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Wireless telegraphy is a historical term today that applies to early radio telegraph communication technique and practice, particularly those used during the first three decades of radio (1887 to 1920) before the term radio came into use.
Wireless telegraphy originated as a term to describe electrical signaling without wires to connect the endpoints. The intent was to distinguish it from conventional telegraph signaling of the day that required a wired connection between the points. The term was initially applied to a variety of competing technologies to communicate messages encoded as symbols, without wires, around the turn of the 20th century, but radio emerged as the most significant.
Wireless telegraphy rapidly came to mean Morse code transmitted with Hertzian waves (electromagnetic waves) decades before it came to be associated with the term radio. Radiotelephony by 1920s began to displace radio telegraphy for many applications and was the basis of public broadcasting. Radiotelegraphy continued to be used for point-to-point business, governmental, and military communication, and evolved into radioteletype networks. Wireless telegraphy is still used widely today by amateur radio hobbyists where it is commonly referred to as radiotelegraphy, continuous wave, or just CW.
History of Development
Wireless detailed history and growth of the art includes the work of Nikola Tesla, Oliver Lodge, Marconi, Braun, Reginald Fessenden (known for inventing the radiotelephony), John Ambrose Fleming, Lee De Forest and many others.
Prior technologies other than radio
Ground and water conduction
Historically, "wireless" technologies have ranged from smoke signals and talking drums to the heliograph, semaphore line, and flag semaphore. Maritime flags and signal lamps are still in use. A number of wireless electrical signaling schemes including electrical currents through water and dirt were investigated for telegraphy before practical radio systems became available.
The original telegraph used two wires between two stations to form a complete electrical circuit or "loop". In 1837 however, Carl August von Steinheil of Munich, Germany found that by connecting one leg of the apparatus at each station to metal plates buried in the ground, he could eliminate one wire and use a single wire for telegraphic communication. This led to speculation that it might be possible to eliminate both wires, and transmit telegraph signals through the ground without any wires connecting the stations. Other attempts were made to send the electric current through bodies of water, in order to span rivers, for example. Prominent experimenters along these lines included Samuel F. B. Morse in the United States and James Bowman Lindsay in Great Britain.
Telegraphic communication using earth conductivity was eventually found to be limited to impractically short distances, as was communication conducted through water, or between trenches during World War I.
Electrostatics and electromagnetics
Both electrostatic and electromagnetic induction were used to develop wireless telegraph systems which saw limited commercial application. In the United States, Thomas Edison, in the mid-1880s, patented an electromagnetic induction system he called "grasshopper telegraphy", which allowed telegraphic signals to jump the short distance between a running train and telegraph wires running parallel to the tracks. This system was successful technically but not economically, as there turned out to be little interest by train travelers in an on-board telegraph service. (U.S. Patent 465,971, Means for Transmitting Signals Electrically, 1891). During the Great Blizzard of 1888, this system was used to send and receive wireless messages from trains buried in snowdrifts, perhaps the first successful use of wireless telegraphy to send distress calls. The disabled trains were able to maintain communications via their Edison induction wireless telegraph systems.
The most successful creator of an electromagnetic induction telegraph system was William Preece in Great Britain. Beginning with tests across the Bristol Channel in 1892, Preece was able to telegraph across gaps of about five kilometers. However, his induction system required extensive lengths of antenna wires, many kilometers long, at both the sending and receiving ends. The length of those sending and receiving wires needed to be about the same length as the width of the water (or land) that needed to be spanned. For example, for Preece's station to span the English Channel from Dover, England, to the coast of France would require sending and receiving wires of about 30 miles (48 kilometres) along the two coasts. These facts made it impractical to use Preece's system on either ships, boats, or ordinary islands (ones much smaller than Great Britain or Greenland), and the relatively short distances that a practical Preece system could span meant that it had few advantages over underwater telegraph cables.
Period before 1838
In 1832, Lindsay gave a classroom demonstration of wireless telegraphy to his students. By 1854 he was able to demonstrate transmission across the Firth of Tay from Dundee to Woodhaven (now part of Newport-on-Tay), a distance of two miles (three kilometers).
