BLUETOOTH
Overview
- Why?
- What?
- How?
- Where?/ When
Why Bluetooth?
- It is a cable-replacement technology
- ”Bluetooth” comes from Denish Viking King’s name
What is Bluetooth?
- Bluetooth is a low-power, short-range wireless networking standard designed for local area voice and data communications.
- Bluetooth tech. redefines the very way we experience connectivity.
How it comes?
- The Original idea....
- Bluetooth is a standard for a small, cheap radio chip to be plugged into computers, printers, mobile phones, etc.
- Now....
- To transmit data between everywhere
Where it works?
- Everywhere
- You define the boundaries of your productivity where your business may take you.
Bluetooth Technology
- Why?
- What?
- Who?
- Where?/ When?
Why it’s wireless?
- Bluetooth uses omni-directional radio waves in the unlicensed ISM band at 2.4GHz that can transmitted through walls and other non-metal barriers.
- Bluetooth uses 1600 times/s frequency hopping to avoid interference
What’s the advantage & disadvantage ?
Advantages :
- Wireless;
- Signal-robustness;
- Power-efficiency;
- Synchronous real-time conversation and data transitions
Disadvantages :
- Short-range;
- Relatively high cost;
- Relatively low transfer rate (712Kbps)
Who makes it work?
- Bluetooth wireless tech. is supported by producta & application development in a wide range of market segments.
Who makes it work (continue) ?
- software developers
- silicon vendors
- peripheral & camera manufacturers
- mobile PC manufacturers
- handheld device developers
- consumer electronics manufacturers
- car manufacturers
- test & measurement equipment manufacturers
Where is Bluetooth?
- SIG --- Special Interest Group
- 3Com Agere Ericssion IBM Intel
- Microsoft Motorola Nokia Toshiba
Bluetooth in our daily life..
- in the Office
- in the Home
- on the Road
- in the Soical settings
Bluetooth in the Office..
- Personal Digital Assistance ßàdesktop PC
- PDAßà electronic board
- machineßà PDA/laptop
Some Examples For Bluetooth in office :
Bluetooth in the Home
- door,lights,air-conditioning are all Under your control
- look after Your children
- PDAßàelectronic bulletin board
- security system
Some Examples For Bluetooth in home :
Bluetooth on the Road
- book and confirm your tickets
- make ”free” internet voice call with internet port
- rent cars, order hotel...
- check-in automatically; enter your room without unlocking the door
Some Examples For Bluetooth on the Road :
Bluetooth in the Car
- when go out for travel, a map appears in your display
- door unlocked, radio tunes searched, seat adjusted automatically
- daily reminding
- receive messages via speakerphones
Some Examples For Bluetooth in the car :
Bluetooth in the Social settings
- book movie tickets --- get preferred seats
- win your bets om racetrack
- exchange info. in your business
Some Examples For Bluetooth in the Social Settings:
Bluetooth Products
- Bluetooth’s main competition is a piece of wire
- In order to get wider market, the cost of its componets must be low
- Take a look at some bluetooth products in markets
New millennium, slipped from second to third millennium of the Christian era has resulted reflections and effects on the collective psychology in many countries. However, the arrival of a "new millennium" is not just a chronological convention own calendar of Western culture. It has to do with the so-called Christian era, which starts from the year in which it is assumed that Jesus Christ was born. Other cultures, like Islam, establish a different year for the start of his era and, therefore, according to their calendar are not on the threshold of a new millennium. The beginning of the century, and therefore the third millennium, will take place in a world that is experiencing a rapid transformation in all areas. The changes affect the entire world and brought to a future increasingly prosperous and interconnected, but also threatened by significant challenges and serious problems.
The scientific and technical progress
The progress of science and technology has remained, since the second half of the twentieth century, a phenomenal pace. The results of scientific research and technology have become standard elements in everyday life, to the point that half of the products commonly used by humanity were unknown at the end of World War II in 1945. This process, which some experts have described as scientific and technological revolution has not just begun, and if no important developments will remain a feature of the civilization of the new millennium. There are many areas where progress can be focused to provide: the science of new materials, robotics or food technology may be some of the key. But there are three areas of research that should be highlighted as lines of unstoppable progress of a future: electronics, space exploration and genetic engineering.
Today, computers are involved in a true "information revolution" that affects decisively a society increasingly digitalised. This allows, and will increasingly, a genuine transformation of all aspects of daily life and economy of both the productive and the services. Aerospace research is becoming a reality ever closer conquest of space. It is expected to be established stations inhabited by humans permanently in space. Since announcing tours to outer space and it seems that in less than a century, traveling to the Moon will be within reach of many citizens.
In the field of biological research, the discovery of deoxyribonucleic acid (DNA) in the middle of the twentieth century and the subsequent development of genetic engineering will call in the coming decades, spectacular advances. Many diseases can reach an explanation in the genetic structure of humans and this will facilitate their recovery, will allow the establishment and modification of new organisms by appropriate genetic alteration, which will be a revolution in agriculture and livestock. The new genetics involves undoubtedly unquestionable advantages, but is subject to limits of ethical responsibility in their development.
