The newest telegraph devices. Telegraph communication

At school, for the summer, they always asked an overwhelming list of literature - usually I was not enough for more than half, and I read that all in a short summary. "War and Peace" on five pages - what could be better ... I'll tell you about the history of telegraphs in a similar genre, but the general meaning should be clear.

The word "Telegraph" comes from two ancient Greek words - tele (far) and grapho (writing). In the modern sense, it is just a means of transmitting signals through wires, radio or other communication channels ... Although the first telegraphs were wireless - long before they learned to correspond and transmit any information over long distances, people learned to knock, wink, make fires and pounding drums - all this can also be considered telegraphs.

Believe it or not, in the past in Holland, messages were transmitted (primitive) with the help of windmills, of which there were a huge number - they just stopped the wings in certain positions. Perhaps it was this that once (in 1792) inspired Claude Schaff to create the first (among the non-primitive) telegraph. The invention received the name "Heliograph" (optical telegraph) - as you might guess from the name, this device made it possible to transmit information due to sunlight, or rather, due to its reflection in a system of mirrors.

Between the cities, in line of sight from each other, special towers were erected, on which huge articulated wings of semaphores were installed - the telegraph operator received the message and immediately transmitted it further, moving the wings with levers. In addition to the installation itself, Claude also invented his own symbolic language, which thus made it possible to transmit messages at a speed of up to 2 words per minute. By the way, the longest line (1200 km) was built in the 19th century between St. Petersburg and Warsaw - from end to end the signal passed in 15 minutes.
Electric telegraphs became possible only when people began to study more closely the nature of electricity, that is, around the 18th century. The first article on the electric telegraph appeared in the pages of a scientific journal in 1753 under the authorship of a certain “C. M. " - the author of the project proposed sending electric charges along numerous insulated wires connecting points A and B. The number of wires had to correspond to the number of letters in the alphabet: “ The balls at the ends of the wires will electrify and attract light bodies with letters.". Later it became known that under C. M. " Scottish scientist Charles Morrison was hiding, who, unfortunately, was never able to get his device working properly. But he acted nobly: he treated other scientists with his developments and gave them an idea, and they soon proposed various improvements to the scheme.

Among the first was the Geneva physicist Georg Lesage, who in 1774 built the first working electrostatic telegraph (he also proposed laying telegraph wires underground in clay pipes in 1782). All the same 24 (or 25) wires isolated from each other, each has its own letter of the alphabet; the ends of the wires are connected to an "electric pendulum" - by transferring a charge of electricity (then still rubbing ebonite sticks with might and main), one can make the corresponding electric pendulum of another station go out of balance. Not the most quick option(transmission of a small phrase could take 2-3 hours), but at least it worked. Thirteen years later, LeSage's telegraph was improved by the physicist Lomon, who reduced the number of wires required to one.

Electric telegraphy began to develop intensively, but really brilliant results gave only when they began to use not static electricity, but galvanic current - food for thought in this direction was first (in 1800) thrown by Alessandro Giuseppe Antonio Anastasio Gerolamo Umberto Volta. The first to notice the deflecting effect of a galvanic current on a magnetic needle in 1802 was the Italian scientist Romagnesi, and already in 1809 the Munich academician Sömmering invented the first telegraph based on the chemical actions of current.

Later, a Russian scientist, namely Pavel Lvovich Schilling, decided to participate in the process of creating the telegraph - in 1832 he became the creator of the first electromagnetic telegraph (and later - also the original code for work). The design of the fruit of his efforts was as follows: five magnetic arrows, suspended on silk threads, moved inside the "multipliers" (spools with big amount turns of wire). Depending on the direction of the current, the magnetic needle went in one direction or another, and a small cardboard disk turned together with the arrow. Using two directions of current and original code(composed of disc deflection combinations of six multipliers), all letters of the alphabet and even numbers could be transmitted.

Schilling was asked to make a telegraph line between Kronstadt and Petersburg, but in 1837 he died and the project froze. Only after almost 20 years it was resumed by another scientist, Boris Semyonovich Yakobi - among other things, he thought about how to record the signals received, began to work on a writing telegraph project. The task was completed - the conventional icons were written down with a pencil attached to the anchor of the electromagnet.

Also, their electromagnetic telegraphs (or even a "language" for them) were invented by Karl Gauss and Wilhelm Weber (Germany, 1833) and Cook and Wheatstone (Great Britain, 1837). Oh, I almost forgot about Samuel Morse, although I already did about him. In general, we have finally learned how to transmit an electromagnetic signal over long distances. It started - at first simple messages, then correspondent networks began to telegraph news for many newspapers, then whole telegraph agencies appeared.

The problem was the transmission of information between continents - how to stretch more than 3000 km (from Europe to America) wires across the Atlantic Ocean? Surprisingly, this is exactly what they decided to do. The initiator was Cyrus West Field, one of the founders of the Atlantic Telegraph Company, who arranged a hard party for local oligarchs and convinced them to sponsor the project. As a result, a "ball" of cable weighing 3,000 tons (consisting of 530 thousand kilometers of copper wire) appeared, which by August 5, 1858 had been successfully unwound along the bottom of the Atlantic Ocean by the largest warships of Great Britain and the United States at that time - Agamemnon and Niagara ... Later, however, the cable broke - not the first time, but it was repaired.