Wireless telegraphy dates as far back as Faraday in the early 19th century, when it was discovered that radio waves could be used to send telegraph messages. After James Clerk Maxwell had predicted the existence of electromagnetic waves, and had shown that their speed of propagation is identical with that of light, it required, in reality, very little to demonstrate by experiment the existence of such waves.
By 1884, Temistocle Calzecchi-Onesti at Fermo in Italy developed a primitive device that responded to radio waves. It consisted of a tube filled with iron filings, called a "coherer". This kind of device would later be developed to become the first practical radio detector. Writing in the Rendiconti of the Lombardy Institution regarding the discovery of the coherer, directs attention to his experiments made in 1884, before Branly had worked on the subject. He further points out the part played by Augusto Righi in wireless telegraphy.
Calzecchi found that the conductivity of metal powder varied depending on the incidence of radio waves. Calzecchi's experiments were not widely reported. He would later write, Le mie esperienze e di Edoardo quelle Branly Sulla conduttività elettrica delle limature metalliche.
Between 1886 and 1888, Heinrich Rudolf Hertz studied Maxwell's theory and validated it through experiment. He demonstrated the transmission and reception of the electromagnetic waves predicted by Maxwell and intentionally transmitted and received radio. Hertz changed the frequency of his radiated waves by altering the inductance or capacity of his radiating conductor or antenna, and reflected and focused the electromagnetic waves, thus demonstrating the correctness of Maxwell's electromagnetic theory of light. Famously, he saw no practical use for his discovery.
In his UHF experiments, he transmitted and received radio waves over short distances and showed that the properties of radio waves were consistent with Maxwell’s electromagnetic theory. He demonstrated that radio radiation had all the properties of waves (now called electromagnetic radiation), and discovered that the electromagnetic equations could be reformulated into a partial differential equation called the wave equation.
Heinrich Hertz (1888) demonstrated the existence of electromagnetic radiation (radio waves) in a series of experiments in Germany during the 1880s. Hertz showed methods of producing, detecting, and measuring these waves. It had been known for many years, from the predictions of Kelvin and Von Helmholtz, and confirmed by the experiments of Fedderssen, that in many cases an electric discharge is of an oscillatory character. In the years 1887-8, Lodge, Fitzgerald, and others were investigating the nature of these oscillations, and the manner in which they are guided by conducting wires, when Hertz conceived the idea of investigating the disturbances which such oscillatory discharges set up in the surrounding space.
Hertz used the damped oscillating currents in a dipole antenna, triggered by a high-voltage electrical capacitive spark discharge, as his source of radio waves. His detector in some experiments was another dipole antenna connected to a narrow spark gap. A small spark in this gap signified detection of the radio waves. When he added cylindrical reflectors behind his dipole antennas, Hertz could detect radio waves about 20 metres from the transmitter in his laboratory. He did not try to transmit further because he wanted to prove electromagnetic theory, not to develop wireless communications.
In the collection of physical instruments at the Technical High School at Karlsruhe (where these researches were carried out), Hertz had found and used for lecture purposes a pair of so-called Eiess spirals or Knochenhauer spirals. Hertz had been surprised to find that it was not necessary to discharge large batteries through one of these spirals in order to obtain sparks in the other; that small Leyden jars amply sufficed for this purpose, and that even the discharge of a small induction coil would do, provided it had to spring across a spark gap. In altering the conditions Hertz came upon the phenomenon of side-sparks, which formed the starting point of his research. At first Hertz thought the electrical disturbances would be too turbulent and irregular to be of any further use, but when he had discovered the existence of a neutral point in the middle of a side-conductor, and therefore of a clear and orderly phenomenon, he felt convinced that the problem of the Berlin Academy was now capable of solution. His ambition at the time did not go further than this. Hertz's conviction was naturally strengthened by finding that the oscillations with which he had to deal were regular.
Hertz’s setup for a source and detector of radio waves (then called Hertzian waves in his honor) was the first intentional and unequivocal transmission and reception of radio waves through free space. The first of the papers published ("On Very Rapid Electric Oscillations") gives, generally in the actual order of time, the course of the investigation as far as it was carried out up to the end of the year 1886 and the beginning of 1887.
Hertz, though, did not devise a system for actual general use nor describe the application of the technology and seemed uninterested in the practical importance of his experiments. He stated that "It's of no use whatsoever ... this is just an experiment that proves Maestro Maxwell was right — we just have these mysterious electromagnetic waves that we cannot see with the naked eye. But they are there."