The communications revolution
The extraordinary progress in communication techniques and information can be compared to the birth of writing or printing. As in these two events, the communications revolution leads to the formation of a particular culture that has, on this occasion, a universal character that will become a sign of the new millennium. The communications revolution makes it possible to see in real time, wars, sports and cultural events, and all kinds of events. Millions of people living in places far apart, can hear a song and a conference simultaneously. Access to information makes it through the Internet or other computer networks, it is possible to quickly obtain more information from any field of science or culture that until a few years ago would have been impossible to imagine. The improvement of these planetary networks, fruit of the so-called information revolution, in a few years will be available in every home access to the major film archives, libraries, newspaper and even retail outlets.
The progress of communications and the rise of information society has led to unprecedented technological race, motivated by the desire to dominate the world of communication. The winner of this race is still America, but all developed countries are investing huge sums in this field.
A Global World
In the last years of the twentieth century has been a number of phenomena in nature "global" that would have been unthinkable a few decades earlier. A set of behaviors, tastes and values are now shared by millions of people belonging to different cultures. The media have reduced the physical distances and different times have made be lived together before the television screens or to a particular consumer product. Globalization is a relatively recent phenomenon and is difficult to estimate its impact on the XXI century. However, there are three areas where their influence is enhanced significantly: the economy, politics and culture. Globalization has its precise scope in the world economy, especially in commercial levels, financial and organizational, where it functions as an efficient way. Economic globalization is an absolute freedom of trade. With it, the production of goods is limited only by physical or geographical advantages, firms are organized in a very flexible way to have better access to global markets while the financial market is decentralized, has a instant escape the influence of governments.
In the field of politics, globalization affects the structure of government and policy decisions. In a global world, the sovereignty of states seems to be fading, they create multiple centers of power and international organizations are significantly increased their importance.
The culture is affected in many ways by the process of globalization. The creation of large symbols are global. There is a tendency to cultural diversity and the triumph of a cosmopolitanism that goes beyond the states themselves. The information has not only locally and is broadcast in a very fast worldwide. Leisure and tourism grow to unimagined levels. The instruments of globalization and cultural connection, such as the Internet (one of the most significant phenomena of the late twentieth century), multiply and forced to devise new ways of learning. Globalization is a new phenomenon, which affects the structure of corporations, governments and cultural formations: it is full of interesting questions and answers are still uncertain. The new millennium will be shaping the new global workplace and perceive.
The problems of the new millennium
However, in this new world with more technologically developed and per capita production capacity of which existed at any other time in history, mankind has to face serious problems, the most prominent of which are as follows. The existence of a dual world: first, the gap between rich and poor, on the other, inequality of wealth within societies of rich countries. Over three quarters of humanity live in countries that have not reached a sufficient level of development and most of its inhabitants can barely survive. These countries are in South America, Asia and Africa. Among them there are great differences: some are in developing countries, but others live in poverty. Hunger, disease and illiteracy are serious social problems affecting most of the inhabitants of these countries. In the world immediately before the start of the third millennium, more than 800 million people go hungry and feed 500 million inadequately. The degenerative diseases caused by malnutrition, continue to rage. In the poorest countries on Earth, is illiterate, on average, 60% of the population. This means that most human beings are deprived of education.
The societies of rich countries are emerging within it a set of serious problems among which social exclusion. In developed societies poverty mainly affects long-term unemployed who no longer collect unemployment insurance. Next to these immigrants (especially those from Third World countries) and women are the protagonists of poverty at the turn of the century. There a more tragic poverty, the poorest of the poor people homeless, marginalized by the drug and many foreign immigrants, the cities of the industrial world are constantly increasing the number of these people.
Paradoxically, a high number of migrants flocking to the borders of rich countries in search of better living conditions. The rise of intolerance and racism in developed countries makes many foreigners who come from countries get poor and marginalized groups, sometimes persecuted.
The collapse in 1991 of the Union of Soviet Socialist Republics (USSR) and the governments of the countries of the orbit of this has been a new challenge for the XXI century. The former communist countries have seen their economic systems and fall face difficult transitions to different forms of economic and political management. This transformation entails serious social problems that add to the misery to many of its inhabitants.
The serious problem of consumption and drug trafficking is reaching unimaginable heights among younger segments of many developed countries. Along with this there is the fear of new infectious diseases such as acquired immunodeficiency syndrome (AIDS), which affects so brutal to poor countries, but not only them. These new outbreaks are in addition to other traditional ones such as malaria, which still produces nearly three million deaths each year in African populations, Asian and South American.
The danger of unchecked industrial development, which has already caused serious ecological problems, remains in this new century is a risk that threatens irreparable degradation of the environment. The conflicts are still a common experience in certain parts of the world. Wars between countries or civil wars that may be considered cause suffering and death of many thousands. Among the areas of conflict are ongoing Middle East, the Balkan peninsula and many African countries.
