Telegraphic communication is used to transmit information via wires, radio links and other communication channels. Since ancient times, people have tried to transmit information from a distance. Wrecked sailors made bonfires. Warriors who saw the enemy on the borders of their lands, informed the commanders about this with smoke from the fire. During the disaster, different nations beat tambourines and drums to report danger. The development of the telegraph began in the 18th century.
Optical telegraph
The first optical telegraph transmitted information using light. The inventor of the telegraph apparatus was a mechanic from France, Claude Chappe in 1792. Two years later, the telegraph gained popularity in Europe, began the active construction of communication lines. Napoleon is believed to have won a number of victories thanks to a new invention. The transfer of orders between major cities was 10 minutes.
The first telegraph consisted of three slats that occupied a certain position. There were 196 such signs in total. They denoted letters, punctuation marks and some words. Recipients used a spyglass. The system allowed transmitting 2 words per minute over significant distances.
Schapp's pupil invented an optical device. The main difference is the ability to work at night. The slats occupied 8 different positions, in which not only letters, words, but also individual phrases were encoded. The coding system has undergone changes, reference books for decoding signals were published. The speed of information transfer has increased.
The optical telegraph had several advantages over other means of communication used earlier:
- signal accuracy;
- lack of fuel;
- information transfer rate.
The system had disadvantages:
- dependence on weather conditions;
- building points every 30 km;
- the availability of operators.
In 1824, the first telegraph line between Petersburg and Shlisselburg was built in Russia. Used to transmit information on shipping on the Neva River. In 1833, the second line was opened. In 1839, the last line of an optical telegraph in Russia with a length of 1,200 km appeared, which made it the longest in the world. The signal transmission from Petersburg to Warsaw was no more than half an hour.
The telegraph was useful, but it was not profitable to use optical telegraph communication for commercial purposes. This continued until an electrical apparatus was invented.
Telegraph of Semmering
The optical telegraph allowed the transmission of information throughout Europe, but between the continents they used maritime mail. Scientists struggled to create an electric telegraph. The first sample of such an invention was presented in 1809 by the scientist Samuel Thomas Semmering. He noticed that when electric current passed through the electrolyte, gas bubbles were released. The current could decompose water into oxygen and hydrogen. This formed the basis of the telegraph, which was called electrochemical.
The electric telegraph had wires hooked to each letter of the alphabet. Before sending a message, an alarm was triggered on the receiving side. After the operator was ready to receive the signal, the sender in a special way disconnected the wires so that the current passed through all the letters that were present in the telegram.
Later, this unit simplified Schweiger, reducing the number of wires to two. He changed the current duration for each letter. It was difficult to work with an electrochemical apparatus. Sending and receiving characters was slow, and observing the gas bubbles was tedious. The invention has not received widespread use.
In 1820, Schweiger invented a galvanoscope, thanks to which the interaction of current and magnetic fields was studied. In 1833, a galvanometer was designed by the scientist Nervander. Based on the deflection of the arrow, the current was estimated. These inventions formed the basis of the electromagnetic telegraph. The signal changed depending on the current strength.
Electromagnetic apparatus
The first device for transmitting data, based on the action of electromagnetic fields, was created by the Russian baron Pavel L. Schilling. He demonstrated the telegraph at a meeting of testers in 1835. The device for transmitting data consisted of a keyboard closing the circuit. Each letter of the alphabet has a special key combination. Before sending a message, an alarm went off on the receiving side.
The device consisted of 7 wires, 6 of which were used for the signal. One wire was required to call the operator. The earth served as the return conductor. The device itself was bulky and was not used massively.
The telegraph of Schilling became interested in the English inventor William Cook. Two years later, the device was improved, but did not become widely used. The operator needed to pick up the oscillation of the galvanometer by eye, which led to errors and rapid fatigue. It was also impossible to have time to record the information received, so there was no question of the reliability of the speech.
The longest line with an electromagnetic telegraph was built in Munich and was 5 km long. The scientist Steingel conducted experiments and found out that a return wire is not required for data transfer. It is enough to ground the cable. The positive pole of the battery was grounded at one station, and the negative at the other.
For some time, the electromagnetic apparatus was used to transmit messages over long distances. But for the development of telegraph communication, a device was needed that could record the information received. The inventors of the whole world continued to work on this.