The inconvenience of the Morse telegraph was that only specialists could decipher its code, while it was completely incomprehensible to ordinary people. Therefore, in subsequent years, many inventors worked to create an apparatus that would register the text of the message itself, and not just the telegraph code. The most famous among them was the direct-printing device Yuze:

Thomas Edison decided to partially mechanize (facilitate) the work of telegraph operators - he suggested eliminating human participation altogether by recording telegrams on punched tape.

The tape was made on a reperforator - a device for punching holes in a paper tape in accordance with the signs of the telegraph code received from the telegraph transmitter.

The reperforator received telegrams at transit telegraph stations, and then transmitted them automatically - using the transmitter, thereby eliminating the time-consuming manual processing of transit telegrams (sticking the tape with the characters printed on it onto the form and then transmitting all the characters manually from the keyboard). There were also reperfootransmitters - devices for receiving and transmitting telegrams, performing the functions of a reperforator and a transmitter at the same time.

In 1843, faxes appeared (few people know that they appeared before the telephone) - they were invented by the Scottish watchmaker, Alexander Bain. His device (which he himself called Bane's telegraph) was capable of transmitting copies of not only text, but also images (albeit in disgusting quality) over long distances. In 1855, his invention was improved by Giovanni Caselli, improving the quality of image transmission.

True, the process was quite laborious, judge for yourself: the original image had to be transferred onto a special lead foil, which was “scanned” by a special pen attached to the pendulum. Dark and light areas of the image were transmitted in the form of electrical impulses and reproduced on the receiving device by another pendulum, which “drew” on a special moistened paper soaked in a solution of potassium iron-cyanide. The device was called the pantelegraph and later enjoyed great popularity all over the world (including Russia).

In 1872, the French inventor Jean Maurice Émile Baudot designed his own reusable telegraph - it had the ability to transmit two or more messages over one wire in one direction. The Bodo apparatus and those created according to its principle were called start-stop.

But in addition to the device itself, the inventor also came up with a very successful telegraph code (Baudot Code), which later gained great popularity and was named International Telegraph Code No. 1 (ITA1). Further modifications to the design of the start-stop telegraph apparatus led to the creation of teleprinters (teletypes), and the unit of information transmission speed, the baud, was named in honor of the scientist.

In 1930, the start-stop telegraph with a rotary dial telephone type (teletype) appeared. Such a device, among other things, made it possible to personalize the subscribers of the telegraph network and to make their quick connection. Later, such devices were called "telex" (from the words "telegraph" and "exchange").

In our time, telegraphs in many countries have been abandoned as a morally outdated method of communication, although in Russia it is still used. On the other hand, the same traffic light can also to some extent be considered a telegraph, and it is used already at almost every intersection. So wait, write off old people;)

For the period from 1753 to 1839 in the history of the telegraph, there are about 50 different systems - some of them remained on paper, but there were also those that became the foundation of modern telegraphy. Time passed, the technology and the appearance of devices changed, but the principle of operation remained the same.

What now? Inexpensive SMS messages are slowly leaving - they are being replaced by all kinds of free solutions like iMessage / WhatsApp / Viber / Telegram and all sorts of asek-Skype. You can write a message “ 22:22 - make a wish»And to be sure that a person (possibly located on the other side of the globe) will most likely even have time to guess it. However, you are no longer small and understand everything yourself ... better try to predict what will happen with the transfer of information in the future, after a period of time similar in length?

Photo reports from all museums (with all telegraphs) will be published a little later on the pages of our "historical"

Telegraph devices, lines, current sources constitute the main elements of telegraph communication

All telegraph messages are transmitted at a specific rate. The speed of telegraphy is measured by the number of elementary telegraph parcels transmitted in 1 s. The unit of telegraphy speed is Baud (introduced in 1927).

If, for example, 50 telegraphic chips per second are transmitted on any communication line, then the telegraphing rate is 50 Baud. In this case, the duration of one elementary message is 1/50 = 0.02 s = 20 ms.

The receiver of the telegraph apparatus is an electromagnet, through the windings of which the current flows from the line. With the help of an electromagnet, energy is converted electric current into the mechanical energy of the motion of the recording device of the telegraph apparatus.

An electromagnet consists of a winding, a core and an armature. The current from the line flows through the winding, as a result, a magnetic field is formed, acting on the armature, which is attracted to the core, turning around its axis.

When the current telegraph message stops, the field in the core disappears, and the armature returns to its original position under the action of the spring.

A linear relay is used for more reliable operation of the telegraph apparatus at lower currents; it is switched on between the communication line and the electromagnet of the telegraph apparatus.

Distinguish between the methods of telegraphy by the nature of the transmission of current when transmitting code combinations from one station to another and by the method of coordinating the rhythms of the work of the receiving and transmitting apparatus.

Codewords can be transmitted by constant or alternating current.

In direct current wiring, a distinction is made between single-pole and double-pole telegraphy. When messages of current of one direction (positive or negative) are transmitted into the line, telegraphy is called unipolar and the pause between the messages corresponds to the absence of current in the line. This method is also called passive pause wiring.

When a working message is transmitted with a current of one direction (for example, plus), and a pause with a current in the other direction (for example, minus), such telegraphy is called bipolar or telegraphy with an active pause.