Asked about the ramifications of his discoveries, Hertz replied, "Nothing, I guess." Hertz also stated, "I do not think that the wireless waves I have discovered will have any practical application." Hertz died in 1894, so the art of radio was left to others to implement into a practical form.
In 1890, Édouard Branly demonstrated what he later called the "radio-conductor," which Lodge in 1893 named the coherer, the first sensitive device for detecting radio waves. Shortly after the experiments of Hertz, Dr. Branly discovered that loose metal filings, which in a normal state have a high electrical resistance, lose this resistance in the presence of electric oscillations and become conductors of electricity. This Branly showed by placing metal filings in a glass box or tube and making them part of an ordinary electric circuit. According to the common explanation, when electric waves are set up in the neighborhood of this circuit, electromotive forces are generated in it which appear to make the filings move closer together, that is, to cohere, and thus their electrical resistance decreases accordingly, Sir Oliver Lodge termed this piece of apparatus a coherer. Hence the receiving instrument, which may be a telegraph relay, that normally would not indicate any sign of current from the small battery, can be operated when electric oscillations are set up. Prof. Branly further found that when the filings had once cohered, they retained their low resistance until shaken apart, for instance, by tapping on the tube.
In On the Changes in Resistance of Bodies under Different Electrical Conditions, he described how the electrical circuit was made by means of two narrow strips of copper parallel to the short sides of the rectangular plate, and forming good contact with it by means of screws. When the two copper strips were raised, the plate was cut out of the circuit. He also used as conductors fine metallic filings, which he sometimes mixed with insulating liquids. The filings were placed in a tube of glass or ebonite and were held between two metal plates. When the electrical circuit, consisting of a Daniell cell, a galvanometer of high resistance, and the metallic conductor, consisting of the ebonite plate, and the sheet of copper, or of the tube containing the filings, was completed, only a very small current flowed; but there was a sudden diminution of the resistance, which was proved by a large deviation of the galvanometer needle when one or more electric discharges were produced in the neighbourhood of the circuit. In order to produce these discharges, a small Wimshurst influence machine was used, with or without a condenser, or a Ruhmkorff coil. The action of the electrical discharge diminished as the distance increases; but Branley observed it easily, and without taking any special precautions, at a distance of several yards. By using a Wheatstone bridge, he observed this action at a distance of 20 yards, although the machine producing the sparks was working in a room separated from the galvanometer and the bridge by three large apartments, and the noise of the sparks was not audible. The changes of resistance were considerable with the conductors described. They varied, for instance, from several millions of ohms to 2000, or even to 100, from 150,000 to 500 ohms, from 50 to 35, and so on. The diminution of resistance was not momentary, and sometimes it was found to remain for 24 hours. Another method of making the test was by connecting the electrodes of a capillary electrometer to the two poles of a Daniell cell with a sulphate of cadmium solution. The displacement of mercury which took place when the cell was short-circuited, only took place very slowly when an ebonite plate, covered with a sheet of copper of high resistance, was inserted between one of the poles of the cell, and the corresponding electrode of the electrometer; but when sparks were produced by a machine, the mercury was rapidly thrown into the capillary tube owing to the sudden diminution in the resistance of the plate.
Upon examination of the conditions necessary to produce the phenomena, Branly found that:
- The circuit need not be closed to produce the result.
- The passage of an induced current in the body produces a similar effect to that of a spark at a distance.
- An induction coil with two equal lengths of wire was used, a current is sent through the primary while the secondary forms part of a circuit containing the tube with filings and a galvanometer. The two induced currents caused the resistance of the filings to vary.
- When working with continuous currents, the passage of a strong current lowers the resistance of the body for feeble currents.
Summing up, he stated that in all these tests, the use of ebonite plates covered with copper or mixtures of copper and tin was less satisfactory than the use of filings; with the plates, he was unable to obtain the initial resistance of the body after the action of the spark or of the current, while with the tubes and filings, the resistance could be brought back to its normal value by striking a few sharp blows on the support of the tube.
