This creation revolutionized the world of communications and at the same time the life in general of humanity by accelerating the process of sending and receiving information. That speed is comparable to the speed of its evolution that was so fast that it makes one doubt and wonder Who Invented the Telegraph?
Who Invented the Telegraph?
The creation of the telegraph is associated with a series of discoveries, advances and inventions in the scientific field, attributable to different people, specialists in the most varied activities, who at a relatively fast speed, in recent years, have taken us, from devices optics from the mid-eighteenth century to the most sophisticated communication systems used today.
Primitive means of remote communication
Since its inception, mankind has used various primitive types of signaling and communication for the rapid transmission of important information in cases where, for various reasons, it was not possible to use the means of common use for informational contacts. Fires lit in elevated areas of the terrain, or the smoke from such fires, were supposed to notify the approach of enemies or an impending natural disaster. This method is still used by those who get lost in the taiga or by tourists who experience a natural disaster.
Some tribes and peoples used for these purposes certain combinations of percussion sound signals such as drums and wind musical instruments such as hunting horns, others learned to transmit certain messages by manipulating reflected sunlight through a system of mirrors. In the latter case, the communication system received the name "heliograph", which is a primitive light telegraph.
optical telegraph
In 1778, an optical telegraph to establish communications by means of lights was installed between the Paris and Greenwich observatories. In the XNUMXth century, in military affairs, light signaling with the help of so-called heliographs was used very often.
The main part of the heliograph is a mirror, with the help of which light rays can be directed to a specific place, where there is another mirror of the same type. The symbols are formed by short turns of the mirrors in one direction or another.
In favorable weather conditions, such signals can be transmitted over a distance of sixty-five kilometers. At night, under the light of the moon, this distance is reduced to fifteen kilometers, and when illuminated by lamps - up to five kilometers.
Features such as simplicity of design and installation, lightness, low cost of mirror heliographs made them quite suitable for military purposes. Used in the army and mainly on military ships and more sophisticated signaling devices with a strong electric light: searchlights. To direct the arc rays with a parallel beam, they used both reflection (spherical or parabolic mirrors) and refraction of light (different types of glass lenses).
At the end of the XNUMXth century, in France, Claude Chappe, a French mechanic who invented the optical telegraph, devised a system for transmitting information using a light signal. It was baptized as "optical telegraph". It simply consisted of a chain of common buildings placed in view of one another. On the roof of the buildings there were poles with movable transverse rods - traffic lights. The traffic lights were controlled by the operators who sat inside with the help of cables.
In addition, Chappe created a group of special codes. Each figure taken by the traffic light corresponded to a letter of the alphabet, depending on the different positions given to the crossbars in relation to the support post. The system devised by Chappe managed to transmit messages at a speed of two words per minute. It was quickly used throughout Europe. In Sweden a chain of optical telegraph stations operated until 1880.
Traffic lights conveyed information more accurately and were more reliable than smoke signals and other signals of the time. In addition, they did not require fuel. Messages could be transmitted faster than messengers were capable of carrying them, and semaphores could transmit messages across an entire region. But nevertheless, like other methods of transmitting signals over a distance, they were highly dependent on weather conditions and required natural light since electric lighting appeared only in 1880.
Many operators were necessary and the towers had to be located at a maximum distance of thirty kilometers. It was useful for the government, but too expensive for commercial use. With the invention of the electric telegraph, the cost of sending messages was reduced thirty times, in addition, it could be used at any time of the day, regardless of the weather.
electric telegraph
The first attempts to apply magnetism and electricity to telegraphy date back to the XNUMXth century and were not very successful.
So, from this early time, the Italian philosopher, alchemist, playwright and researcher Giambattista della Porta, later the German scientist and inventor Athanasius Kircher (1602-1680) and others suggested using magnetic interactions for this purpose. In the eighteenth century there have been attempts to use static electricity for the same purpose.
The first real device was created by the Swiss physicist Georges-Louis Le Sage in Geneva in 1774, he built one of the first working models of an electric telegraph with an electrostatic machine (transmitter) and an electroscope (receiver), which had a separate cable. for each of the twenty-six letters of the alphabet. Whoever invented the telegraph connected two separate rooms in the inventor's house.
However, this signaling method cannot be applied over long distances and was not widely used. This was an attempt that, like others like it, was interesting only from a historical point of view.
The main disadvantage of using static electricity for signaling is that due to the high (potential) voltages extremely careful insulation of the wires was required, which in practice presented great difficulties.
Electrical telegraphy began to develop rapidly and gave really brilliant results only from the moment when it began to use galvanic current. The first such device, based on the chemical action of the current, was built in 1809 by Samuel Thomas von Sömmerring, who is believed to have invented the telegraph in Munich.
A galvanic battery at one station could be connected to two of the thirty-five cables connecting the two stations; the ends of all these thirty-five cables at another station were dipped in a weak solution of sulfuric acid; when the current passed, the liquid decomposed and oxygen was released in one of the cables and hydrogen in the other; each wire was assigned a sign, letter or number, and thus the alarm could be installed over relatively long distances - up to three kilometers.