Unipolar telegraphy uses one line battery at one station. Two-pole wiring requires two line batteries, each connected to the line through a transmitter with different poles. If the transmitter and receiver work synchronously and in phase, then this method of telegraphy is called synchronous.

The start-stop method of wiring is currently used. The origin of this name is explained by the fact that the valve starts to work only on the signal "start" and after each cycle stops on the signal "stop". To start and stop the distributor with the start-stop method, along the line, in addition to information messages, it is necessary to transmit two more service messages - start and stop.

The synchronous method in combination with the start-stop method is called the synchronous-start-stop method. This method allows wiring over one line from several start-stop devices using a synchronous distributor.

In DC wiring, the range is limited by the distance at which, on the receiving side of the line, the amplitude of the DC sending is sufficient to trigger a receiving electromagnet or relay. To increase the telegraphy range, it is necessary to increase the DC voltage or turn on the transmission of pulses. However, amplification of DC voltage is fraught with significant technical difficulties, and the use of translations is limited by the accompanying distortion of pulses. Sending multiple messages in DC bursts requires a separate communication line for each message.

An increase in the telegraphy range and an increase in the efficiency of use (consolidation) of a communication line are easily solved using frequency telegraphy (alternating current telegraphy). In this case, the telegraphing range is not limited, since it is easy to organize the amplification of AC signals. Due to the compaction of communication lines, several tens of telegraph messages can be transmitted simultaneously.

Range of telegraphy is called the greatest distance between two stations, at which it is possible to carry out reliable transmission of messages without the use of any intermediate amplifying devices.

With facsimile telegraph communication, a still image is transmitted through electrical communication channels. The source of the message to be transmitted can be textual, graphic or photographic material. A feature of facsimile communication is the brightness of elementary areas and their density on the surface of the transmitted image, called the original. On the receiving side, the distribution of the elements of the original must be reproduced with a given accuracy. The image obtained at the receiving end is called a copy.

Subscriber telegraph is used to organize temporary direct telegraph communications between various subscribers. The station equipment includes switching devices and relay panels containing telegraph and telephone relays, which ensure the conversion and transmission of signals and the necessary control of switching processes. According to the method of switching, stations are divided into two types: manual stations - (ATR) and automatic (ATA).

The ATR station is a complex of switching equipment in which all connections are made by a telegraph operator using manual cord pairs. Such stations remained in the network in small numbers and in the future will be completely replaced by automatic stations.

The subscribers included in the ATA station themselves control the process of establishing a connection using the dialer. Automatic connections are possible both with the subscriber included in the ATA station, and with the subscriber included in the ATR station, by calling the telegraph operator of this station.

By the type of switching equipment used, ATA are subdivided into decade-step and coordinate.

In terms of capacity, decade-step stations can be divided into three main types:

Type I - ATA-57 with a capacity of up to 1000 subscriber units;

Type II - ATA-57 with a capacity of up to 300 subscriber units;

Type III - ATA-M with a capacity of up to 20 subscriber units.

Coordinate stations are divided into two types according to their capacity:

Type I - high-capacity ATA-K stations, to which up to 500 subscriber units can be connected;

Type II - small capacity ATA-MK stations, to which up to 20 subscriber units can be connected.

Large-capacity decade-step and coordinate stations are designed for installation in large telegraph nodes with a large number subscriber installations and significant transit traffic, and small-capacity stations such as ATA-M and ATA-MK are installed in small telegraph nodes.

The equipment of ATA stations is built in such a way that it allows to use jointly channels for the subscriber telegraph (AT) network and direct connections (PS) on the trunk section. At the same time, due to operational differences, the switching equipment of automatic stations (ATA) and automatic stations of direct connections (APS) is constructed in such a way that direct connection of the subscribers of these stations to each other was technically impossible.

Direct connection switching stations (APS) are intended for the organization of temporary direct telegraph communications between the terminal points of the telegraph network.

In addition to those listed, the country's telegraph network includes a network of non-commutated (leased) channels.

In accordance with the various requirements of users, three switching methods are currently used in telegraph networks: switching channels (cc), messages (cc) and packets (cp).

At circuit switching an end-to-end channel is organized between the calling and called subscribers with the help of circuit switching nodes, through which information is transmitted.

V this method switching, the procedure for establishing connections begins with making a call. If the station is ready to receive the number, it sends a dialing invitation signal to the caller. The subscriber transmits to the station the number of the called subscriber.

The switching station, having received the number of the called subscriber, determines the direction of the adjacent station and sends it the received number. The incoming station looks for the line of the called subscriber and, if it is free, establishes a connection path between the subscribers. The connection signal is sent to the caller. Through the formed path, messages are transmitted both in one direction and in the other direction. After the end of the two-way exchange of messages, one of the subscribers sends a clear signal and the established connection is disconnected.

Commutation messages This is a method of information distribution in which separate messages are transmitted on the network, provided with headers, including the recipient's address and service information. At each node, the message is written into a memory device, the address is analyzed and the further direction of transmission is selected. If there is a free channel in this direction of transmission, then the message is transmitted immediately, otherwise the message is put into the queue, in which it will remain until the channel is released.