Finally, although democracy has come to be regarded as the "least bad" of political systems, countries that enjoy it are far from meeting the aspirations of its citizens. The criticism that this raises, performed largely by prominent representatives of politics and for many of the militants in the new social movements are based on a desire to redefine the principles of political participation, management of the affairs of State and build more just societies.
No wonder that the new millennium generate sometimes a pessimistic view about the future. However, there is the presence of some reasons for hope: the technological development has allowed the improvement of living conditions of millions of men and women, while democratic rights are spreading and allowing higher levels of equality and freedom in many nations.
But above all, include the gradual increase of human solidarity that arises spontaneously and is necessary in the presence of serious problems affecting the contemporary world. Will the combination of a genuine spirit of solidarity and equal and constant criticism to any excess of power and to the injustice that allow to build a better century. And in this task are determined, fortunately, millions of men and women, many of them activists of so-called NGOs.
In 1667, Robert Hooke invented the telephone cord. Almost everyone has ever two cans connected with string tie and sent messages through it. However, a device is impractical and besides no good for long distances. In 1854 the French inventor Charles Bourseul raised the possibility of using vibrations caused by the voice on a floppy disk or diaphragm, in order to activate and deactivate an electrical circuit and produce similar vibrations in a diaphragm located in a remote location, which would reproduce the original sound. Some years later, the German physicist Johann Philip Reis invented an instrument conveying musical notes, but could not reproduce the human voice. In 1877, having discovered that to transmit voice could only be used direct current, the Scottish-born American inventor Alexander Graham Bell built the first phone capable of transmitting and receiving human voice in all its quality and timbre.
Magnetic Phone Bell
Two Americans, working independently, invented the telephone almost simultaneously. Recall that Alexander Graham Bell invented the telephone because I get to the patent office only hours before Elisha Gray on February 14, 1867. Bell support the findings of several scientific and based his system on the electromagnet's core set of his invention consisted of a transmitter, a receiver and a single cable. The sender and recipient were identical and contained a flexible metal diaphragm and a horseshoe shaped magnet inside a coil. The sound waves that impinged on the diaphragm is vibrated within the field of the magnet. This vibration induces an electric current in the coil, which varied according to the vibrations of the diaphragm. The traveling oriented cable to the receiver, where fluctuations generated magnetic field strength of it, making the diaphragm vibrate and reproduce the original sound. Bell actively promoted your phone. He shows throughout the United States and also in England and France, which unlike other countries were not too excited and continue to serve as messengers. The phone's sound quality was poor, the system no good for long distances and very expensive.
On the other hand, had invested heavily in the telegraph and investors clearly would not support an invention that could ruin their businesses.
The older phones using a single device as transmitter and receiver. Its basic components were a permanent magnet with a coiled cable that made him and a thin coil of cloth and metal diaphragm subjected to the force of the magnet. The strength of the voice, as snide waves, caused a movement of the diaphragm, which in turn generated a very small alternating current in the wires of the electromagnet. These teams were able to reproduce the voice, though so faintly that were little more than a toy.
The invention of the carbon telephone transmitter by Emile Berliner is key in the development of useful phone. It consists of a carbon granules placed between a sheet metal called electrodes, one of which is the diaphragm, which transmits pressure variations to these granules. The electrodes conduct electricity flowing through the carbon. The pressure variations in turn give rise to a variation of the electrical resistance of carbon. Through the line current is applied to the electrodes, and the resulting current also varies. The fluctuation of the current through the carbon transmitter results in a higher power that's inherent to the original sound wave. This effect is called amplification, and is of crucial importance, since until then an electromagnetic transmitter was only capable of converting energy, and always produced a lower power than that contained in the sound wave.
Mobile post
In the recipients of the latest phones, the imam Step to be flat as a coin and the magnetic field acting on the diaphragm of iron was of greater intensity and consistency. The transmitters were very thin diaphragm mounted beneath a perforated grid. In the center of the lens had a small container with carbon granules. The sound waves passing through the grid cause a swing of the receptacle. In the downswing, the granules are compacted and produce an increase in current through the transmitter.
Since the carbon transmitter was not practical when converting electrical energy into sound pressure, the phones have evolved into separate receivers to the transmitters. This provision allows you to place the transmitter near the mouth to collect the maximum sound energy, and the receiver in the handset, which eliminates the annoying background noise. In these phones, the receiver was still a permanent magnet with a coil of wire, but with an aluminum diaphragm subject to a metal part. The design details have made dramatic improvements, but the original concept continues to allow robust and efficient equipment.
Current Phones
The electrical equivalent of the permanent magnet is a plastic substance called electret. As a permanent magnet produces a permanent magnetic field in space, an electret generates a permanent electric field in space. As an electrical conductor moving within a magnetic field induces a current, the movement of an electrode within an electric field can produce a change in voltage between a mobile and a stationary electrode on the opposite side of the electret. Although this effect was known of old, it was only a laboratory curiosity until the appearance of materials capable of retaining an electrostatic charge for years. Current telephone transmitters are now based on this effect, rather than the change in resistance of carbon granules in terms of pressure.