Pavel Lvovich Schilling was a Russian scientist and electrical engineer, who invented the electromagnetic telegraph, according to many, in 1832 a telegraph line was laid in St. Petersburg between the Winter Palace and the Ministry of Railways building.
The telegraphic transmission device consisted of a keyboard with sixteen keys, which served as current locks of the required direction, and the receiving device contained six multipliers with static magnetic arrows suspended on threads, to which were attached circles of paper, white on the outside. one side and black on the other.
According to other opinions, the one who invented the telegraph was the American physicist Joseph Henry in 1989, and he perfected it in 1835, but Henry did not patent his invention that is why he is ignored, later he helped Samuel Morse to install a telegraph between the North American cities of Baltimore and Washington.
Who invented the electric telegraph was the well-known American doctor, scientist and inventor David Alter, according to many, in 1836, a year before Morse, he installed an electric telegraph between his house and his barn, but he did not make his invention public. In an interview he was asked about this and replied: "I can say that there is no connection between the telegraph of Morse and others and mine. It is very likely that Professor Morse has never heard of me, or my telegraph."
Both stations were connected to each other by eight cables, of which six went to the multipliers, one served for the reverse current and one communicated with the recruiting apparatus, which was a bell with a clockwork mechanism, also activated electromagnetically by diverting a magnetic needle.
By means of the sixteen keys of the transmission device, it was possible to send a current in one direction or another and thus turn the multiplier arrows forward with a white circle, then black, thus conforming to the established signs. Subsequently, Schilling made the operation of the receiving device simpler for him, leaving in it only one multiplier instead of six, and the conditional alphabet was made up of thirty-six different deviations of the magnetic needle.
Schilling used underground cables to connect the stations; he expressed the idea of the possibility of hanging cables on poles. On July 25, 1837, Schilling died, without having time to carry out Nicholas I's orders to connect Petersburg with the city of Kronstadt.
In 1833, the German scientists Carl Friedrich Gauss and Wilhelm Eduard Weber installed an electromagnetic telegraph in the city of Göttingen: their telegraph connected the university's physics office with the magnetic and astronomical observatory and operated by means of induction currents induced by the movement of a magnet inside a coil of wire; these currents at another station caused the multiplying magnet to vibrate.
In the late thirties, various modifications of such electromagnetic telegraphs with arrows appeared, and then they began to spread rapidly. The greatest success in practice fell to the inventor of the English telegraph William Cooke and Charles Wheatstone, who presented a simple improvement over the Schilling device, with which Cooke familiarizes himself in 1836 at a lecture at the University of Heidelberg. The Wheatstone and Cooke devices were used in England from 1837.
Carl August von Steinheil in 1838 in Munich established a telegraph line of five thousand meters, the one that Gauss extended in Göttingen had a distance of only seven hundred meters, and at the same time he made a very important discovery in the history of the telegraph, which significantly reduced the cost of wiring telegraph lines, contributing to the rapid spread of telegraphs.
This discovery was that a single cable is enough to connect two stations, since a reverse current can flow through the ground if one of the poles of a galvanic battery is connected on one side to a large sheet of copper immersed in the moist ground. and, on the other hand, connect the end of the cable to ground in the same way.
The main and essential part of each of these devices is an electromagnet which, when current passes through it, attracts an iron plate and thus moves the pointer in a circle from one sign to another, or, in another system , on the contrary, briefly stops the movement of the pointer in a circle with the help of the clock mechanism and there were already many models of these devices.
The two considered telegraphy systems with the help of magnetic diversion arrows and indicators rotating on the dial have mainly the drawback that transient signs in them easily cause errors, while control is impossible.
Therefore, they gradually began to be replaced by writing devices, as soon as methods for recording the conditional movements of an electromagnet armature in a telegraph receiver were invented and improved, in which a current of greater or lesser was passed duration.
One of the first writing telegraphs was made by the German Russian physicist Boris Semyonovich Jacobi. The symbols for this device were written on a moving porcelain board with a pencil attached to the anchor of an electromagnet. The Jacobi device was installed in 1841 on an underground telegraph line in Saint Petersburg and connected Emperor Nicholas I's office in the Winter Palace with the General Staff.
In 1842, a line was laid from the Winter Palace to the main railway administration, in 1843 - to the Tsarskoe Selo palace. Jacobi improved on his invention in 1850, creating the world's first direct-printing telegraph apparatus.
morse telegraph
Samuel Morse. who invented the telegraph, according to the most general opinion, was an American inventor and painter, Morse met Louis Daguerre and became interested in advances in the field of electricity. He was inspired to invent the telegraph by a casual conversation while returning from Europe in 1832.
One passenger, during a conversation about an electromagnet, said: "If an electric current can be made visible at both ends of the wire, then I see no reason why messages cannot be transmitted." Although the idea of a telegraph was ahead of Morse, he believed that he was the first.