The subscriber sends a message to the switching center (MSC) a request to transfer the message. If the MCC is ready to receive a message, it sends the caller an invitation signal to send a message. The subscriber transmits the message to the center. Having fully received the message from the subscriber, the CCS sends him a confirmation signal. At the end of the route, messages are transmitted at a low speed. On discrete channels between MSCs, the transmission rate is usually higher, as indicated by the change in the message transmission duration. In each center, the received message is recorded in a drive, on magnetic tapes or magnetic disks... The message header is analyzed and the direction of subsequent transmission is determined. All incoming messages are distributed among outgoing directions. When the channel is released, the message is sent to the adjacent switching center, where the process is completely repeated.

Packet switching This is a method of distributing information in which messages are divided into separate blocks, each of which is equipped with a special header. In the switching center, blocks are processed and written to random access memory (RAM). The header is analyzed and the direction of subsequent transmission of the packet is determined. If the channel in this direction is free, the packet is transmitted; if it is busy, the packet is queued for transmission.

There are two methods of packet switching: datagram and method of transmission of packets over a virtual channel. In the datagram method, each packet is transmitted independently of the other packets of the same message, with different packets of the same message being transmitted along different routes. Therefore, packets arrive at the receiving switching node in an arbitrary order with different times delays. At the receiving node, the true order of the packets in the message is restored, the packet headers are erased, and the restored message is transmitted to the recipient.

When transmitting packets over virtual channels, the "Call Request" service packet is first transmitted, laying the only route in the network along which all other packets of this message will be transmitted. The number of the established logical channel is assigned to this route. In the process of transmission, each packet is assigned a logical channel number, according to which everyone participating in the organization of the virtual channel determines the direction of further packet transmission. All packets of one message are sequentially transmitted one after another with exact equal delays. At the destination node, all packets are collected and the recovered message is forwarded to the recipient. After delivery of the entire message, one of the subscribers transmits a service packet "disconnect request", which, passing through the switching nodes, destroys the number of the virtual channel recorded in them, leading to its destruction.

ELECTRIC TELEGRAPH II. 1. Electric bell. 2 and 3. Double wire insulator. 4. Insulator in an iron frame. 5. Bell for alternating currents. 6. Connection of wires. 7. Relay. 8. Writing telegraph device, ordinary German. 9. Thomson siphon marker. 10. Polarized writing telegraph apparatus Siemens and Halske. 11. Receiving device Morse. 12. Morse key.

Primitive types of communication[ | ]

Since time immemorial, humanity has used various primitive types of signaling and communication for the purpose of ultra-fast transmission important information in cases where, for a number of reasons, traditional types of postal messages could not be used. The fires lit in elevated areas of the terrain, or the smoke from the fires, was supposed to notify the approach of enemies or an impending natural disaster. This method is still used by those lost in the taiga or by tourists experiencing a natural disaster. Some tribes and peoples used certain combinations for these purposes. sound signals from percussion (for example, talking drums and other drums) and horns (hunting horn) musical instruments, others have learned to convey specific messages by manipulating reflected sunlight with a system of mirrors. In the latter case, the communication system received the name " heliograph", Which is a primitive light telegraph.

Optical telegraph[ | ]

Om Morse transmission using a ship's optical telegraph (Rattier lamp)

Semaphores could convey information with greater accuracy than smoke signals and beacons. Moreover, they did not consume fuel. Messages could be transmitted faster than messengers could transmit them, and semaphores could carry 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 daylight (Practical electric lighting appeared only in 1880). They needed operators, and the towers had to be located 30 kilometers apart. This was useful to the government, but too expensive to use commercially. The invention of the electric telegraph made it possible to reduce the cost of sending messages thirty times, and it could be used at any time of the day, regardless of the weather.

Electric telegraph[ | ]

Electromechanical telegraph circuit

One of the first attempts to create a means of communication using electricity dates back to the second half of the 18th century, when J.-L. Lesage built an electrostatic telegraph in Geneva in 1774. In 1798, the Spanish inventor Francisco de Salva (d) created his own design of an electrostatic telegraph. Later, in 1809, the German scientist Samuel Thomas Semmering built and tested an electrochemical telegraph using gas bubbles.

Major telegraph lines for 1891

Phototelegraph [ | ]

In 1843, Scottish physicist Alexander Bane demonstrated and patented his own design for an electric telegraph, which allowed images to be transmitted over wires. Bane's machine is considered the first primitive fax machine.

In 1855, the Italian inventor Giovanni Caselli created a similar device, which he called the Pantelegraph, and proposed it for commercial use. Caselli machines were used for some time to transmit images by means of electrical signals on telegraph lines both in France and in Russia.

Caselli's apparatus transmitted an image of a text, drawing or drawing painted on lead foil with a special insulating varnish. The contact pin slid over this set of intermittent high and low conductivity areas, “reading” the image elements. The transmitted electrical signal was recorded on the receiving side by an electrochemical method on moistened paper soaked in a solution of potassium ferricyanide (potassium ferricyanide). Caselli devices were used on the communication lines Moscow-Petersburg (1866-1868), Paris-Marseille and Paris-Lyon.