Today, carbon microphones have been replaced by electret microphones, which are smaller, cheaper, better reproduce sound and are more robust than the former. The signal amplification is achieved using electronic circuits (transistors and / or integrated circuits). The receiver is normally a small diameter speaker, either vibrating diaphragm or cone.
Parts of telephone apparatus
The handset consists of a transmitter, a receiver, an audible alarm, a device and a circuit marker suppressor local effects. If this is a two-piece device, the transmitter (microphone) and receiver (receiver) are mounted on the handset, the ringer is in the base and the markup and the local effects suppressor circuit can be in any of the two parties, but usually go together. More complex phones can lead to a microphone and a speaker in the base part, apart from the transmitter and receiver in the handset. In wireless phones, the handset cord is replaced by a radio link between it and the base, although still a cable to the line. The cell phones are usually one piece, and miniature components allow you to combine the base, the headset microphone and a portable component that communicates with a remote station radio. No online or cables needed for the handset.
The audio alarm phone ring is often referred to, reference to the fact that during most of the history of these teams the alarm function is provided by an electric bell. The creation of an electronic substitute for the bell, capable of creating a pleasant sound while distinctive at a reasonable cost, was a surprisingly difficult task. For many, the sound of the bell is still preferable to an electronic buzzer. However, since the mechanical bell requires some physical volume to be effective, the trend towards smaller teams increasingly demand the use of electronic alarms in most phones. The gradual replacement of the bell will also change in the near future, the current method of activating the alarm 90 volts alternating current (V) and 20 hertz (Hz) to the line-by techniques of lower voltages, more compatible with transistorized phones. Something similar is occurring with the marking scheme phones.
The dial has gone through a development over its history. There are two ways of marking, and pulse or tone multifrequency. The pulse system is based on a hard marker. The dial has a very ingenious mechanical design, consists of the numbers 1 to 9 followed by 0, arranged in a circle below the hole and drilled a moving disk. Place the finger in the hole corresponding to the number chosen and the disc is rotated in the direction of clockwise until you reach the top and then release the disc. A spring forces the disk to return to its starting position while rotating, opening and closing an electric switch as many times as you turn the disk to dial the number chosen. In the case of 0 is made 10 starts, since it is the last number of the disk. The result is a series of pulses called the electrical current flowing between the telephone and the switchboard. Each pulse has an amplitude equal to the voltage supplied by the switchboard, usually 50 V, and lasts about 45 ms (milliseconds, thousandths of a second). Switchboard equipment have these pulses and determine the number you want to dial.
The electrical pulses produced by the rotating disc are ideal for controlling switch gear step-by-step of the first automatic switching centers. However, mechanical marking is a major source of maintenance costs, and the disk marking process is slow, especially in the case of long numbers. The availability of cheap and reliable amplification transistor advised that brought the design of a marking system based on transmission power of tones rather small, rather than the pulses of high power marking. Each button on a multi-keyboard controls the sending of a pair of shades. It uses a coding scheme "2 7" on the first pitch corresponds to the normal row of a matrix of 12 buttons and the second column (4 rows 3 columns need 7 tones).
Today, most phones are hard buttons instead of dialing and uses a system of tones. The modern telephone exchanges are designed to receive ringtones, but for many years because the system pulses the only one available and there are still phones of this type, the plants can continue to receive pulses. As a user who buys a phone may have an old line not yet support multi-frequency signals, the phones have a switch button to select the sending of pulses or tones.
There is an important functional element of the phone that is invisible to the user: the local effects suppressor circuit. The people control the tone of voice when speaking and adjust the volume accordingly, a phenomenon called "local effect". In the first phones, the receiver and transmitter were connected directly to each other and the line. This meant that the user could hear his own voice through the receiver with much greater intensity than when it was not pressed to his ear. The sound was much stronger than normal because the carbon microphone amplifies the sound energy while the converts to electrical noise. In addition to being unpleasant, this meant that the user go down the voice volume when speaking, making it difficult to listen to the receiver.
The first circuit containing a transformer suppressor along with other components whose characteristics depend on the electrical parameters of the telephone line. The receiver and transmitter were connected to different "ports of the circuit" (in this case, different windings of the transformer), but not each other. The suppressor circuit transfers energy from the transmitter to the line (although some also to other components), but nothing happens to the receiver. This eliminates the feeling that one cries out in his own ear. Currently, the transmitter and receiver are isolated from each other, separated by electronic circuits that completely eliminate the "local effect".
Telephone exchange
At first, the phone simply plugs into two homes or offices to one another; He bought the phone and consequently a line was purchased privadaa own. There was no way to connect a phone to pair another pair. After centrals were built and installed to stop allowing such connection: lass centrals manuals, run by people called operators.
Central manuals
In the first cell, the current was generated by a battery. The local circuit also had the battery and transmitter, a transformer winding, which is called the induction coil, the other winding, connected to the line, raised the voltage of the sound wave. The connections between phones were either manual, by switchboard operators who worked at headquarters located in switching or exchanges.