Morse devoted almost all of his time to painting, teaching at New York University, and politics. In 1835 Morse became professor of descriptive arts. But after being shown at the university in 1836 a description of the telegraph model proposed by Wilhelm Weber in 1833, he devoted himself fully to the invention.
It took Morse years of work and study to make his telegraph work. In September 1837, he finally demonstrated his invention. The signal was sent over seventeen hundred feet of cable, but the telegram received from the transmitter was unreadable. But Morse was not going to give up and in less than six months, together with A. Weil, he developed a system of transmitting letters with dots and dashes, which became known throughout the world as Morse code.
On February 8, 1838, in Philadelphia, at the Franklin Institute, he first publicly demonstrated his electromagnetic telegraph system, which transmitted messages using signals in a special encoding.
The Morse telegraph among the various telegraph systems is the most famous and until recently was the most common. Although this device was conceived by Samuel Morse and the first successful results with it were obtained as early as 1837, it was only in 1844 that it was improved by Alfred Weil so that it could be applied to business.
The device is designed very simply. A manipulator or key, which serves to close and interrupt the current, consists of a metal lever, whose axis is in communication with the line cable. The lever with one end is pressed by a spring against a metal projection with a clamping screw, by means of which it is connected with a cable to the receiving apparatus of the station and to the ground. Pressing the other end of the lever touches the other lug connected to the battery.
In this case, therefore, the current will be sent to the line to another station. The main parts of the receiver are: a vertical electromagnet, a lever in the form of a seesaw, and a clock mechanism for pulling a paper tape. An electromagnet, when current passes through it, attracts an iron bar located at the end of the lever; the other arm of the lever rises and presses the steel point at its end against the paper tape, which moves continuously over it by a clockwork mechanism.
When the current is interrupted, the spring pulls the lever back to its original position. Depending on the duration of the current on the tape, the tip of the lever leaves traces in the form of dots or lines. Various combinations of these signs make up the alphabet.
Such marks can be produced directly by pressing the toggle pin into the paper, which will leave bleed marks on the paper. But raised writing devices are inconvenient in that they require quite a significant current to operate.
Therefore, instead of a pin, they began to use a small wheel, which with its lower part is dipped into a container with thick ink. This wheel gradually rotates under the action of the device and leaves a trace of paint on the paper tape.
To increase the speed of action of telegraphic devices, Charles Wheatstone replaced the manual transmission in the Morse system with mechanical transmission. Manual transmission is slow and prone to errors. Therefore, Wheatstone proposed to use in the transfer apparatus a fast-moving paper tape with holes prepared in advance, causing the current to shut off, as a result of which Morse symbols are left on the paper tape of the receiving station. .
Holes are created using a special device - a perforator. It forms three rows of holes, of which the middle one serves to move the tape by means of a rotating gear, and the holes of the outer rows are located according to Morse signs. Two holes located directly above each other correspond to a point, and two holes located in an oblique direction represent a dash.
In the transfer device, two needles are placed under the extreme rows of holes, which, by means of an oscillating rocker, are given a very rapid up and down movement.
When the first needle hits the hole, a system of levers will turn the switch, causing current to flow into the line. When the second needle enters the hole, the switch will turn in the other direction, while the current in the opposite direction will pass through the line.
In the receiving apparatus, in the first case, the anchor of the electromagnet will rotate and bring the pen into contact with the strip of paper, which will draw a line on the paper until the reverse current rotates the armature together with the pen in the other direction. . If the two holes of the transfer device paper tape are directly through the tape, after the first needle, the second needle will immediately enter the corresponding hole, in addition, a very short line appears on the receiving device that corresponds to a point of the Morse alphabet.
When the holes fall obliquely, the line is longer. The transmitter can send up to six hundred words per minute this way. For comparison, the Morse apparatus sent up to thirteen, the Hughes apparatus up to twenty-nine, the Baudot apparatus up to one hundred and twenty words per minute.
As a general rule, three or four telegraph operators are busy punching holes in paper tapes, and each of them can type between thirty and forty words a minute. The same number of people will be busy with the correspondence of the dispatches received.
The Morse code
The Morse alphabet or Morse code is a sign encoding method, which represents letters of the alphabet, numbers, punctuation marks and other symbols with a sequence of signs: long (hyphens) and short (dots). The unit of time is the duration of a point. The duration of a hyphen is three points. A pause between elements of the same character is one period, between characters in a word three periods, between words seven periods. Named after American inventor and artist Samuel Morse.
The letter codes were added by Morse's partner, Alfred Weil, who invented the telegraph, a fact that Morse later denied in every possible way. Weil, however, may have invented the digital part of the code. And in 1848, Morse code was optimized by the German Friedrich Gerke and is still in use today.