The disadvantages of the coherer are its erratic sensitivity, which may be much decreased by local discharges, such as the spark discharges of the transmitter, and its response to atmospheric disturbances or lightning discharges. Consequently, the coherer cannot be relied upon as a calling-up apparatus. With strong impulses of energy in the receiver, it enables one to print the received message, but for long-distance work, it is not as sensitive as some other detectors that were developed in the inter-war period before the roaring Twenties.
Landell de Moura
Roberto Landell de Moura, a Brazilian priest and scientist, went to Rome in 1878 and studied at the South American College and Pontifical Gregorian University, where he studied physics and chemistry. He completed his clerical training in Rome, graduating in theology, and was ordained priest in 1886. In Rome, he started studying physics and electricity. When he returned to Brazil, he conducted experiments in wireless in Campinas and São Paulo (1892–1893). In the "Porto Jornal da Manha", he is said to have conducted between 1890 and 1894 wireless transmissions in telegraphy and telephony over distances of up to 8 kilometres (5.0 mi).
In St. Louis, Missouri, Nikola Tesla made the first public demonstration of a modern wireless system in 1893. Addressing the Franklin Institute in Philadelphia and the National Electric Light Association, he described and demonstrated in detail the principles of wireless telegraphy and radio. The apparatus that he used contained all the elements that were incorporated into radio systems before the development of the vacuum tube. This led to work in using radio signals for wireless communication, initially with limited success. Using spark-gap transmitters plus coherer-receivers were tried by many experimenters, but several were unable to achieve transmission ranges of more than a few hundred metres. This was not the case for all researchers in the field of the wireless arts, though.
In 1891, Nikola Tesla began his research into radio. Around July 1891, Tesla developed various alternator apparatuses that produced 15,000 cycles per second. In 1892 he gave a lecture called "Experiments with Alternate Currents of High Potential and High Frequency". Tesla delivered the presentation before the Institution of Electrical Engineers of London (February 3, 1892) in which he suggested that messages could be transmitted without wires. He repeated this to the Royal Institution (February 4, 1892). He would again repeat the presentation to the Société Française de Physique (February 19, 1892) in Paris. Tesla realized he gained, by the use of very high frequencies, many advantages in his experiments, such as the possibility of working with one lead and the possibility of doing away with the leading-in wire. In transmitting impulses through conductors, he dealt with high pressure and high flow, in the ordinary interpretation of these terms. Towards the end of the lecture, he proposed that sending over the wire current vibrations of very high frequencies at enormous distance without affecting greatly the character of the vibrations and that telephony could be rendered practicable across the Atlantic. He also proposed that intelligence — transmitted without wires — transmission through the Earth and to establish the physical mechanism of such a circuit. Tesla captured the attention of the whole scientific world by his fascinating experiments on high frequency electric currents. He stimulated the scientific imagination of others as well as displayed his own, and created a widespread interest in his brilliant demonstrations.
There are seven elements in the complete oscillation-producing appliance, which are as follows:
- The induction coil transformer or source of electromotive force.
- The condenser.
- The discharger or spark balls.
- The arc quenching inductances.
- The oscillation transformer.
- The adjustable inductance for varying the period.
- The controller or key in the primary circuit of the coil or transformer.
These several elements have each to be considered separately with reference to their best practical forms for various purposes. When the key is closed, and the apparatus in operation, there are trains of intermittent electrical oscillations set up in the circuit, and if the terminals of the secondary circuit of the oscillation transformer are near together, there is high potential high frequency oscillatory sparks passing between them. The above-described apparatus in a typical form is generally called a Tesla apparatus for the production of high frequency electric currents.
"On Light and Other High Frequency Phenomena"
In 1893, at St. Louis, Missouri, Tesla gave a public demonstration, "On Light and Other High Frequency Phenomena", of wireless communication. Addressing the Franklin Institute in Philadelphia, he described in detail the principles of early radio communication. The lecture apparatus that Tesla used contained all the elements that were incorporated into radio systems before the development of the "oscillation valve", the early vacuum tube. The lecture delivered before the Franklin Institute, at Philadelphia, occurred on February 24, 1893. The variety of Tesla's radio frequency systems were again demonstrated during when he presented to meetings of the National Electric Light Association, at St. Louis, on March I, 1893. Afterward, the principle of radio communication (sending signals through space to receivers) was publicized widely from Tesla's experiments and demonstrations. On August 25, 1893, Tesla delivered the lecture "Mechanical and Electrical Oscillators", before the International Electrical Congress, in the hall adjoining the Agricultural Building, at the World's Fair, Chicago. This helped popularize radio communication activity worldwide, which is covered in depth by Invention of Radio and History of Radio.