The most advanced of the phototelegraphs read the image line by line with a photocell and a light spot that ran around the entire area of ​​the original. The luminous flux, depending on the reflectivity of the original area, acted on the photocell and was converted by it into an electrical signal. This signal was transmitted via a communication line to a receiving apparatus, in which a light beam was modulated in intensity, synchronously and in phase around the surface of a sheet of photographic paper. After the development of photographic paper, an image was obtained on it, which is a copy of the transmitted - phototelegram... The technology has found wide application in news photojournalism. In 1935, the Associated Press was the first to establish a network of news bureaus equipped with photographic telegraphs capable of transmitting photographs over long distances directly from the scene. The Soviet "Photo Chronicle TASS" equipped the offices with a phototelegraph in 1957, and the photographs transferred to the central office in this way were signed by "Telephoto TASS". Technology dominated image delivery until the mid-1980s, when the first film scanners and video cameras appeared, followed by digital photography.

Wireless telegraph[ | ]

On May 7, 1895, at a meeting of the Russian Physicochemical Society, the Russian scientist Alexander Stepanovich Popov demonstrated a device, which he called a "lightning detector", which was designed to register radio waves generated by a thunderstorm front. This device is considered the first radio receiver in the world, suitable for the implementation of wireless telegraph. In 1897, using wireless telegraphy devices, Popov received and transmitted messages between the coast and a military ship. In 1899, Popov designed an improved version of the receiver of electromagnetic waves, where the reception of signals - ohm Morse - was carried out on the headphones of a radio operator. In 1900, thanks to radio stations built on the island of Gogland and at the Russian naval base in Kotka under the leadership of Popov, rescue operations were successfully carried out aboard the General-Admiral Apraksin warship, which ran aground off the island of Gogland. As a result of the exchange of radiotelegraph messages, the crew of the Russian icebreaker "Ermak" was promptly and accurately transmitted information about the Finnish fishermen who were on the ice floe in the Gulf of Finland.

Abroad, the technical thought in the field of wireless telegraphy also did not stand still. In 1896, the Italian Guglielmo Marconi filed a patent in Great Britain "on improvements made to the wireless telegraphy apparatus." The apparatus presented by Marconi, in general terms, repeated Popov's design, which had been described many times in European popular science journals by that time. In 1901, Marconi achieved a steady transmission of the wireless telegraph signal (letter S) across the Atlantic.

Bodo apparatus: a new stage in the development of telegraphy[ | ]

In 1872, the French inventor Jean Baudot designed a reusable telegraph apparatus that had the ability to transmit two or more messages in one direction over one wire. The Bodo apparatus and those created according to its principle were called start-stop. In addition, Bodo created a very successful telegraph (Bodo), which was subsequently perceived everywhere and received the name International Telegraph No. 1 (ITA1). The modified version of MTK No. 1 was named MTK No. 2 (ITA2). In the USSR, the telegraph MTK-2 was developed on the basis of ITA2. Further modifications of the design of the start-stop telegraph apparatus proposed by Baudot led to the creation of teleprinters (teletypes). In honor of Bodo, the unit of information transmission speed was named - baud.

Telex [ | ]

Siemens Telex T100

By 1930, the design of a start-stop telegraph apparatus was created, equipped with a disk-type telephone dialer (teletype). This type of telegraph apparatus, among other things, made it possible to personify the subscribers of the telegraph network and to quickly connect them. Almost simultaneously in Germany and Great Britain national subscriber telegraph networks were created, called Telex (TELEgraph + EXchange).

On the basis of international agreements of the 1930s, a telex message was recognized as a document, and a telex, respectively, as a type of documentary communication.

In Kazakhstan, telegraph services are not provided to individuals from January 1, 2018. For legal entities tariffs have been changed since July 1, 2018, now one word of a telegram costs 675 tenge (1.8 USD). The profitability of the provision of this service by the operator Kazaktelecom JSC amounted to minus 92 percent, which does not imply its further development.

At the same time, in Canada, Germany, Sweden, Japan, some companies still provide services for sending and delivering traditional telegraph messages.

Impact on society[ | ]

Telegraphy contributed to the growth of organization "on the railways, united financial and commodity markets, reduced the cost [of transmitting] information within and between enterprises." The growth of the business sector spurred society to further expand the use of the telegraph.

The introduction of telegraphy on a global scale has changed the approach to collecting information for news reporting. Messages and information now spread far and wide and the telegraph demanded the introduction of a language "free from local regional and non-literary aspects", which led to the development and standardization of the world media language.

see also [ | ]

Notes (edit) [ | ]

1. What was the first telegraph
2. Scan of the patent (unspecified) .
3. Phototelegraph- an article from the Great Soviet Encyclopedia.
4. L.Ya. Kraush. Phototelegram // Photocinema: Encyclopedia / Ch. ed. E. A. Iofis. - M.: Soviet Encyclopedia, 1981 .-- 447 p.
5. Michael Zhang.

In 1872, the French inventor Jean Baudot designed a reusable telegraph apparatus that had the ability to transmit two or more messages in one direction over one wire. The Bodo apparatus and those created according to its principle were called start-stop. In addition, Bodo created a very successful telegraph code (Bodo Code), which was subsequently adopted everywhere and received the name International Telegraph Code No. 1 (ITA1). The modified version of MTK No. 1 was named MTK No. 2 (ITA2). In the USSR, the telegraph code MTK-2 was developed on the basis of ITA2. Further modifications of the design of the start-stop telegraph apparatus proposed by Bodo led to the creation of teleprinters (teletypes). In honor of Bodo, the unit of information transmission speed was named - baud.