The modern telegraphic alphabet known as Morse code is a system by which the characters of messages are encoded in order to be transmitted through communication lines. It is significantly different from the one proposed in 1838 by Samuel Morse, however some attribute the creation of this system to Alfred Weil, a business associate of Samuel Morse, who introduced a code for trading in groups of five letters.
The original Morse code setup was essentially different from the codes used in amateur bands today. First, it used messages of three different lengths. Second, some symbols had pauses within their codes.
The coding principle of Morse code is essentially to simplify the combination of dots and dashes of the characters that are most used in the English language in order to facilitate their learning as well as make transmissions more solid and faster.
Morse code can be transmitted and received at different speeds, depending on the capabilities and experience of the radio operators. Normally, an average radio operator works in a speed range of sixty to one hundred characters per minute. Achievements in high-speed transmission and reception are in the speed range of two hundred and sixty to three hundred and ten characters per minute.
The transmission of Morse codes is carried out by means of a telegraphic key of which there are several models. With sufficient operator qualifications, it is possible to receive short messages without recording, but generally all received text must be typed manually or on a typewriter.
When receiving, experienced radio operators record with a delay of several characters, which makes reception smoother and more reliable and is an indicator of operator skill, at high speeds, above one hundred and fifty characters per minute, the delay can be up to a hundred characters in half a minute; the radio operator has to memorize them and add them after the end of the radiogram.
When receiving at high speeds, more than one hundred and twenty-five characters per minute, you must engrave the texts, abandoning the standard alphabetic characters and using special abbreviated symbols (for example, the "dot" sign for the letter "e" or the "mark of verification” for the letter “g”). In this case, after the reception is finished, the radio operator must translate the text into the symbols of the usual alphabet.
The telegraph and radio telegraph originally used Morse code, later Baudot code and ASCII were used, which are more convenient for automation. However, now even for Morse code there are means of automatic generation and recognition, for example, free software for a personal computer CwType.
submarine telegraph lines
The first submarine cable carrying an electrical signal was laid in Munich along the Isar River. However, due to the lack of sufficient waterproofing, long-term use of such a cable was not possible.
Only the invention in 1847 by Siemens of the technology for manufacturing gutta-percha insulation made it possible to begin work on laying a cable between Calais and Dover, which was broken after the first telegram was sent, a year later an attempt was made to replace it. by a shielded cable, but the latter did not last long.
The Atlantic Telegraph Company was founded in 1856 and in 1857 began laying four thousand five hundred kilometers of armored telegraph cable across the Atlantic Ocean. The cable, which weighed about 1857 pounds per mile, consisted of seven copper wires covered with three layers of gutta-percha and a sheath of iron cords. In August XNUMX, the ships Agamemnon and Niagara began laying from the southwest coast of Ireland, but due to a broken cable, the attempt had to be postponed for a year.
The second attempt was made in the summer of 1858. This time, it was decided to start depositing in the ocean, approximately halfway between Ireland and Newfoundland.
On July 26 "Agamemnon" and "Niagara", each with their half of the cable on board, meeting in the Atlantic Ocean, connected the halves of the cable and lowered it into the water. During the laying process, the cable broke several times and the ships had to return to start over.
On August 5, after a successful laying, the ships reached their destinations, the islands of Valentia and Newfoundland and the first transatlantic telegraph line connecting the Old and New Worlds was laid. On August 16, 1858, Queen Victoria of Great Britain and United States President James Buchanan exchanged congratulatory telegrams.
The Queen's greeting consisted of one hundred and three words, the transmission of which lasted sixteen hours. It was necessary to telegraph at such a slow rate because, due to the enormous capacitance and resistance of the long wire, short current pulses "spread" at the receiving end like ink stains on filter paper.
In September 1858 communication was interrupted. Apparently, due to insufficient waterproofing, the cable was destroyed by corrosion. Another possible reason for the destruction was too high voltages being applied to the line from the English side to speed up the transfer.
In July 1865, the laying of 31 kilometers of cable with improved insulation began, and it was decided to use the largest ship of the time, the British steamer Great Eastern, with a displacement of 1865 tons, as the cable layer. . On July XNUMX, XNUMX, a cable break occurred during laying.
After several unsuccessful attempts to catch the end of the cable with an anchor and raise it to the surface, it was decided to postpone the undertaking until next year.
In 1866, a new cable was laid, providing a long-term telegraph connection between Europe and America. It is curious to note that a severed cable was discovered in 1865, after which it was attached to the missing fragment and was able to function successfully.
A few years later a cable was laid to India, making it possible in 1870 to establish a direct telegraph connection between London and Bombay (via a repeater station in Egypt and Malta).
wireless telegraph
The radiotelegraph, or wireless telegraph, is a device designed to transmit textual information by radio using Morse code or other simple code. In the early period of the development of radio communications, the telegraph was actually the only way to transmit information by radio. Despite the appearance of new and much more effective methods, the radiotelegraph is still used by enthusiastic amateurs, various radio beacons, and less frequently in commercial communications.