Telegraph morse
Artist Samuel Morse was the first inventor to create a telegraph based on Morse code. During a trip to America, he became acquainted with electromagnetism. The device for transmitting data over a distance interested the artist, he had the idea to create an apparatus that would record data on paper.
The invention was released a few years later. Despite the fact that the project immediately arose in the head of Samuel Morse, the telegraph could not be quickly created. In England there were no electrical appliances, the necessary parts had to be taken from afar or created by ourselves. Morse had companions who helped in the collection of the telegraph.
As planned by Samuel, the new telegraph apparatus was to transmit information in the form of dots and dashes. Morse code was already known to the world. The very first disappointment befell the inventor during the creation of insulated wire. Magnetization was insufficient; the experiment had to be continued. Studying the literature of famous scientists, Morse corrected errors and achieved first successes. The device swung the pendulum under the influence of electromagnetic current. An attached pencil drew the given signs on paper.
For telegraph communication, Samuel's achievement was a huge breakthrough. During the experiment, it turned out that the electromagnetic field is short enough, which means that the device is useless for transmitting information between cities. Morse developed an electromagnetic relay that responded to minor deviations in the current flowing through the wires. At each symbol, a relay was closed, and current was supplied to the writing device.
The completion of work on the main parts of the device occurred in 1837. But the government was not interested in the new development. It took Morse more than 6 years to receive funding for a 64-km telegraph line. At the same time, difficulties reappeared. It turned out that dampness has a detrimental effect on the wires. The line began to lead above the ground. In 1844, the world's first telegram was sent using the Morse code.
After 4 years, telegraph poles appeared in many states of the United States, and then in other countries.
Morse Telegraph Writer
Morse telegraph received universal popularity due to its simplicity. The main part of the apparatus was a telegraph key, and the receiving side had a writing device. The key consisted of a metal lever that rotated around an axis. Upon receipt of the telegram, he closed in such a way that the current flowed to the writing device. The operator who sent the telegram closed the telegraph key. Pressed once - there was a short signal, held for a long time - the signal came long.
The recorder converted signals in the form of dots and dashes. Morse code became popular, but only professionals familiar with the Morse code could convert the cipher. To eliminate this drawback, scientists began to develop telegraphs that can convert information into letters.
Based on the Morse telegraph in 1855, the inventor Hughes created an apparatus that had 28 keys and could print 52 letters and characters.
Telegraph Development
The first apparatus, capable of writing letters, was set in motion by a weight of 60 kg. Electric current instantly reached the receiving side, where the device lifted the paper moving at a constant speed to the desired letter. Thus, a message was printed on paper. Despite some difficulties, messages were sent and received quickly. It was easy to train operators.
The first telegraph line between Petersburg and Warsaw did not last long. The optical telegraph was uncomfortable, slow and expensive. In 1852, the first telegraph line between Moscow and St. Petersburg was built on the basis of electromagnets in Russia. In 1854, the optical line ceased to exist.
After the advent of the Morse device, telegraph communication began to actively develop. The first devices could only transmit or receive a signal, then these actions occurred simultaneously. Such a data processing scheme was proposed by the Russian inventor Slonimsky. The signals did not mix, but two conditions had to be observed: the devices should always be in touch and not affect each other during transmission.
In 1872, in France, Jean Maurice Bodot created a telegraph that is able to simultaneously send and receive several messages. The speed of sending information has increased significantly. At the same time, the device worked on the basis of the telegraph Hughes, who sent and received messages bypassing the Morse code. Two years later, the device was improved. Its throughput was 360 characters per minute. A little later, the speed increased by another 2.5 times. The massive use of the telegraph of Bodot in France began in 1877. Bodo also created a telegraph code, which later became known as the International Telegraph Code No. 1.
At the same time, the first underwater lines were laid. So, there was a telegraph connection between France and England, England and Holland and other countries. In 1855, the first submarine cable was laid between England and the USA, but in 1858 the cable broke. Restored it a few years later.
The development of telegraph communication continued rapidly. News between continents and countries was broadcast within hours or minutes. In 1930, a telegraph with a disk dialer was invented. Thus, it was possible to quickly identify the recipient and speed up the process of connecting with him. At the same time, the first TELEXS telegraph operators appeared in England and Germany.
