Telegraph communication is used to transmit information via wires, radio lines and other communication channels. Since ancient times, people have tried to transmit information at a distance. The shipwrecked sailors kindled fires. The warriors, who saw the enemy on the borders of their lands, notified the commanders about this with smoke from the fire. During times of trouble, different peoples beat tambourines and drums to signal 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 machine was French mechanic Claude Chappe in 1792. Two years later, the telegraph gained popularity in Europe, and active construction of communication lines began. It is believed that Napoleon won a number of victories thanks to a new invention. Transmission of orders between major cities took 10 minutes.
The first telegraph consisted of three slats that occupiedcertain position. There were 196 such signs in total. They denoted letters, punctuation marks and some words. The receivers of the signal used a spyglass. The system made it possible to transmit 2 words per minute over considerable distances.
Chappe's student improved an optical device. The main difference is the ability to work at night. Planks occupied 8 different positions, in which they encoded not only letters, words, but also individual phrases. The coding system has undergone changes, reference books for decoding signals have been published. The speed of information transfer has increased.
The optical telegraph had a number of advantages over other means of communication used earlier:
- signal accuracy;
- lack of fuel;
- data transfer rate.
The system was flawed:
- depending on weather conditions;
- plotting points every 30 km;
- presence of operators.
In 1824, the first telegraph line was built in Russia between St. Petersburg and Shlisselburg. Used to transmit information about navigation on the Neva River. In 1833 a second line was opened. In 1839, the last 1200 km optical telegraph line appeared in Russia, making it the longest in the world. The signal transmission from St. Petersburg to Warsaw took 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 the inventionelectrical apparatus.
Semmering Telegraph
Optical telegraph made it possible to transmit information across Europe, but sea mail was used between continents. Scientists fought over the creation of an electric telegraph. The first example of such an invention was presented in 1809 by the scientist Samuel Thomas Semmering. He noticed that when an 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 attached to each letter of the alphabet. Before the start of sending the message, the alarm clock on the receiving side went off. After the operator was ready to receive the signal, the sender disconnected the wires in a special way so that the current passed through all the letters that were present in the telegram.
Later Schweiger simplified this device by reducing the number of wires to two. He changed the duration of the current for each letter. It was difficult to work with the electrochemical apparatus. Sending and receiving characters was slow, and watching the gas bubbles was tedious. The invention was not widely used.
In 1820, Schweiger invented the galvanoscope, thanks to which the interaction of current and magnetic fields was studied. In 1833, the galvanometer was designed by the scientist Nerwander. Based on the deflection of the pointer, the current strength was estimated. These inventions formed the basis of the electromagnetic telegraph. The signal changed dependingfrom current strength.
Electromagnetic apparatus
The first apparatus for data transmission based on the action of electromagnetic fields was created by the Russian Baron Pavel Lvovich Schilling. He demonstrated the telegraph at a meeting of testers in 1835. The device for data transmission consisted of a keyboard that closed the circuit. Each letter of the alphabet was associated with a special key combination. An alarm was triggered on the receiving side before the message was sent.
The device consisted of 7 wires, 6 of which were used for the signal. One wire was required to call the operator. Earth served as the return conductor. The apparatus itself was bulky and was not widely used.
Schilling's telegraph 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 catch the oscillation of the galvanometer by eye, which led to errors and rapid fatigue. It was also impossible to have time to write down the information received, so there was no question of reliability.
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 transmission. It is enough to ground the cable. At one station, the positive pole of the battery was grounded, and at the other, the negative.
For some time, the electromagnetic apparatus was used to transmit messages over long distances. But for the development of telegraph communications, a device was required that could record the information received. Continued to work on thisinventors around the world.
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 artist was interested in a device for transmitting data over a distance, he had the idea to create a device that would record data on paper.
The invention saw the light of day 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 spare parts had to be transported from afar or created by yourself. Morse had associates who helped collect the telegraph.
According to Samuel's plan, the new telegraph machine was supposed 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. The magnetization was insufficient, so the experiment had to be continued. Studying the literature of famous scientists, Morse corrected the mistakes and achieved the first successes. The device under the influence of electromagnetic current swung the pendulum. The tied pencil drew the given characters on the paper.
For telegraph communications, Samuel's achievement was a huge breakthrough. During the experiment, it turned out that the electromagnetic field is enough for short distances, which means that the device is useless for transmitting information between cities. Morse developed an electromagnetic relay that responded to slight deviations in the current flowing through the wires. With each character, the relay was closed, and current was supplied to the writing instrument.
The main parts of the instrument were completed in 1837. But the government was not interested in the new development. It took Morse more than 6 years to get funding for a 64 km telegraph line. At the same time, difficulties arose again. 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 using Morse code was sent.
After 4 years, telegraph poles appeared in many US states, and then in other countries.
Morse telegraph writing instrument
The Morse telegraph gained general popularity due to its simplicity. The main part of the apparatus was a telegraph key, and the receiving party had a writing instrument. The key consisted of a metal lever that rotated around an axis. When a telegram arrived, it closed in such a way that the current went to the writing instrument. 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 writing instrument converted the signals into dots and dashes. Morse code became popular, but only professionals familiar with Morse code could convert the cipher. To eliminate this shortcoming, scientists began to develop telegraphs capable of converting 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 symbols.
Development of the telegraph
The first machine capable of writing letters was powered by a 60 kg weight. The 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. Operator training was easy.