Technically, radiotelegraphy can be implemented in various ways, for example: Amplitude manipulation the transmitter emits an unmodulated signal during transmission (dots or dashes) and remains “silent” during pauses.
Frequency shift coding (used less often), in pauses, the transmitter emits a signal of one frequency, and during transmission, another, slightly different.Tone telegraphy with amplitude or frequency modulation. Telegraphic sound transmissions are transmitted in the same way as normal voice radio transmissions.
At the transmitting station, the telegraph signal is established by a human operator using a key or keyboard Morse code sensor, or by an automatic device, for example a punched tape reader or a computer program.
The signal may also be received by an operator (usually by ear) or an automatic recorder of one kind or another. A specially adapted receiver is needed to receive FM shift keyed signals; tone telegraphy signals can be received by any conventional AM or FM radio.
The radio telegraph can be implemented much more cheaply and easily than any other method of radio communication. In the earliest version, amplitude shift keying was done simply by turning the RF oscillator on and off. Receiving such signals is only slightly more sophisticated than receiving conventional radio transmissions. The simplest equipment for radiotelegraph communication may consist of twenty to thirty off-the-shelf pieces and is very easy to set up.
Another advantage of the wireless telegraph is the noise immunity of a radiotelegraph communication line when received by the ear is much greater than, for example, a radiotelephone line. A weak Morse code in a jamming context is much easier to distinguish than a voice. The frequency spectrum of the radiotelegraph signal can be very narrow, so the bandwidth of the receiver can be reduced and interference can be suppressed. Transmission and reception are relatively easy to automate.
In the Radiotelegraph, especially if the operators are people, the connection is quite slow. A trained professional radiotelegraph operator in his daily work does not generally receive and transmit more than XNUMX to XNUMX characters per minute. The fastest ones can work two to three times faster. Morse code does not offer any protection against errors. The operators are therefore fully responsible for the correct reception and transmission. It takes time and effort to train the operator.
Teletype
A teletype is an electromechanical printing machine that is used to transfer text messages between two subscribers through a simple electrical channel, usually a pair of wires. Most advanced teleprinters are completely electronic devices and use a screen instead of a printer. Most teleprinters used a five-bit Baudot code, which limited the number of characters used to thirty-two. But if you enter control characters, the information content can be increased.
The development of teletypes came about thanks to a series of inventions by engineers such as Pavel Schilling, Boris Jacobi, Royal House, David Hughes, Edward Kleinschmidt, Charles Crum, Emile Baudot, and Frederic Creed. The immediate predecessors of the teleprinter are the teletype machines, which came into use in the 1870s to display text transmitted over wires. A specifically adapted telegraph machine was used to send information about the mercantile exchange via telegraph wires to the receiving teletype machine.
In 1855 David Edward Hughes, who invented the printing telegraph, filed a patent for the first telegram printing apparatus. Hughes wanted to create a system to transcribe the musical notes on a sheet of paper as a musical instrument was played and thus automatically write the score. Hughes's telegraph was operated like a keyboard and in fact looked very much like a piano keyboard with black and white keys for letters, figures and various signs.
Whereas Morse's telegraph transmitted twenty-five words a minute, Hughes's printer could transmit sixty words a minute. Another outstanding feature of the Hughes telegraph is that it worked with a clockwork mechanism that was driven by weights, which allowed the synchronization of continuous movements of equal speed both in the wheel of the emitting station and in the wheel of the receiving station.
Unable to market his invention in the United States because the patent belonged to Samuel Morse, Hughes took his system to Europe, it was well received in France, it was tested for a year and then it was accepted by the Directorate of Posts and Telegraphs of that country, in addition he was even decorated by Napoleon II himself. Both the positive reception and the continuing tributes soon spread throughout Europe.
A worldwide network called Telex was created in the 1920s and was used for most of the XNUMXth century for business communications.
The network is still used by some countries in areas such as shipping, news, interbank payments, communications for ground aviation services, and for military commands. Until the early 1970s, it was with the help of a teletype that messages were exchanged on the so-called "hot line" that connected the president of the United States with the leaders of the USSR.
In the early days of computing, some computers (such as the LGP-30) used teleprinters to input and send information. Teletypes were also used as the first interactive computer terminals.
They had no video screens; users had to type commands after receiving a special character - an invitation to enter information. This is how text terminals, the command line interface, and even the string data type, text data in general, and text files in particular, came into being.
In the mid-XNUMXs, the popularity of the teletype fell dramatically, although radio amateurs still work both on equipment made in the XNUMXs, as well as on computers, tablets and smartphones, after having installed the necessary software.
Although the ability to transmit text containing news and messages over distance is used in the modern world, teleprinters, which require separate dedicated pairs of wires, are replaced by fax machines, personal computers, high-speed networks, and the Internet.
telegraph key
The telegraph key is a term in general use to refer to any mechanism that is used especially to transmit characters primarily using Morse code. These keys are specifically used for handheld telegraphy, as in electric telegraph and radio telegraphy.