As telephone systems were developed, the manual connections began to be too slow and laborious. This was the trigger for the construction of a series of mechanical and electronic devices that enable automatic connections (see Electronics).
Automatic Power
Almon B. Strowger, an undertaker, automatic design a cental which was patented in 1891. But the big question was how could the phone to indicate the central number. The doctor came to settle the question. By dialing the number will produce a series of electrical impulses that reach the central and trigger a special switches (selectors) that connect to the desired number
The first automatic central install the world of La Porte, Indiana, in 1892, but the wonderful invention of Strowger spread slowly, since it took 16 years before the inauguration of the first in Europe, particularly in Munich. In England we had to wait until 1958 for the first plant was installed automatic intercity service in Bristol, because then I could not dial directly from one city to another, but needed to call the operator to establish communication.
Crossbar switching
The centrals have undergone considerable improvements in telephones and tested many different systems. One of the most successful which is the crossbar switching. It is also an electromechanical system, but can handle multiple calls simultaneously.
Existing plants
Currently, there are virtually no longer seen by switchboards phone manuals. All subscribers are served by automatic exchanges. In this type of plant, the functions of human operators are performed by switching equipment. A relay of line current of a circuit replaced the switchboard light of the switchboard, and a crossover switch serves as the cables.
Electronics equipment in central switching the handle to automatically translate the dialed number, either by pulses or system of tones, and route the call to its destination.
The phone call begins when the person lifts the handset and wait for the dial tone. This causes the closing of an electric switch. The closing of the switch activates an electrical current flow through the line of the person making the call, between the location of it and the building housing the PABX, which is part of the switching system. This is a current that does not change its flow direction, although it can do its intensity or amplitude. The plant detects this current and returns a dial tone, a particular combination of two notes to make it perfectly detectable by both teams as by people.
Having heard the ringing tone, the person makes a series of numbers using the buttons on the handset or the base team. This sequence is unique to another subscriber, the person called. The switching equipment of the plant removes the dial tone of the line after receiving the first number and, after receiving the last, determines whether the number you want to connect central part of the same or a different one. In the first case, apply a series of intervals current line call to the call recipient. The current call is 20 Hz alternating current, which flows in both directions 20 times per second. The phone user has an audible alarm that meets the current call, usually with a perceptible sound. When the phone is answered by lifting the handset, begins to circulate a steady stream of line that is detected by the plant. It fails to apply the current call and establishes a connection between the caller and the call, which is what allows us to talk.
Call Centers are a hierarchical network. If the code of the dialed number does not belong to the same plant, but belongs to another center at the same level and geographic area, establishing a direct connection between the two stations. However, if the dialed number belongs to a distinct branch of the hierarchy have to make a connection between the first central switching center that higher-level common to both and between it and the second facility. Switching centers are designed to find the shortest path available between the two stations. Once the connection between the two stations is established, the second central alarm activates the corresponding receptor as if it were a local call.
Automatic relay stations are being replaced by computer-controlled digital exchanges. Solid state technology has allowed these plants to process calls in a time of one millionth of a second, so you can process large amounts of calls simultaneously. The input circuit becomes, first, the caller's voice to digital pulses. These impulses are then transmitted through the network via high capacity systems, which connect the different calls based on computerized mathematical operations switching. The instructions for the system are stored in computer memory. The equipment maintenance is simplified thanks to the duplication of components. When a failure occurs, operation automatically enters a standby unit to handle calls. Thanks to these techniques, the system can make quick calls, both local and long distance, quickly finding the best available route.
Routes of transmission
Early telephone systems used by heavy steel cables or copper to keep the intensity to transmit the electrical signal. However, one kilometers of cable weighing 170kg, so very solid poles were needed to sustain them.
According increased the LENGTH of the lines, would that received attenuated to become completely unintelligible.
To avoid this, PROMPTED century began to settle in the circuitry telephones some devices called loading coils. These amplify the signal could not keep to a minimum but if lass lost along the line.
Obviously, he must locate a way to amplify signals lass credibility and convey them with the maximum intensity. This will repeaters, by which were no longer needed and these cables so thick they could lay under the soil surface.
However, as call volume and the distance between switching centers grew, it became necessary to use other routes of transmission. The most commonly used are the submarine coaxial cable, by radio (either by microwave or satellite) and fiber optics today. The connection between telephone exchanges and subscribers are still performed using a pair of copper wires to each subscriber. However, in some large cities have already started replacing them by fiber optics.
Telephony carrier wave
Using frequencies above the range of voice, ranging from 4,000 to several million cycles per second, or hertz, can be transmitted up to 13,200 telephone calls simultaneously by the same driver (coaxial cable, submarine cable, and microwave). Techniques telephony carrier wave are also used to send phone messages through normal distribution lines without interfering with the regular service. Due to the growing size and complexity of systems, using solid state amplifiers, called repeaters, to amplify the signal at regular intervals.