The high-frequency phenomena which Tesla first developed and displayed had scientific rather than practical interest; but Tesla called attention to the fact that by taking the Tesla oscillator, grounding one side of it and connecting the other to an insulated body of large surface, it should be possible to transmit electric oscillations to a great distance, and to communicate intelligence in this way to other oscillators in sympathetic resonance therewith. This was going far toward the invention of radio-telegraphy as then known.
Transmission and radiation of radio frequency energy was a feature exhibited in the experiments by Tesla which he proposed might be used for the telecommunication of information. The Tesla method was described in New York in 1897.
In 1894, T. C. Martin published "The Inventions, Researches and Writings of Nikola Tesla", detailing the work of Tesla in the previous years. Various scientists, inventors, and experimenters began to investigate wireless methods. Tesla's work contained coupled oscillation circuits having capacity and inductance in series. In 1897, Tesla applied for two key United States radio patents, US 645576 , the first radio system patent, and US 649621 . Tesla also used sensitive electromagnetic receivers, that were unlike the less responsive coherers later used by Marconi and other early experimenters. Shortly thereafter, he began to develop wireless remote control devices.
By 1897, Guglielmo Marconi conducted a series of demonstrations with a radio system for signalling for communications over long distances. Marconi is said to have read, while on vacation in 1894, about the experiments that Hertz did in the 1880s. Marconi also read about Tesla's work. It was at this time that Marconi began to understand that radio waves could be used for wireless communications. Marconi's early apparatus was a development of Hertz’s laboratory apparatus into a system designed for communications purposes. At first, Marconi used a transmitter to ring a bell in a receiver in his attic laboratory. He then moved his experiments out-of-doors on the family estate near Bologna, Italy, to communicate farther. He replaced Hertz’s vertical dipole with a vertical wire topped by a metal sheet, with an opposing terminal connected to the ground. On the receiver side, Marconi replaced the spark gap with a metal powder coherer, a detector developed by Edouard Branly and other experimenters. Marconi transmitted radio signals for about a mile at the end of 1895.
By 1896, Marconi introduced to the public a device in London, asserting it was his invention. Despite Marconi's statements to the contrary, though, the apparatus resembles Tesla's descriptions in his research, demonstrations and patents. Marconi's later practical four-tuned system was pre-dated by N. Tesla, Oliver Lodge, and J. S. Stone. He filed a patent on his earliest system with the British Patent Office on June 2, 1896.
In 1897, Marconi was awarded a patent for radio with British patent No. 12,039, Improvements in Transmitting Electrical Impulses and Signals and in Apparatus There-for. The complete specification was filed March 2, 1897. This was Marconi's initial patent for the radio, though it used various earlier techniques of various other experimenters (primarily Tesla) and resembled the instrument demonstrated by others (including Popov). During this time, spark-gap wireless telegraphy was widely researched. In July, 1896, Marconi got his invention and new method of telegraphy to the attention of Preece, then engineer-in-chief to the British Government Telegraph Service, who had for the previous twelve years interested himself in the development of wireless telegraphy by the inductive-conductive method. On June 4, 1897, Preece delivered his lecture, "Signalling through Space without Wires". Preece devoted considerable time to exhibiting and explaining the Marconi apparatus at the Royal Institution in London, stating that Marconi had invented a new relay which had high sensitivity and delicacy.
In 1896, Jagdish Chandra Bose went to London on a lecture tour and met Marconi, who was conducting wireless experiments for the British post office. In 1897, Marconi founded the Marconi Company Ltd.. Also in 1897, Marconi established the radio station at Niton, Isle of Wight, England. Marconi's wireless telegraphy was inspected by the Post Office telegraph authorities; they made a series of experiments with Marconi's system in the Bristol Channel. In October 1897, wireless signals were sent from Salisbury Plain to Bath, a distance of 34 miles. Marconi's reputation is largely based on the formulation of Marconi's law (1897), and other accomplishments in radio communications and commercializing a practical system.