The conventional telegraph key is a spring-loaded rocker, swinging in a vertical plane, mounted on a sufficiently stable base. By pressing the end of the rocker arm, the operator makes a single electrical contact.
Spring tension and rocker arm travel (contact gap) are adjustable for operator comfort. Less common are the specimens with horizontal movement of the rocker. There are keys on which there are two contacts: one works to close, the second - simultaneously - to open the circuit.
There are several known methods of working with a mechanical key. The operator's hand can rest on the table with the entire forearm, lean with the elbow or be suspended; the key is pressed with the movement of the fingers or the wrist; the fingers rest on the key head differently.
At different times, in different countries and different departments, this or that method prevailed. Accordingly, different keys were used: with a large rounded head or, conversely, with a flat one and lowered to the table, with or without support for the fingers under the head.
The ability to operate a mechanical key is considered a basic skill for a radio operator, regardless of how often you use it in practice. Until recently, for example, in order to obtain an amateur radio license, it was necessary to pass a mandatory examination in the reception of radiograms by ear and transmission on a mechanical key, now in many countries this requirement has been greatly relaxed.
The transfer rate in the mechanical key is low. In practice, rarely more than one hundred to one hundred and twenty characters are transmitted per minute. Only highly trained receivers work faster.
The semi-automatic mechanical telegraph key was invented by Horace G. Martin in 1890, and in 1904 he received a patent for this invention. On this key, the key rocker is swung horizontally in both directions.
By pushing the rocker to the left, the operator manually transmits a dash. Pressing to the right starts the pendulum, a mechanism that automatically generates a sequence of points; when the operator releases the rocker arm, the point drive stops.
The speed at which the points are formed is regulated by moving the weight on the pendulum. Such keys, known as "vibroplex" after the name of the company that first brought them to market, and similar designs became widespread in the first half of the XNUMXth century, then were largely replaced by electronic keys. There are also known mechanical keys that not only generate dots, but also dashes.
Semi-automatic electronic keys are controlled by two contacts. When one of them is closed, the electronic circuit forms a series of points; when the other is closed, a series of dashes. The electronic key allows you to easily adjust the transmission speed, the relationship between the duration of messages and pauses, and hold them with great precision.
The first semi-automatic electronic devices appeared in the XNUMXs and XNUMXs and were built on vacuum tubes. There were also purely electromechanical devices without electronic components. Modern electronic keys built on microcontrollers, often supplied with additional functions.
Recently, so-called "iambic" keys have gained popularity. If both control contacts of that key are closed at the same time, it begins to form a “dot-dash-dot-dash” or “dash-dot-dash-dot” sequence, depending on the configuration. This is useful for some Morse codes and allows the operator to make fewer moves. Naturally, to take advantage of this opportunity, you need a key that allows you to close two contacts at once.
Telex
The telex network was a client-to-client interconnection network of teleprinters similar to a telephone network, using telegraph-grade connection circuits for two-way text messages.
After the Second World War, the telex was widely used by companies for written communication between their commercial allies. With the appearance of the fax in the eighties of the last century, its use gradually lost popularity.
When speaking of “telex”, it is the one of the transmitter and receiver, the teleprinter, and not of the equipment. Teleprinters have been in use since about the XNUMXs and were developed in conjunction with telegraphy systems, using binary signals with codes triggered by the pulses or lack of electrical pulses.
In 1930, the design of a start-stop telegraph apparatus, equipped with a disk-type telephone dialer (teletype), was created. This type of telegraph device, among other things, made it possible to personify the subscribers of the telegraph network and make them connect quickly. Almost simultaneously in Germany and Great Britain national subscriber telegraph networks, called Telex (TELEgraph EXchange), were created.
On the basis of the international agreements of the 1930s, the telex was recognized as a document and the telex, respectively, as a type of documentary communication. A little later, the United States also created a national subscriber telegraphy network similar to Telex, which was called TWX (Telegraph Wide area eXchange). International subscriber telegraph networks were constantly expanding, and in 1970 a worldwide network called the Telex Network was created with united subscribers in over a hundred countries around the world.
It wasn't until the XNUMXs, with the advent of convenient and inexpensive fax machines, that the PSC network began to lose ground to fax communication.
Phototelegraphy and communication by fax
In 1843, Scottish physicist and watchmaker Alexander Bane demonstrated and patented his own project for an electric telegraph, which could transfer images through wires. The equipment designed by Bane is considered the first fax machine.
In 1855, the Italian inventor Giovanni Caselli created a similar device, which he called the pantelegraph, and proposed it for commercial use. The first commercial pantelegraph line between Paris and Lyon began operating in 1865, eleven years before the invention of the telephone by Alexander Bell. Caselli's apparatus transmitted the image of a text, a drawing, or a painted drawing on a sheet of lead with a special insulating varnish.
