Origin of the word;
The word telephone is a combination of the Ancient Greek Telos “Far” and “Phone” words. It passed into Turkish from the French telephone. Linguist Nurullah Ataç coined the word “distant speaks” as its Turkish equivalent to the word “telephone”. This word was asked to be translated into Turkish, but the word telephone was used again because the public did not use this word.
The first telephone device to transmit conversations openly was the device called radiophone developed by Alexander Graham Bell and Charles Sumner Tainter. Two scientists made the first successful experiment with this device on February 15, 1880. The transmitter was placed on top of Franklin School on 13th Street in Washington. Tainter took the handset to speak: Mr. Bell … Mr. Bell … If you can hear me, please come to the window and shake your hat. Soon Bell came to the window of his laboratory on 14th Avenue. He was wearing a hat. He paused for a moment, then started waving his hat.
The telephone was first used to talk over two connections similar to the telegraph system. Most of the time, one connection was iron wire and the other connection was ground, so the loss was high and the sounds were heard mixed. With the development of copper alloys, the number of wires has been increased. As the number of speeches increased, the connections started to not catch up. In 1886, a device (multiplex) that sends sound with different frequencies from a single circuit was short-circuit. Losses were eliminated with risers placed on long lines. One of the biggest steps on the phone is automatic conversations without using an operator. With the Strowger automatic dialer developed in 1891, subscribers were able to connect to each other without an operator intervening. This mechanism was developed in 1920 as the Bell mechanism. On October 18, 1892, the first long telephone line was opened between Chicago and New York. After 1948, with the emergence of the transistor device, electromagnetic relay systems left their place to electronic circuits. The electronic seeker system was first put into service in the USA in 1965.
Another big step taken on the telephone is the use of high frequency radio broadcasts in long distance conversations. Relay stations, located at intervals of 150–300 km, transmit conversations over coax cables and airborne electromagnetic broadcasts. As the frequency increases, the number of channels for speech over a single connection increases. With such a system, it is possible to make 3600 conversations between two relay stations at the same time.
This development was followed by speeches made through satellites.
Telephone conversations between the mainland started in 1915. The first speech was made between Paris and Arlingon in the USA. Powerful radio transceivers were used for inter-mainland phone calls. Since the effect of the ionosphere makes speech difficult, underwater cables have been used. The first underwater cable phone calls were made in 1950 at a distance of 185 km between Florida and Havana. Because the result was satisfying, the same mechanism was established between New York and London in 1956.
The first inter-mainland telephone conversations via satellite began in 1960. Telstar I, Telstar 2 and other satellites followed when a telephone connection was established between the Echo 1 satellite and the west coast of the USA. Today, with the activation of satellites, automatic phone calls can be made with ships or planes. One of the satellites put into orbit by the space shuttle Discovery in 1985 allows 20,000 speeches at the same time.
The events that occur during a telephone conversation over an electrical circuit can be listed as follows:
Sound energy is transformed into mechanical energy.
Mechanical energy turns into electrical energy.
Electrical energy is transmitted.
On the opposite side, electrical energy is transformed into magnetic energy.
Magnetic energy is transformed into mechanical energy.
Mechanical energy turns into sound energy.
Since the propagation velocity of electrical vibrations in conductors is several hundred thousand times higher than the propagation speed of actual vibrations in air (in the range of 200,000-300,000 km / h), telephone conversations feel that they are facing each other, despite the distance. The telephone system performs three main functions. It provides speech communication between two subscribers and generates calling, busy dialing, and voice signals between subscribers. In non-automatic magneto phones, these operations are done manually.
“The main parts of a telephone appliance are”
Sound receiver (microphone),
Microphone current source,
Sound transmitter (headphone),
Calling and invocation patterns,
Telephone devices connected to manual and automatic exchanges are different from each other. Each contains some of the above parts. The handset of the telephone converts sound into electrical energy and electrical energy into sound. The automatic telephone device has a switch that opens the circuit when the handset is lifted and a numerator on the front. When the telephone receiver is lifted, an electrical circuit is established between the telephone and the power plant. Tone is heard from the handset. For example, dialing the number 6 from the numerator will open and close the electrical circuit six times. The openings and closings in the electrical circuit are counted as signals in the power plant through the circuits.
The communication does not have to be in the form of speech. The computers installed in the local switchboards make selection according to the type of signal sent and deliver the distribution to the terminals in the form of analog telephone, digital telephone, facsimile, telex, and television data processing. Thus, in addition to telephone conversations, television, facsimile painting and writing, telex and computer operations are also carried out very quickly and with high quality.
“Communication lines: Communication (communication) possibilities are very diverse. These”
Two-wire speech circuits are not used outside of the urban distribution system because the losses are very high at long distances and the number of channels is limited. Communication systems have improved a lot in terms of capacity and quality by using radio broadcasts. Telephone conversations can be made both directly as an analog signal and by broadcasting after this analog signal is converted into a digital signal. Because of the echo problem and the high signal noise level, the analog signal was abandoned and the digital signal system was adopted. In digital signal systems, the analog signal is divided into slices and divided into smooth pulses. These pulses are then encoded and sent from the transmitter antenna as ‘0’, ‘1’ digital broadcast. Since the encoding process can be done separately for each speech, thousands of speeches can be broadcast simultaneously from an antenna as pulses. The receiving phone reaches the subscribers by decoding these thousands of broadcasts received from the station in the decoder, converting them into audio signals and passing through the central logic circuit. Coded pulses can be sent from the antenna as well as from coaxial cables. Losses in coaxial cables are much reduced. Instead of coaxial cable, faster high-capacity optical fiber cables with very low loss rate can be used. The digital signals encoded in the optical fiber system are converted into optical signals and sent. In the opposite station, optical signals are first converted to electronic signals and then to an audio analog signal and transmitted to the subscribers through the local central logic circuit.
A conversation is made at the same time in a two-wire communication system. However, there are 30 channels in the digital radio link communication system with pulse code modules. Coax cable digital radio link communication system, on the other hand, has the capacity to send 30 megabits of information per second and has 1920 channels. Such a system, which was put into service in F. Germany in 1985, has a capacity of 565 mbit per second, In other words, 7680 is available for speech or information transfer at the same time. Fiberoptic systems operate at a capacity of 140 mbit / second and above. Fiberoptic communication system is the most perfect of the existing systems with its capacity height, ease of installation, maintenance-free, high quality information. In summary, the names of telephone exchanges are as follows: Electromechanical telephone exchange, electronic telephone exchange, automatic telephone exchange, long distance telephone exchange, transit telephone exchange, semi-electronic telephone exchange, semi-automatic telephone exchange, local (local) telephone exchange.
The biggest benefit of the telephone in practice is that the communication is done quickly. Telephone calls made by reflecting from satellites via fiber optic, coaxial cable and electromagnetic means have connected every corner of the world. Channel capacities of telephone systems are increasing day by day. Increases in the number of channels make the phone even more practical. One of the important developments in telecommunications is the emergence of wireless telephony. By connecting shortwave radio transmitters to the normal telephone system, the possibility of speaking on the phone has emerged. With this system, as there is uninterrupted connection between regions (www), even those who travel very long-range can instantly call the desired location.