Other experimental stations were established at Lavernock Point, near Penarth; on Flat Holm, off Cardiff in the Bristol Channel, and at Brean Down, a promontory on the Somerset side. Signals were obtained between the first and last-named points, a distance of approximately eight miles. The receiving instrument used was a Morse inkwriter of the Post Office pattern.
The term wireless telegraphy came into widespread use around the turn of the 19th century, when spark-gap transmitters and primitive receivers made it practical to send telegraph messages over great distances, enabling transcontinental and ship-to-shore signalling. Before that time, wireless telegraphy was an obscure experimental term that applied collectively to an assortment of sometimes unrelated signalling schemes. In 1898, Tesla demonstrated a radio-controlled boat in Madison Square Garden that allowed secure communication between transmitter and receiver.
In 1899, Landell de Moura transmitted the human voice from the College of the Sisters of St. Joseph, high in the district of Santana, Brazil, north of the capital city. He also publicly demonstrated his invention on June 3, 1900. As the Jornal do Commercio reported (June 10, 1900), "Last Sunday, on top of Santana in São Paulo, Padre Landell de Moura has particular experience with various devices of his invention. In order to demonstrate some laws which he discovered in studying the propagation of sound, the light and electricity through space, which were crowned with brilliant success." The experiments were performed in the presence of the English Vice Consul S. Paul, Percy Parmenter, Charles Lupton, and other persons of high social position. Upon observing the experiments, Rodriguez Botet, giving news of the trials, said he was not far from the moment of consecrating Landell de Moura as an author of radio discoveries. Landell de Moura later received several patents on wireless technology. He would later obtain U.S. Patent 775,337 for a wireless telephone.
In 1898, Marconi opened a radio factory in Hall Street, Chelmsford, England, employing around 50 people. In 1899, Marconi announced his invention of the "iron-mercury-iron coherer with telephone detector" in a paper presented at the Royal Society, London. In May, 1898, communication was established for Lloyd's of London between Ballycastle and the lighthouse on Rathlin Island in the North of Ireland. In July, 1898, the Marconi telegraph was employed to report the results of yacht races at the Kingston Regatta for the Dublin Express newspaper. One set of instruments was set up in a room at Kingstown, and another on board a steamer, the Flying Huntress. The aerial conductor on shore was a strip of wire netting attached to a mast 40 feet high. Several hundred messages were sent and correctly received during the progress of the races.
At this time King Edward VII, then Prince of Wales, had the misfortune to injure his knee and was confined on board the royal yacht Osborne in Cowes Bay. Marconi fitted up his apparatus on board the royal yacht by request, and also at Osborne House, Isle of Wight, and kept up wireless communication for three weeks between these stations. The distances covered were small; but as the yacht moved about, on some occasions high hills were interposed, so that the aerial wires were overtopped by hundreds of feet, yet this was no obstacle to communication. These demonstrations led the Corporation of Trinity House to afford an opportunity for testing the system in practice between the South Foreland Lighthouse, near Dover, and the East Goodwin Lightship, on the Goodwin Sands. This installation was set in operation on December 24, 1898, and proved to be of value. It was shown that when once the apparatus was set up, it could be worked by ordinary seamen with very little training.
At the end of 1898 electric wave telegraphy established by Marconi had demonstrated its utility, especially for communication between ship and ship and ship and shore. The Haven Hotel station and Wireless Telegraph Mast was where much of Marconi's research work on wireless telegraphy was carried out after 1898. In 1899, W. H. Preece delivered a lecture on "Aetheric Telegraphy", stating that the experimental stage in wireless telegraphy had been passed in 1894 and inventors were then entering the commercial stage. Preece, continuing in the lecture, detailed the work of Marconi and other British inventors. The Marconi Company was renamed the Wireless Telegraph Trading Signal Company in 1900. In 1899 he transmitted messages across the English Channel. The British Navy experiments with Marconi's system in the Anglo-Boer War from 1899-1902 were the first use of operational wireless telegraphy in the field.