Coaxial cable
The coaxial cable, which appeared in 1936, uses a series of drivers to support a large number of circuits. The modern coaxial cable is manufactured with copper tubes of 0.95 cm in diameter. Each of them has, right in the center of the tube, a fine copper wire attached with insulating plastic disks spaced about 2.5 cm. The tube and wire have the same center, ie are coaxial. Copper tubes protect the transmitted signal of possible electrical interference and prevent energy loss by radiation. A cable, consisting of 22 rings arranged in coaxial tubes embedded in polyethylene and lead, can carry 132,000 simultaneous telephone conversations.
Submarine Cables
Transoceanic telephone service was introduced commercially in 1927 using radio transmission. However, the problem of amplification stopped laying telephone cables until 1956, when it first entered service on transoceanic submarine telephone cable in the world, connecting Newfoundland and Scotland using coaxial cables.
Microwave Mobile
In this method of transmission, radio waves are at the very high frequency band, and microwave are called, are used as carriers of telephone signals and transmitted from station to station. Since the microwave transmission requires an expeditious way between source and receiving station, the average distance between relay stations is about 40 km. A microwave channel can transmit up to 600 telephone conversations.
Satellite Telephony
In 1969 he completed the first global telephone network based on a series of satellites in stationary orbits at a distance from Earth of 35,880 km. These satellites are powered by solar cells. Calls transmitted from a terrestrial antenna on the satellite are amplified and relayed to ground stations away. The integration of satellites and ground equipment allows direct calls between different continents as easily as between close proximity. With digitization of broadcasting, the satellites in the Intelsat global series can broadcast up to 33,000 calls simultaneously, and different TV channels.
A single satellite phone will not serve to make a call, for example, between New York and Hong Kong, but two other. Even taking into account the cost of a satellite, this route is cheaper to install and maintain the route channel equivalent using coaxial cables lying on the seabed. Consequently, for large distances are used in every possible way satellite links.
However, the satellites have a major drawback. Due to the large distance from the satellite and the limited speed of radio waves, there is a significant delay in spoken responses. So many calls only use the satellite in one direction of transmission (eg New York to Madrid) and a terrestrial microwave link or coaxial cable in the other direction. A satellite link for both directions would be irritating for two people chatting between New York and Hong Kong, and that could only make breaks, something very common in conversation, and also would be affected by the long delay (more than one second) the response of the other person.
Optical fibers
One of the great advances in communications has been the use of digital signals. In telephony, the signal is digitized to reach the PBX. Communication between telephone exchanges is digital, thus reducing noise and distortion and improving the quality and capacity.
Coaxial cables are being replaced gradually by glass optical fibers. Messages are digitally encoded in light pulses that are transmitted over long distances. A fiber cable can be up to 50 fiber pairs, each pair supports up to 4,000 voice circuits. The foundation of the new optical fiber technology is the laser that uses the visible region of electromagnetic spectrum where the frequencies are thousands of times higher than those of radio and therefore can carry a much larger volume of information. The light emitting diode (LED), a simpler device, also used as appropriate for most of the functions of transmission.
A fiber optic cable, TAT 8, carries more than double the existing transatlantic circuits in the 1980s. As part of a system that extends from New Jersey to England and France, can transmit up to 50,000 conversations at once. Such cables also serve as channels for high-speed transmission of computer data, to be safer than that provided by communications satellites (see satellite communications). Other important developments in telecommunications, TAT 9, a fiber cable with greater capacity, became operational in 1992 and can transmit 75,000 simultaneous calls.
Most major cities are now linked by a combination of microwave links, coaxial cable, fiber optics and satellites. The capacity of each of the systems depends on their age and territory covered (the undersea cables are designed in a very conservative and have less capacity than the cable surface), but in general, can be classified as follows: simple scanning through a couple dozen parallel circuits provides pair, the coaxial circuit allow hundreds and thousands per pair cable, satellite and microwave circuits are thousands of links, and fiber optics allows up to tens of thousands fiber circuit. The capacity of each type of system has increased significantly since its inception due to the continuous improvement of engineering.
Radiotelephones
Today, it is possible to receive phone calls even while driving a car. In certain areas there is a radio system connected to the network automatically. Dialing a special code and then the desired number, you may contact a person who is in motion.
Indeed, the radio links are possible for over 55 years. Radio waves in the high frequency band (4-30MHz) are already used in international communications. With the development and improvement of submarine cables and satellites, have come to use in high frequency radio links.
Telephony and broadcasting
Teams of long distance telephony can also be used to transport radio and television to spread great distances between stations to broadcast simultaneously. In some cases, the audio portion of television programs can be transmitted through cable circuits or audio frequency carrier frequencies used to transmit telephone conversations. Television pictures are transmitted via coaxial cable, microwave and satellite circuits.
Videophone
The first two-way videophone was introduced in 1930 by the American inventor Herbert Eugene Ives in New York. The videophone can be connected to a computer to view reports, charts and diagrams in remote locations. Likewise allows face to face meetings of people in different cities and can act as a liaison between meeting centers within a network of cities. The videophones are already commercially available and can be used on domestic lines for callers face to face. Similar functions also exist in the computer or computers connected to the telephone network and equipped for that purpose.
