisions.
Digital television (DTV) is the transmission of audio and video by digitally processed and multiplexed signal, in contrast to analog signals used by analog television. Digital TV can support more than one program in the same channel bandwidth.
Advent of digital television allowed innovations like smart TVs. A smart television, sometimes referred to as connected TV or hybrid television, is a television set with integrated Internet and Web features, and is an example of technological convergence between computers and television sets.
The future of TV will be very different from the first years of the history of television.
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INTERNET VS TELEVISION
Do you spend more time in front of the TV or in front of the computer screen? Just a few years ago, the answer probably would have been the television. But with a growing global online population, the Internet is gradually replacing television in the lives of the modern individuals.
Recent studies show that about 30% of the worlds’ population is online, and the average Internet user spends 32 hours per month surfing the Web. While many individuals still watch television on a regular basis, more and more people choose to view content online.
According to a study, Russians spend about 98 minutes a day watching television. But time spent online is starting to surpass time spent watching television. Unlike TV, the Internet can be used for business, personal use, and entertainment.
Cable and satellite TV services may provide thousands of channels, but traditional television programming can’t be compared to the variety of the Internet. There are hundreds of TV shows and movies available from a number of online sites. And with huge databases like YouTube, you can find practically any program ever filmed.
Another advantage of the Internet is flexibility. Viewers can watch TV anywhere they want on a variety of portable devices, from laptops to tablets and smartphones. And with such Internet connections from providers like Google Fiber and Verizon Internet, viewers can multi-task while they watch TV. They can send emails. Look up information. Scan social media accounts. Shop online.
Social media makes watching TV online even more appealing – viewers can tweet or post about the programs they watch, interact with other viewers and share opinions about characters. In modern world where users can keep up with the weather, their family and friends, consumers have less and less of a reason to turn on the TV.
There is no denying that television is still a major player, but the Internet is quickly becoming the dominant force in entertainment. The recent domination of the Internet over TV also proves that viewers want to create and continue conversations online.
HISTORICAL DEVELOPMENT OF COMPUTERS
We are living in the computer age. Most of our jobs are being influenced by the use of computers. In the areas of science and technology no improvements can be achieved without the use of computers. Computer is an electronic device that performs complicated calculations at high speed. The first computing machine was developed by Charles Babbage in the 19th century. It contained the basic elements of an automatic computer and performed computations according to the sequence of instructions. Another important contribution to the development of the computer was made in the mid-1800s by George Boole who devised a system of formulating logical statements symbolically. During the 1940s the American mathematician John Von Neumann was the first to use stored programme concept in computers.
The rapidly developing field of electronics led to the construction of the first generalpurpose electronic computer in 1946. The device contained 18,000 vacuum tubes and had a speed of several hundred multiplications per minute. The computers were extremely large in size with vacuum tubes which generated considerable heat. Hence, special air conditioning devices were required to dissipate this heat. They were extremely slow and their storage capacity was about 2000 words. In these computers punched cards were used to enter data into the computer.
Later transistors appeared. The use of transistors in computers reduced the heat generated during the operation. It also decreased the size and increased storage capacity. Computers required less power to operate and were much faster than the first generation computers. They used high level languages for writing computer programs.
The third generation computers started in 1966 with the invention of integrated circuits (IC). They had small size and were cost effective. Storage capacity and speed of these computers were increased many folds compared to the second generation computers.
The fourth generation computers were introduced after 1976 and in these computers electronic components were further miniaturized through Large Scale Integration (LSI) techniques.
A digital computer is a system composed of five elements: input devices, memory storage devices, a central processing unit, output devices and a communication network called a “bus” that links all the elements of the system and connects the system itself to the external world.
Today we are at the threshold of the new computer era when artificial intelligence could be invented. There are no questions with “if”, the only question is “when”. And time will show whether computers will become our best friends or our evil enemies.
OPTICAL COMMUNICATION
The use of visible waves or light for communication has been common for many years. As early as 1880 Alexander Graham Bell could transmit the human voice using a light beam. The photophone invented by Bell four years after the invention of telephone was used to transmit speech over a distance of 200m. However, although the investigation of optical communication continued in the beginning of the 20th century its use was limited. This was due to both the lack of suitable light source and the problem that light wave transmission in the atmosphere was affected by disturbances such as rain, snow, fog, dust and atmospheric turbulence.
A renewed interest in optical communication was stimulated in the early 1960s with the invention of the laser. This device provided a powerful coherent light source and made free space optical transmission possible. But because of the problems with light transmission in the atmosphere these systems were limited to short distance applications.
Nevertheless, the invention of the laser led to the research of optical components to achieve reliable information transfer. The proposals for optical communication via optical fibers fabricated from glass to avoid degradation of the optical signal by the atmosphere were made in 1966 by Kao, Hockham and Werts.
An optical fiber communication system is similar in basic concept to any type of communication system. Conventional communication transmission is based on the conduction of electrons through metal. But optical communication systems substitute photons for electrons and glass fibers for copper.
There are a lot of advantages of optical fibers over electric conductors. Optical fibers are far smaller and much lighter than corresponding copper cables. They are immune to electromagnetic and radio frequency interference. Optical fibers have very low transmission loss in comparison with the best copper conductors. This low-loss property reduces the requirement for intermediate repeaters or amplifiers to boost the transmitted signal strength. Today optical fiber has become the dominant transmission medium in the major industrialized societies.
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