In 1901, Marconi claimed to have received daytime transatlantic radio frequency signals at a wavelength of 366 metres (820 kHz). Marconi established a wireless transmitting station at Marconi House, Rosslare Strand, Co. Wexford in 1901 to act as a link between Poldhu in Cornwall and Clifden in Co. Galway. His announcement on 12 December 1901 stated that signals transmitted by the company's new high-power station at Poldhu, Cornwall were received at Signal Hill in St John's, Newfoundland (now part of Canada), using a 152.4-metre (500 ft) kite-supported antenna for reception. The message received was the Morse letter 'S' - three dots. This has recently been contested, however, based on theoretical work as well as a reenactment of the experiment; it is possible that Marconi heard only random atmospheric noise, which was mistaken for a signal, or that he heard a shortwave harmonic of the signal. The distance between the two points was about 3,500 kilometres (2,200 mi).
Marconi transmitted from England to Canada and the United States. In 1902, a Marconi station was established in the village of Crookhaven, County Cork, Ireland to provide marine radio communications to ships arriving from the Americas. A ship's master could contact shipping line agents ashore to enquire which port was to receive their cargo without the need to come ashore at what was the first port of landfall. Ireland was also, due to its western location, to play a key role in early efforts to send trans-Atlantic messages. Marconi transmitted from his station in Glace Bay, Nova Scotia, Canada across the Atlantic, and on 18 January 1903 a Marconi station sent a message of greetings from Theodore Roosevelt, the President of the United States, to the King of the United Kingdom, marking the first transatlantic radio transmission originating in the United States.
Period After 1902
In the early 20th century Jozef Murgas, the "Radio Priest", conducted a great deal of revolutionary work in wireless telegraphy. He established a laboratory in Wilkes-Barre, in which he primarily investigated radiotelegraphy. His article in the Tovaryšstvo magazine of 1900 shows that his radiotelegraphy studies had achieved a high level. In 1904, he received his first two US patents: the Apparatus for wireless telegraphy and The way of transmitted messages by wireless telegraphy. Another 11 patents followed between 1907 and 1911. Based on the first two patents, he created the Universal Ether Telegraph Co., which organized a public test of Murgaš's transmitting and receiving facilities in September 1905. The test was successful, but a storm destroyed the antenna masts three months later, which led to the dissolution of the company.
In 1906, Lee De Forest brought out a vacuum tube device which he called the "audion". This was a very sensitive detector of electric oscillations. It consisted of three electrodes in a vacuum tube; one of the electrodes could be heated to incandescence with the result that it emitted electrons (the Edison effect).
When the United States entered World War I, private radiotelegraphy stations were prohibited, which put an end to several pioneers' work in this field. By the 1920s, there was a worldwide network of commercial and government radiotelegraphic stations, plus extensive use of radiotelegraphy by ships for both commercial purposes and passenger messages. The ultimate implementation of wireless telegraphy was telex, using radio signals, which was developed in the 1930s and was for many years the only reliable form of communication between many distant countries. The most advanced standard, CCITT R.44, automated both routing and encoding of messages by short wave transmissions. (See telegraphy for more information).
Methods, apparatus, and operation
|This section requires expansion. (December 2010)|
In De Forest method. a battery connected between this electrode, as cathode, and another as anode resulted in a convection current of electrons from one to the other. Since negative electricity only was present, current could flow in but one direction. This is so far the action of the Fleming valve which also makes use of the Edison effect, but in the audion an epoch making advance was made in that the third electrode allows us to completely control the strength of the electron current without consuming appreciable energy at that electrode or in its circuit. In other words an inappreciable amount of power applied to the third electrode, or grid, will result in large changes in power in the anode circuit. Moreover, since the electrons have no appreciable inertia, the response in the anode circuit to stimuli in the grid circuit is practically instantaneous.
German troops erecting a wireless field telegraph station during World War I
- AT&T Corporation originally American Telephone and Telegraph Company
- Electrical telegraph
- Imperial Wireless Chain
References and notes
- American Institute of Electrical Engineers. (1908). "Wireless Telephony — By R. A. Fessenden (Illustrated.)", Transactions of the American Institute of Electrical Engineers. New York: American Institute of Electrical Engineers.
- "Defied the storm's worst-communication always kept up by 'train telegraphy,'" New York Times, March 17, 1888, page 8. Proquest Historical Newspapers (subscription). Retrieved February 6, 2008
- Fahie, J. J., A History of Wireless Telegraphy, 1838-1899, 1899, p. 29
- Tapan K. Sarkar, History of wireless. Page 262.