Voicemail
Voicemail allows you to record the received messages for later playback when the call is not heeded. In more advanced versions of voice mail, the user can record a message to be broadcast later during the day.
Voice mail is available in the telephone company as a service switching or by purchasing an answering machine. In general, ordinary telephone equipment is equipped with recording functions, playback and automatic detection of call. If the incoming call is answered on any telephone line rings before a certain number of times, the answering machine does not work. However, the number of calls completed, the answering machine pick up and proceeds to play back a previously recorded message informing the subscriber can not answer the call at that time and invited to leave a recorded message.
The owner of the answering machine is notified of the presence of recorded messages through a light or an audible beep and can retrieve the message later. Most answering machines and operator services all likewise allow the user to retrieve the recorded messages from a remote location by dialing a particular code when they have received response from your computer.
Mobile or cellular
The cell phones are essentially a low-power radios (see Radio mobile phone). The calls go through radio transmitters placed within small geographic units called cells. The cells cover almost the entire territory, but particularly residential areas and communication routes (such as roads and railways) from where you do most of the calls. Radio transmitters are connected to the telephone network, allowing communication with regular phones or to each other.
Adjacent cells operating at different frequencies to avoid interference pear. Since each cell signals are too weak to interfere with those of other cells operating in the same frequencies, you can use a larger number of channels in the transmission with high power radio frequency. When a user moves from one cell to another, the transmission has to change its transmitter and frequency. This change must take place at high speed for a user traveling in a moving car or train can continue their conversation without interruption.
Frequency Modulation Narrowband is the most common method of transmission and each message is assigned an exclusive carrier for the cell from transmitting. Today it multiband mobile phones that can use two or three carriers at once, thus reducing the chance that the phone loses the signal.
The digital mobile phones can be used anywhere in the world using the same mobile telephone system. There are also mobile phones that allow access to the Internet, fax transmission and reception, and even videophone.
Technology Trend
The replacement of coaxial cables for transoceanic optical fiber cable continues today. Advances in integrated circuit technology and semiconductor designing and marketing have enabled phones and switching centers that not only produce high-quality voice fidelity, but offer a range of functions such as stored numbers, call forwarding, call multiuser, call waiting and caller ID number.
Traditionally, the phone has been used to transmit voice, however, is increasingly being used more for other types of transmissions. You can transmit images by telephone using the fax. Two computers can communicate with each other by telephone using the modem. This type of communication is becoming popular because it allows access to the Internet using just a modem connected to the telephone line.
There have been many great technological inventions over the years. While every invention has it own importance some of these inventions have revolutionized our lives. Few inventions which revolutionized our day to day lives are
1. Radio:- Our only source of information was newspapers and that was never live. We used to get information of a particulars days happenings atleast a day later through our newspapers. Radio has given us the option of live broadcasts. We used to know of scores and player performances in cricketing events and Davis Cup through commentary. The excitement of hearing something happening in real time was a altogether different experience.
2. Transistor:- Transistor is an extension of Radio. Transistors released us from being confined to our homes to listen to a radio commentary. Wireless transistors meant we can listen to live commentary almost anywhere at office of while walking on the road. Transistors were easy to carry and that was an additional advantage over a radio.
3. Television:- Another modified version of Radio is Television. With Television we were able to see whom we have only heard of in the past. Sunil Gavaskar was a household name having broken almost every possible record during his time, but one never knew how Sunil Gavaskar looked like. Television gave us a chance to see how our heroes as to how they actually looked. Television also taught us how to play a game. For example before the advent of television cricket was also about batsman making contact with the ball and bowlers hitting the stumps. Television taught us that cricket means lots of classical strokes, fast bowlers bouncing out batsman or spinners weaving their magic with classical deliveries with lovely action.
4. Video Cassettes:- Earlier people used to go to theatres to watch movie. A person has to adjust his timings to suit the timings of the movie shown in a theatre. An added inconvenience is standing in queues. There was also a probability of wasting ones time and energy and coming back without seeing the movie due to tickets being sold out. With advent of Video Cassettes you need not go to theatres, on the contrary theatres come home. You are your own boss, you decide your timings and can see the movie with any number of people without paying anything extra. You can pause, rewind or forward whenever you want to.
5. Video Recording:- Earlier a person had the option of watching a movie 20 years later if there was a repeat show in theatres. Now a person can see happenings in his own life as and when he wants. A person can see his engagement or marriage videos whenever he wants to. It is really a thrill for a person to see how he looked 20 years back. It is also nice to show it to his kids. The kinds also have the option of seeing how their parents looked 20 years back.
6.Telephone Land line:- With the advent of land line telephones, distance ceased to be a factor and our relatives were only a call away even though they used to stay thousands of miles apart. The time devoted to writing letters, usage of words, writing and re writing words, waiting for the letter the reach the recipient and then waiting for the recipients to reply and receive the letter is all gone. Telephones also gave the option of being our natural self while speaking because a letter can never convey what you actually want to speak.