Siemens Telex T100

By 1930, the design of a start-stop telegraph apparatus was created, equipped with a disk-type telephone dialer (teletype). This type of telegraph apparatus, among other things, made it possible to personify the subscribers of the telegraph network and to carry out their fast connection. Almost simultaneously, in Germany and Great Britain, national telegraph networks were created, called Telex (TELEgraph + EXchange). A little later, the United States also created a national subscriber telegraphy network, similar to Telex, which was named TWX (Telegraph Wide area eXchange). International subscriber telegraphy networks were constantly expanding and by 1970 the Telex network united subscribers in more than 100 countries of the world. Only in the eighties, thanks to the appearance on the market of inexpensive and practical facsimile machines, the subscriber telegraph network began to lose ground in favor of facsimile communication.

The telegraph in the new century

Today, the messaging capabilities of the Telex network are largely due to e-mail... In Russia, telegraph communication still exists today, telegraph messages are transmitted and received using special devices - telegraph modems, coupled in electrical communication centers with personal computers of operators. Nevertheless, in some countries, national operators considered telegraph an obsolete form of communication and curtailed all operations for sending and delivering telegrams. In the Netherlands, telegraph services ceased operations in 2004. In January 2006, the oldest American national operator Western Union announced a complete cessation of services to the population for sending and delivering telegraph messages. At the same time, in Canada, Belgium, Germany, Sweden, Japan, some companies still support the service for sending and delivering traditional telegraph messages.

Telegraph communication has several varieties: telegraph communication that uses Morse code to encode information, teletype, deutephone and telex(fig. 5).

Rice. 5. Varieties of telegraph communication

Teletype communication

Teletype communication appeared later than telegraph, at the end of the 19th century, with the invention of direct-printing telegraph devices - teletype . Most teletypewriters have an alphanumeric keypad, printer, tape puncher, and punched tape reader.

Entering information into a teletypewriter can be carried out from the keyboard or from punched tape. The perforation of the tape (the application of codes on it in the form of holes located in a certain way) can be carried out on the teletype machine itself in advance, in offline... Since manual input of information from the keyboard does not provide a high transmission rate realized by the system, automated input is preferable. Teletype communication is still used in institutions and enterprises. But now the information transmitted to the teletype can be entered directly from a computer equipped with modem. During transmission, information is recorded by both the recipient and the sender on paper or punched tape.

Deutephone communication

In the presence of matching equipment (modem) as a communication channel for teletype equipment can serve not only the telegraph, but also the telephone channel. Transfer of documented text information over telephone channels are often called deutephone .

Teletypes can be connected either directly to each other or through a switch. Direct connection of teletype machines is advisable for organizing intra-company communication. When transmitting information over long distances, telegraph equipment is included in a single state system subscriber telegraphy. This network is used mainly by ministries, industrial enterprises, transport, financial institutions and military units.

Telex

To send messages to other countries, the international telegraph is used - telex. This network is widely used by commercial institutions, banks, stock exchanges, insurance companies, news agencies, private and public firms. The documents transmitted over these networks are legally binding, that is, they are recognized in all countries.

The Telex system has a computer version - Telex Net, which provides users with additional features... These include:

Work in local computer networks;

· dialogue;

· Automatic transfer of data from a computer;

A significant disadvantage of telegraph communication is the low reliability of information transmission. Therefore, when transmitting information via telegraphic communication channels, special measures are taken to increase the reliability.

In particular, the industry produces hardware equipped with error protection devices.

Now all types of telegraph communication are gradually being replaced fax .

Fax communication

The predecessor of facsimile communication was phototelegraph communication. It was used to transfer grayscale images.

The purpose of facsimile communication is the transmission of information over a distance in the form of texts, drawings, pictures, diagrams, photographs, etc. In essence, the facsimile method of transmitting information consists in remote copying of documents. Efficiency and ease of use are the indisputable advantages of fax.

Facsimile communication is based on the method of transmitting a sequence of electrical signals that characterize the brightness of the elements of the transmitted document. The transmitted image is decomposed into elements. The process of breaking down a document into elements is called scan, and viewing and reading these items is scanning.

For the organization of facsimile communication can be used telephone channels, as well as telegraph and radio communication channels. An important advantage of facsimile communication is complete automation of transmission. The speed and reliability of information transfer are quite high.

If the computer is equipped fax modem, the transmitted information can be entered into the computer's memory.

Currently manufactured facsimile machines differ in the way of image reproduction, resolution and other parameters.

V photographic fax machines, the document is printed from the receiving subscriber on photographic paper. The use of these devices is more expensive, but they transmit halftones better than others and have a high resolution (up to 10 dots per mm 2).

Electromechanical

thermographic thermal paper. electrographic and inkjet

laser

Documents are sent by fax in the following sequence:

Ø insert the document prepared for transmission face down into the fax receiving tray;

Ø press the SP-PHONE command or just pick up the handset;

Ø dial the subscriber's fax number;

Ø after the subscriber answers or, if the subscriber's fax is in automatic mode reception, having heard a specific beep signal, press the START button.

Ø Hang up if you have used it for negotiations.