The contact pin slid over this set of intermittent areas of high and low conductivity, "reading" the elements of the image. The transmitted electrical signal was recorded on the receiving side by an electrochemical method on moistened paper soaked in a potassium ferrocyanide solution. The pantelegraph was used on the lines of communication between Moscow and Petersburg, between Paris and Marseille, and between Paris and Lyon.
A technological breakthrough is associated with the discovery of the photoelectric effect and its laws at the end of the 1902th century. German inventor Arthur Korn demonstrated in 17 the first photovoltaic system to send static images, which he called "telephotography". The device became famous on March 1908, XNUMX, when a photograph of a wanted criminal was sent from Paris to London in twelve minutes, which was instrumental in his arrest.
However, due to the inherent inertia of all selenium photocells, the device's baud rate could not be increased in any way. Almost simultaneously in France, Edouard Belén designed the belinograph, which was later used for the first transmission of a photograph across the Atlantic Ocean.
The belinograph did not contain photocells, but read the relief obtained by tanning chrome gelatin whitener on special photographic paper. Despite the specific printing technology, the belinograph gained popularity in Europe for several decades due to its high image transfer speed.
Since the 1920s, thanks to the invention of electronic tubes and amplifiers of electrical oscillations based on them, there has been a new breakthrough in the development of facsimile communication.
One of the first mainstream technologies was the photo telegram, developed by AT&T engineer Herbert E. Ives with input from Harry Nyquist. The device was introduced to the public on May 19, 1924, when fifteen photographs were transferred from Cleveland to New York, destined for newspapers. The image was captured in a photosensitive photographic material, after being developed the photo was obtained.
For several decades, the technology was the standard in news photojournalism, where it was used for rapid delivery of photographic information about a scene, as well as for distribution to clients. The regular use of this technology was initiated by the Associated Press agency, on February 12, 1935, an image captured in the west was transferred for the first time to the east coast of the United States.
In the 1930s, the USSR created its own phototelegraphic devices that worked on the same principle. In 1959, the Japanese newspaper Asahi transferred the finished pages by phototelegraph from the editorial office in Tokyo to the printing house in Sapporo, pioneering decentralized printing technology for daily newspapers. In the same way, weather charts for ship crews began to be distributed.
An additional stimulus for the development of phototelegraphy in the USSR was the expansion of contacts with the People's Republic of China, where the documents contained hieroglyphs, the transmission of which by ordinary telegraph was difficult. In the United States, Ticket fax machines were used to transfer train tickets from central ticket offices to urban and suburban offices.
Despite the adequacy of the public telephone network, this type of communication did not become widespread, as devices from different manufacturers were incompatible and difficult to manage. To organize photo-telegraphic communication between two points, it was required to install a receiver and a transmitter of a system, as well as a qualified operator. Most of these lines were intended for specific departmental purposes, assuming no arbitrary choice of the subscriber.
The further development of voice telephony and the improvement in the quality of communication led to the standardization of video transmission protocols compatible with telephone communication channels.
The modern version of the fax arrived in 1964, thanks to the Xerox company, to create a "remote photocopier". Two years later, the company launched the Magnafax fax machine, which weighed "only" forty pounds. The device was very easy to operate compared to all previous designs, taking only six minutes to transfer a page over a standard telephone line.
Thanks to advances in fax machines, in 1966 the International Telecommunications Union approved the first international standards for analog fax transmission. However, faxes became a form of mass communication only after 1978, when the ITU Telecommunication Standardization Sector approved new international standards endorsed by most office equipment manufacturers.
The new standard has reduced the page transfer time from six to three minutes with the same clarity. The fax boom came in the late 1970s, when numerous machine manufacturers entered the market. Xerox continued to advance technology by integrating the fax and copier into one device. Today, fax is being replaced by multifunctional devices that also combine fax communication.
The modern fax machine competes with email and other means of transferring graphic files, but its role in modern business is declining relatively slowly.
In addition to the convenience and simplicity of this type of communication, the prevalence of fax machines, the ability to transmit color images, as well as the reluctance of some organizations to switch to other communication methods, play an important role, since this it will require investments and efforts to train staff. Also, modern fax machines have the ability to use regular writing paper instead of the special thermal paper previously used.
Until the advent of modern fax machines in the late 1970s, most devices worked similarly to phototelegraphic equipment: the original was wound onto a rotating drum and spirally scanned by a light-sensitive sensor. . However, the resulting pulsing current was not transmitted directly to the receiver, but was instead used to modulate the audio carrier according to the pitch of the transmitted section.
The devices of those years were made as accessories to an ordinary telephone and contained an acoustic modem for the earpiece, equipped with a microphone and a speaker. After communicating with the subscriber over the telephone line, the device was switched to receive mode, and the telephone receiver was placed on the modem so that the microphone on the receiver was facing the speaker on the modem and vice versa. Thus, the telephone line transmitted the sound obtained by modulating the carrier frequency with a fax video signal.