Since the 50s of the XX century, not only letters, but also pictures began to be transmitted by telegraph. In fact, these were the first faxes. Photo telegraphs were especially popular with journalists. News from other countries and photographs were broadcast quickly and were immediately printed in newspapers. Moreover, in addition to the telegraph, telephone and facsimile communications developed.
Most of the development was carried out to transmit information in Latin. In 1963, a new telegraph code was invented in the USSR, which included the letters of the Russian alphabet, Latin letters and numbers. But at the same time, the Russian letters E, Ch and Kommersant were not involved. Instead, they wrote the number 4. Such a code was used on the first mobile phones in Russia.
With the development of facsimile in the 80s, the telegraph began to lose ground. Despite the fact that the communication brought together more than 100 countries, the opportunity to send not only a short message, but also other information interested people. Convenient fax machines have changed the life of the telegraph.
In the XXI century, some countries completely abandoned telegraph communications. In 2004, the telegraph ceased to exist in the Netherlands, a little later - in the United States, in 2013 India abandoned it. In Russia, telegraph communication still exists. This is due to the remoteness of some regions and the large area of the country. The Internet and other means of transmitting information appeared thanks to the telegraph and destroyed it.
Wireless telegraph
The founder of the wireless telegraph was the Russian scientist Alexander Stepanovich Popov. It was first presented at a meeting of the physico-chemical society. The device could transmit information based on radio waves. Two years later, the wireless device was tested in real conditions. The first radio telegram was sent from the coast to a sea ship. A little later, the device was improved and transmitted signals using the Morse code. Thus, communication via telegraph became available not only on land, but also on water. Radio waves underlie radio and telephone communications.
The first test of the serious conditions of a wireless telegraph took place at a naval base. The sea ship General Admiral Apraksin off the coast of the Gulf of Finland ran aground. Thanks to radio communications, information was received at headquarters. Under the guidance of A.S. Popov, a rescue operation took place. The scientist was responsible for the operability of communication. The icebreaker Ermak was able to free the ship, which spent almost 4 months on the ice. Demoman and the captain of the icebreaker had a constant relationship, so the operation was successful. The escaped ship participated in military battles in 1904-1905.
The founder of radio communications in Russia is A.S. Popov, at the same time the Englishman Marconi created a radio and received a patent for it. It is worth noting that his device was very similar to the invention of Popov, a description of which was published several times in well-known magazines.
Principle of operation
Telegraph messages are transmitted at a specific speed. Baud was taken as the unit of telegraphy speed. It determines the number of telegraph parcels transmitted per 1 s.
The principle of telegraph communication is based on the action of an electromagnet through which current flows. The energy of the electric field is converted into mechanical. The current flows through the winding, a magnetic field appears, which attracts the armature. The core, connecting with the anchor rotates around its axis. If no current flows, the magnetic field disappears, and the armature returns to its original position.
A line relay can be used to increase the reliability of the device. In this case, he reacts to the slightest fluctuation. For the transmission of code information, direct or alternating current can be used. If the current is constant, then the package can be transmitted in a single or bipolar manner. When one direction appears in the streamline, they talk about unipolar data transmission.
If during the transmission of a message there is a supply of current in one direction, and during a pause - in the other, then the bipolar method works. The synchronous method works under the condition of simultaneous transmission and receipt of information.
The start-stop method has three types of sending - the information itself, start and stop. Transmission is carried out in cycles that begin after the start signal is given and ends when the stop signal appears.
Direct current is not used over long distances. To increase the distance, the current strength is made larger or pulse transmission is connected. But these methods have disadvantages. It is not always possible to increase the current strength due to technical delays. And impulse transmission can distort information.
The most widely used frequency cabling. Alternating current allows you to send information without a range limit. The number of telegrams transmitted simultaneously increases.
The telegraph communication range is understood to mean the maximum distance at which information is not distorted and an intermediate station is not required. A telegraph is used to transfer messages between different subscribers. Transfer can be carried out through the operator or independently, if the subscriber is included in telegraph communication.
Benefits
After the advent of the telegraph and mass popularity, only the positive aspects of communication were visible to ordinary inhabitants. , . , .
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disadvantages
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- Delivery to the addressee is carried out by mail workers, this increases the time of receipt of the message.
- Information cannot be sent to countries where the telegraph has been liquidated.
Telegraph communication is losing its former meaning. With the advent of the Internet, personal computers, smartphones, there are many other ways to send a message. The telegraph is losing its relevance.