7. Pager:- Not many people remember a pager these days, because it did not last long as mobiles can soon afterwards. Pager was some sort of a mini handset. The size of a page is almost one fourth of a todays sleek mobile handsets. Even when you are on the move, a person can flash a message to you which will reach you on your pager. Once the person receives the message, depending on the urgency he can go to a telephone booth and interact with the person who sent the message.
8. Mobile:- Mobile is advanced version of landline and page and perhaps one of the most remarkable invention. Wherever you are does not matter, you can always make or receive calls from anywhere to anywhere
9. Email: Advent of email gave a option a person who could never even dream of. Sending messages from anywhere to anybody and receiving message from anybody and from anywhere. With telephone a person had to curtail the duration of his conversation especially when talking abroad because costs are higher if the duration is life. With email you can be yourself, write plenty without worrying about the cost.
10. Search Engines:- You can access the world sitting from the comfort of your home, office or internet parlous whichever part of the world you are. You can get information on a particular product or contact details of a organization within a few seconds. You can access data from millions of miles away sitting from the comfort of your desk.
There have been far too many inventions in the world which revolutionized our lives, and therefore difficult to mention all of them. However the above mentioned 10 inventions have been the most significant.
Regards
Satish
It was a serene evening with a stunning sunset that inspired me ending up with the most melodic composition of my life. The cozy sundown and the emotive symphony reminded me my academic chums and I wished to transmit the masterpiece and dedicate it to them. Though I don’t own a radio station but my desperation took me to the new planet called internet as people have increased reliance on the web world for a whole range of activities — accessing everything from medical information to political news to driving directions, to shopping, to pay bills, to book tickets, to enjoy music, to watch videos, to attend lectures and so on. I too thought to find a river to get my creative juices floated away and started googling. I know if the words googling or blogging had been used 10 years ago, people might have started scratching their heads. But now technology has altered the pace of popular culture and added plenty of new words to our lexicon, although some have yet to make the dictionary.
At times it seems far-fetched that a single clack can bring people to an amazing virtual globe where every hit on the browser opens a new avenue.The web world has radically groomed the way commerce is conducted and transacted. Right from online retailing and marketing to blogging and broadcasting, I found there is a huge empty space for good brains to try hands in the global economy of online world.
According to the latest statistic I encountered with while googling, there are around 694 million netizens worldwide. India also appears to have embraced the bandwagon with a degree of ambivalence and tremendous enthusiasm towards this magical phenomenon. It is revealed that approximately 40 million Indians access internet regularly and that is jump of 700% in last six years.
This extensive and diversified use of technology and the busy schedules of lives lead most of Internet population to either shop or research for the products and services online. And to grab this whole new breed of potential customers, Online Retailing came in to picture which lead businessmen to make their presence felt on the web. Though earlier it was a hard nut to crack but today thousands of tools are available using which a local, small-town business with a very basic knowledge of computers can go global on WWW and get accessible anywhere in the world.
Following the trend of online retailing, Internet Marketing and Advertising are too on the go to boom up the industry. The various technical tools of traffic generation like Search engine optimization, Pay per click adds, Link building, Link exchanging, Email marketing, Google adsense and Google adwords hit the online economy incredibly well and opened the new doors of income for the netizens. While on my tour to this second world I got to see some statistics revealing that Revenue figures for Internet advertising registered a 35% increase from those of 2005. Online-ad revenue generated from search-engine advertising was 40%, while display advertising, including banners and media ads, generated 32% of total revenue. This tremendous growth of interactive advertising is supported by advertisers and agencies that have started to be acquainted with internet as a medium that can influence consumer behavior. Even the big chunks like Reliance, ICICI, and Vodafone etc built up their apartments inthe web world to captivate the net inhabitants.
It was even more startling to see that Blogging and Review Writing which were earlier used to depict creative thoughts and truth could not remain impervious from the radical era of internet marketing and advertising. Now people use them to increase their customer base. But positively it’s also escalating pocket weights for bloggers and writers.
Adding impetus to the emerging opportunities on internet, I was on cloud 9 to see that Online Broadcasting has become quite a revolution in the world of media, permitting anyone from anywhere to transmit his/her own programs, from independent music to news. Both Internet radio and podcasting use the World Wide Web to distribute media to subscribers. In the case of Internet radio, one can simply listen to the media being streamed across the web world. Podcasting, on the other hand, lets people download the files onto a portable playback device such as an iPod. At the end of this virtual journey I finally got a road to route up my music and much more to share with my chums and other netizens.
It is the internet’s abundance and miscellany of information easily found and conveniently shared, that make it such an integral part of modern life, reshaping people’s informational, social and economical universes. Thanks to Tim Berners-Lee who, way back in mid 19s introduced this astonishingly amusing world called www with which we have come a long a ways but still have a ways to go!
- Sadiya Naseem
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