The first telegraph line between St. Petersburg and Warsaw did not last long. The optical telegraph was inconvenient, slow and expensive. In 1852, the first telegraph line between Moscow and St. Petersburg was built in Russia on the basis of electromagnets. In 1854, the optical line ceased to exist.
After the advent of the Morse device, telegraph communications began to develop rapidly. 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 were not mixed, but two conditions were required: the devices must always be in touch and not affect each other during transmission.
In 1872 in France, Jean Maurice Baudot creates a telegraph that can simultaneously send and receive multiple messages. The speed of sending information has increased significantly. At the same time, the device worked on the basis of the Hughes telegraph, which 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 speedincreased by 2.5 times. The widespread use of the Baudot telegraph in France began in 1877. Bodo also created a telegraph code, which later became known as International Telegraph Code No. 1.
At the same time, the first submarine 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 United States, but in 1858 the cable broke. It was restored after a few years.
The development of telegraph communications continued rapidly. News between continents and countries was transmitted within hours or minutes. In 1930, the rotary telegraph 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. Phototelegraphs were especially popular with journalists. News from other countries and photographs were transmitted quickly and immediately printed in newspapers. At the same time, in addition to the telegraph, telephone and facsimile communications developed.
Most of the development was carried out to transmit information in Latin. In 1963, the USSR came up with a new telegraph code, which included the letters of the Russian alphabet, Latin and numbers. But at the same time, the Russian letters E, Ch and Ъ were not involved. Instead of H, they wrote the number 4. This code was used on the first mobile phones inRussia.
With the development of facsimile communication in the 80s, the telegraph began to lose ground. Despite the fact that the connection united more than 100 countries of the world, 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 21st 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. Telegraph communication still exists in Russia. This is due to the remoteness of some regions and the large area of the country. The Internet and other means of information transmission 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 radiotelegram was sent from the shore to a sea ship. A little later, the device was improved and transmitted signals using Morse code. Thus, communication via telegraph became available not only on land, but also on water. Radio waves are the basis of radio and telephone communications.
The wireless telegraph was first tested under severe conditions at a naval base. The sea ship "General-Admiral Apraksin" ran aground off the coast of the Gulf of Finland. Thanks to radio communicationentered the headquarters. A rescue operation took place under the leadership of A. S. Popov. At the same time, the scientist was responsible for the performance of the connection. The icebreaker Yermak was able to free the ship, which had been on the ice for almost 4 months. The demolition men and the captain of the icebreaker had constant communication, so the operation was a success. The rescued ship took part in military battles in 1904-1905.
A. S. Popov is considered the founder of radio communications in Russia, at the same time the Englishman Marconi created a radio receiver and received a patent for it. It is worth noting that his device was very similar to Popov's invention, the description of which was published several times in well-known magazines.
Working principle
Telegraph communication messages are transmitted at a certain speed. Baud was taken as the unit of telegraphy speed. It determines the number of transmitted telegraph parcels in 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. Current flows through the winding, a magnetic field appears, which attracts the armature. The core, connected to the anchor, rotates around its axis. If there is no current, the magnetic field disappears and the armature returns to its original position.
A line relay can be used to increase the reliability of the machine. In this case, it reacts to the slightest fluctuation. To transmit code information, direct or alternating current can be used. If the current is constant, then the package can be transmitted in a one- or two-pole way. Atthe appearance of one direction in the current line speaks of a unipolar data transmission.
If during the transmission of a message a current is supplied in one direction, and during a pause - in the other direction, then the two-pole 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 - information itself, start and stop. The transmission is carried out in cycles that begin after the "start" signal is given and end when the "stop" signal appears.
Direct current is not used for long distances. To increase the distance, the current strength is increased or a pulsed broadcast is connected. But these methods have drawbacks. It is not always possible to increase the current strength due to technical delays. And impulse transmission can distort information.
Frequency telegraphy has received the greatest application. Alternating current allows you to send information without range restrictions. The number of simultaneously transmitted telegrams is increasing.
Under the telegraph communication range is understood the maximum distance at which information is not distorted and an intermediate station is not required. The telegraph is used to send messages between different subscribers. The transfer can be carried out through the operator or independently if the subscriber is included in the telegraph connection.
Benefits
After the advent of the telegraph and mass popularity, ordinary people could see only the positive aspects of communication. ByCompared with other means of communication, the telegraph has advantages. For these reasons, it is still alive in Russia and is popular in government institutions and in remote regions where Internet access is not possible.
Telegraph feature:
- coordination of police services;
- organization of search activities;
- receiving messages from citizens;
- reception of information at the object of private security;
- transfer of documentary information;
- own communication in public and private enterprises.
The main positive qualities of the telegraph are:
- Documentation of received and sent information.
- High noise immunity.
- Ability to send a certified telegram.
- Reliability and quality of transmission.
- Telegram reaches the addressee.
- Minimum transfer time.
- It is difficult to get into the local telegraph line, therefore it is in demand in government agencies.
- The telegraph machine can record a message or fax without operator assistance.
Flaws
Disadvantages of telegraph communication, which are especially noticeable after the appearance of other means of communication:
- Information may be invalid if the typing operator made mistakes.
- Employees who send or receive telegrams have access to information.
- Delivery to the addressee is carried out by postal workers, this increases the time of receiptmessages.
- You cannot send information to countries where the telegraph has been eliminated.
Telegraph communication is reducing its former importance. With the advent of the Internet, personal computers, smartphones, many other ways to send a message have appeared. The telegraph is losing its relevance.