Receiving messages by fax:

Ø Having heard the signal, pick up the receiver;

Ø Press the START button;

Ø After receiving the message, confirm the reception, hang up.

After sending a fax, many faxes send an automatic confirmation report that the message was sent and received as intended. In addition, you can always print a complete report of received and transmitted messages.

When faxing confidential documents, both your machine and the receiving machine must have identification codes to prevent unauthorized access and the receipt of classified information. If the codes of the sending and receiving machines do not match, the transmission will not take place.

Only the most basic telefax functions are described above. More complex and expensive faxes provide many additional functions such as:

· Delayed transmission, which allows, having prepared a document for transmission, send it at a specified time, for example, at night, when the tariffs for long-distance calls are much lower;

· Memory for several tens of pages, in which faxes are received, if the paper is taken out or ran out, followed by printing, you can load documents into the same memory for their subsequent sending at a specified time or sending them to several addressees;

· Reject unnecessary calls — ignore calls made from phones that are not in the speed dial memory.

For example, XEROX or CANON machines with a laser printing device, use ordinary paper, have all the possibilities described above, as well as many others. The memory holds 35 pages, expandable to 180 pages. The 250-sheet tray virtually eliminates the possibility of running out of paper, even with a large volume of incoming faxes. In addition, you can store in memory for deferred mailing of up to 20 different documents, each with its own mailing list.

If the fax does not work or is unstable, in some cases you can determine the cause of the problem and, possibly, fix the possible problems yourself:

· First of all, check if the POWER indicator is on. The fax may have been accidentally turned off or the power has gone out (some fax models will still hear a beep even if the power is disconnected);

· Check the status of the telephone line: try calling somewhere. If the phone doesn't work, then the fax won't work either;

· Ask the subscriber to dial your fax number and then “start”;

· Check if there is paper in the fax. When it ends, the NO PAPER (or PAPER OUT) indicator lights up.

Electromechanical fax machines are often referred to as line fax machines because they do not transmit halftones. They are distinguished by their simplicity of design and the use of plain paper. The resolution of these devices is within 4-6 points per mm 2.

Among modern facsimile machines, the most common are machines thermographic type. They are inexpensive, but have reasonably good performance (7-10 dots per mm 2, 20-40 gray levels). They use a special thermal paper . Roughly the same class includes electrographic and inkjet fax machines. Their important feature is the use of plain paper.

The most best performance have laser fax machines: up to 15 dots per mm 2, 64 gray levels, but these machines are still quite expensive.

Service capabilities of modern fax machines:

· Automatic feeding of documents and paper;

· Mode of copying documents;

· The ability to connect to a computer;

· Memorization of telephone numbers and text of the document, in case of absence or unexpected end of paper;

· Liquid crystal display showing operating modes;

· "Poling" mode (invitation of the desired station to send a message);

To expand the scope of services, facsimile service systems are being created. The system of the all-Russian extended fax service covers all the largest enterprises in more than 500 cities of Russia, the CIS countries and far abroad. This system provides its subscribers:

Access to the system from any fax machine or personal computer for sending documents;

· Delivery of documents immediately or with a delay;

· Confidentiality of transmitted information;

· Issuance of a receipt indicating the result of the subscriber's command (whether the document was delivered or not delivered), indicating the date and time, as well as the reason why the document was not delivered.

Abroad, facsimile systems are more developed than ours. Most hotels, airports, lobbies of many institutions and other public places have unattended booths with fax machines. They work on the same principle as payphones.

Telephone facsimile attachments are produced, which are used to transmit handwritten messages and handwritten schemes, signatures. Such a prefix is ​​an electronic notepad that is connected to the phone. When sending a fax, the subscriber writes or draws on a notepad with a special pen, the text or diagram is automatically encoded and sent to the receiving subscriber. It is important that the signature of the responsible person is transmitted in this way.

cellular

cellular- one of the types of mobile radio communications, which is based on cellular network. Key feature lies in the fact that the total coverage area is divided into cells (cells), which are determined by the coverage areas of individual base stations (BS). The honeycombs overlap partially and together form a network. On an ideal (even and without building) surface, the coverage area of ​​one BS is a circle, therefore, the network composed of them looks like honeycombs with hexagonal cells (honeycombs).

cellular	Cellular network
cellular	cellular

It is noteworthy that in the English version the communication is called "cellular" or "cellular" (cellular), which does not take into account the hexagonal nature of the honeycomb.

The network consists of spaced-apart transceivers operating in the same frequency range, and switching equipment that allows determining the current location of mobile subscribers and ensuring continuity of communication when a subscriber moves from the coverage area of ​​one transceiver to the coverage area of ​​another.

The first use of mobile telephony in the United States dates back to 1921: Detroit police used one-way dispatch in the 2 MHz band to transmit information from a central transmitter to vehicle-mounted receivers. In 1933, the New York police began using a two-way mobile telephone radio system, also in the 2 MHz band. In 1934, the US Federal Communications Commission allocated 4 channels for telephone radio communications in the range of 30 ... 40 MHz, and in 1940, about 10 thousand police vehicles were already using telephone radio communications. All of these systems used amplitude modulation. Frequency modulation began to be used in 1940 and by 1946 completely replaced amplitude modulation. The first public mobile radiotelephone appeared in 1946 (St. Louis, USA; Bell Telephone Laboratories) using the 150 MHz band. In 1955, an 11-channel system began operating in the 150 MHz range, and in 1956 - a 12-channel system in the 450 MHz range. Both of these systems were simplex and used manual switching. Automatic duplex systems began operating in 1964 (150 MHz) and 1969 (450 MHz), respectively.