After demodulation in the receiving apparatus, the received signal was fed to a device that pressed the ink onto a plain sheet of paper wound on the same rotating drum. This operating principle has become obsolete with the proliferation of digital technology and charge communication devices, which have simplified image scanning. In Group Four faxes, a CCD line with 1782 reading elements is used for this, installed in front of the drum, which moves the transmitted sheet at low speed.
When the original moves beyond the ruler, the frame memory forms a file with a complete image. The revolution in fax transmission was brought about in the late 1960s by the Dacom DFC-10, which used technology developed by the Lockheed Corporation to receive photographs from satellites to compress the digital stream.
This made it possible to shorten the page transfer time without the need to improve the communication channel. The receiving process has also been simplified through the use of thermal printing on specialty paper since the late 1970s. In the 1990s, roll-to-roll thermal printing gave way to flat-bed inkjet printers. flatbed or similar thermal transfer devices that did not require expensive specialty paper and compatible color printing.
Before the introduction of modern digital standards and printers, most fax machines were only suitable for transmitting and receiving originals online and did not produce high-quality grayscale copies. This was due to the complexity of reproduction by prevailing printing methods and, mainly, to the purpose of the facsimile, which serves to transfer text and handwritten documents.
Modern fax machines are capable of transmitting and reproducing not only grayscale, but also full color images scanned by a flatbed scanner.
As the cost of computer equipment and access to the Internet became cheaper, more and more often a general-purpose computer connected to the network was used to transfer images, which has a printer and a scanner. For usage purposes, this type of computer sometimes has a separate name "Office Computer." In some cases, the use of such a computer in the image transfer process was also called "fax communication."
The main advantage over traditional fax is that there is no need for synchronous and phased operation of all elements of the communication path. Thanks to the created fax gateways, there is absolutely no exact boundary between traditional fax communication and computer communication. The development of computer technology and mathematical apparatus made it possible to "save" the bandwidth of the lines.
The telegraph in the XNUMXst century
Today, Telex's messaging capabilities have been largely preserved by email. In some countries, telegraphic communication still exists today, telegraphic messages are transmitted and received using special devices - telegraphic modems, coupled in electrical communication centers with personal computers of operators.
However, the transmission of messages in most cases is already carried out through modern communication channels, the wired telegraph network in most of the world's territory has been dismantled.
In some countries, the national operators considered the telegraph as an obsolete form of communication and restricted all operations of sending and delivering telegrams in the traditional sense of the term. In the Netherlands, telegraph services stopped operating in 2004. In January 2006, the oldest US national operator, Western Union, announced the complete cessation of services to the population for sending and delivering telegraph messages.
In July 2013, the telegraph office was closed in India, in 2017 in Belgium, in March 2018 in Ukraine. At the same time, in Canada, Germany, Sweden, Japan, some companies still offer services for sending and delivering traditional telegraphic messages.
high speed radio telegraphy
High-speed Radiotelegraphy is a radio sports discipline where radio amateurs are challenged to receive, copy and sometimes accurately send messages using Morse code at very high speed. This form of sport is popular in Eastern Europe, where even international competitions are organized by the International Amateur Radio Union (IARU).
High-speed radiotelegraphy originated from contests for the skill of radiotelegraphers. Nowadays, there are many different types of communication, from the Internet to mobile phones, however, in the recent past, communication at sea, in geological and polar expeditions, in the military, etc. It was done by telegraph, using Morse code. For his need the ability to quickly transmit Morse code with a key and receive it by ear was much appreciated.
In high-speed radiotelegraphy competitions, the athlete must receive a text of a certain speed, written by hand or on a typewriter, in one minute. Then the speed is increased by ten characters per minute. The speed is valid if the athlete has not committed more than five faults. The number of points an athlete gets depends on the fastest speed they get. In total, three different speeds are allowed to pass.
The athlete can compete using a normal key or a special or electronic one. The electronic key has three positions. The middle is off. On the right, strings of dots are transmitted, on the left, strings, dashes, or vice versa. The athlete manipulates the key from left to right and the electronics of the key forms the necessary characters in Morse code. It is possible to transfer using an electronic key much faster than using a simple key. Therefore, to work on a simple key, the points obtained are multiplied by a factor of 1,3.
The judges listen to the athlete's transmission in their own headphones, verify the transmission with the text of the radiogram, identify errors and evaluate the quality of the transmission. The highest score is one and the lowest is zero. Points are awarded by multiplying the speed displayed by the average score awarded by the judges.
High-speed radio telegraphy competitions also include exercises for high-speed reception of amateur radio callsigns on a computer, using specialized software. These exercises were introduced to the high-speed radio telegraphy competition schedule in the late XNUMXs to attract shortwave radio amateurs.
There are two of these exercises. One of them is «Rufz», where an athlete accepts fifty calls in a row, and if the call is accepted correctly, the speed increases, and if not, it decreases. Second, "Morse Runner" is an imitation shortwave test that lasts ten minutes. In these exercises, the highest result is equal to one hundred points and the least successful results are evaluated as a percentage.
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