In the USSR In 1957, a Moscow engineer L. I. Kupriyanovich created a prototype of a portable automatic duplex mobile radiotelephone LK-1 and a base station for it. The mobile radiotelephone weighed about three kilograms and had a range of 20-30 km. In 1958, Kupriyanovich created improved models of the apparatus weighing 0.5 kg and the size of a cigarette box. In the 60s Hristo Bochvarov in Bulgaria demonstrates his prototype of a pocket mobile radiotelephone. At the exhibition "Interorgtechnika-66" Bulgaria presents a kit for organizing local mobile communications from pocket mobile phones RAT-0.5 and ATRT-0.5 and RATTs-10 base station, providing connection of 10 subscribers.

At the end of the 50s, the development of the Altai automobile radiotelephone system began in the USSR, which was put into trial operation in 1963. The Altai system initially operated at a frequency of 150 MHz. In 1970 the Altai system operated in 30 cities of the USSR and a 330 MHz band was allocated for it.

Similarly, with natural differences and on a smaller scale, the situation has developed in other countries. Thus, in Norway, public telephone radio communications have been used as maritime mobile communications since 1931; in 1955 there were 27 coastal radio stations in the country. Ground mobile connection began to develop after the Second World War in the form of private hand-switched networks. Thus, by 1970, mobile telephone radio communication, on the one hand, had already become quite widespread, but on the other hand, it clearly did not keep up with the rapidly growing needs, with a limited number of channels in strictly defined frequency bands. A solution was found in the form of a cellular communication system, which made it possible to dramatically increase capacity by reusing frequencies in a cellular system.

Of course, as is usually the case in life, individual elements cellular communication systems have existed before. In particular, some similarity cellular system was used in 1949 in Detroit (USA) by a taxi dispatching service - with re-use of frequencies in different cells with manual channel switching by users at predetermined locations. However, the architecture of the system that is today known as the cellular communication system was only outlined in the Bell System technical report submitted to the US Federal Communications Commission in December 1971. And from that time the development of cellular communication itself begins, which has become truly triumphant since 1985. g., in the last ten years and a little.

In 1974, the FCC decided to allocate a 40 MHz frequency band for cellular communications in the 800 MHz range; in 1986, another 10 MHz was added to it in the same range. In 1978, tests of the first prototype cellular communication system for 2,000 subscribers began in Chicago. Therefore, 1978 can be considered the year of the beginning of the practical application of cellular communications. The first automatic commercial cellular system was also commissioned in Chicago in October 1983 by American Telephone and Telegraph (AT&T). In Canada cellular used since 1978, in Japan - since 1979, in Scandinavian countries (Denmark, Norway, Sweden, Finland) - since 1981, in Spain and England - since 1982. As of July 1997 cellular communication has worked in more than 140 countries of all continents, serving more than 150 million subscribers.

The first commercially successful cellular network was the Finnish network Autoradiopuhelin (ARP). This name is translated into Russian as "Car radiotelephone". Launched in 1971, it reached 100% coverage of the Finnish territory in 1978. The cell size was about 30 km, in 1986 it had more than 30 thousand subscribers. She worked at a frequency of 150 MHz.

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The telegraph is, the definition

The telegraph is a means of transmitting a signal over wires or other telecommunication channels.

The telegraph is a system of technical devices for transmitting messages over a distance over wires using.

The telegraph is a means of transmitting signals over wires, radio or other communication channels.

The telegraph is a device for transmitting any signals (for example letters) over a distance using electricity through wires.

The telegraph is an institution, a building in which notifications sent in this way are accepted for sending and received.

The telegraph is a communication system that provides fast transmission of messages over a distance - by means of electrical signals over wires or by radio - with their recording at the receiving point.

Bodo apparatus - a new stage in the development of telegraphy

In 1872, the French inventor Jean Baudot designed a reusable telegraph apparatus that had the ability to transmit two or more messages in one direction over one wire. The Bodo apparatus and those created according to its principle were called start-stop. In addition, Bodo created a very successful telegraph code (Bodo Code), which was subsequently adopted everywhere and received the name International Telegraph Code No. 1 (ITA1). The modified version of MTK No. 1 was named MTK No. 2 (ITA2). In the USSR, the telegraph code MTK-2 was developed on the basis of ITA2. Further modifications of the design of the start-stop telegraph apparatus proposed by Baudot led to the creation of teleprinters (teletypes). In honor of Bodo, the unit of information transmission speed was named - baud.

Telex

By 1930, the design of a start-stop telegraph apparatus was created, equipped with a disk-type telephone dialer (teletype). This type of telegraph apparatus, among other things, made it possible to personify the subscribers of the telegraph network and to quickly connect them. Almost simultaneously in the UK, national subscriber telegraph networks were created, called Telex (Telegraph + EXchange).

Sources and links

Sources of text, pictures and videos

ru.wikipedia.org

scsiexplorer.com.ua