- xxxix., 14
- Nature, Volume 75 edited by Sir Norman Lockyer. Page 158.
- Bulletin By Société française des électriciens, Société internationale des électriciens. Pg 19-20
- RendicontidelR. Ist. Lomb, di te, e lett., Series II, Vol. XLIV. 1911.
- tr., "My experiences and those of Edward Branly The electrical conductivity of metal filings".
- Hertz, H. (1893). Electric waves: Being researches on the propagation of electric action with finite velocity through space. Dover Publications.
- Massie, W. W., & Underhill, C. R. (1911). Wireless telegraphy and telephony popularly explained. New York: D. Van Nostrand.
- Transactions, Volume 27, Part 1 By American Institute of Electrical Engineers
- Further information can be found at, Spark-gap transmitter.
- Electric waves; being research on the propagation of electric action with finite velocity through space by Heinrich Rudolph Hertz, Daniel Evan Jones 1 Review Macmillan and co., 1893. Pages1 - 5
- "Hertzian Waves (1901)". Retrieved 2008-08-11.
- "Hertz wave". Tfcbooks.com. Retrieved 2010-01-31.
- Eugenii Katz, "Heinrich Rudolf Hertz". Biographies of Famous Electrochemists and Physicists Contributed to Understanding of Electricity, Biosensors & Bioelectronics.
- Variations of Conductivity under Electrical Influences, By Edouard Branly. Minutes of proceedings of the Institution of Civil Engineers, Volume 103 By Institution of Civil Engineers (Great Britain) Page 481 (Contained in, Comptes rendus de I'Acade'mie des Sciences, Paris, vol. cii., 1890, p. 78.)
- On the Changes in Resistance of Bodies under Different Electrical Conditions. By E. Branly. Minutes of proceedings, Volume 104 By Institution of Civil Engineers (Great Britain). 1891. Page 416 (Contained in, Comptes Rendus de l'Academie des Sciences, Paris, 1891, vol. exit., p. 90.)
- Experiments on the conductivity of insulating bodies, By M. Edouard Branly, M.D. Philosophical magazine. Taylor & Francis., 1892. Page 530 (Contained in, Comples Rendus de l' Academic des Sciences, 24 November 1890 and 12 January 1891, also, Bulletin de la Societi internationals d'electriciens, no. 78, May 1891)
- Increase of Resistance of Radio-conductors. E. Branly. (Comptes Rendus, 130. pp. 1068-1071, April 17, 1900.)
- "Wireless Telegraphy". Modern Engineering Practice VII. American School of Correspondence. 1903. p. 10.
- although Dr. Branly himself termed it a radio-conductor.
- Maver's wireless telegraphy: theory and practice By William Maver (jr.)
- United States Naval Institute (1902). Proceedings: Volume 28, Part 2. Page 443.
- Branly's filings used, were iron, aluminium, antimony, cadmium, bismuth, &c
- Minutes of proceedings, Volume 104 By Institution of Civil Engineers (Great Britain)
- Before closing the circuit a test is made to see that the current at make and break gives the same deviation on the galvanometer. The filings are then placed in the secondary circuit, and the primary opened and closed at regular intervals
- These deviations were obtained with an induction coil without core. The results obtained with a core were almost identical.
- A circuit was used consisting of a battery, the body to be tested, and a galvanometer; the electromotive force of the battery used was 1 volt at first, then 100 volts, and then again 1 volt.
- Text-book on wireless telegraphy, Volume 1 By Rupert Stanley. Pg 299.
- Collegio Pio-Latino-Americano Pontificio
- Dias, A., & Raposo, L. (1907). The Brazil of to-day: A book of commercial, political and geographical information on Brazil; impressions of voyage, descriptive and picturesque data about the principal cities, prominent men and leading events of our days, with illustrations and statistics. Nivelles: Lanneau & Despret, printers.
- Arthur Dias, in his book "The Brazil of To-day", refers to Landell de Moura, describing, among other things, the following:
[...] as soon as they arrived in São Paulo in 1893, began making preliminary experiments in order to achieve its purpose of conveying the voice of humans to a distance of 8, 10 or 12 miles, without wires.
- Prior to 1897 Tesla was transmitting signals to a distance of 30 miles from New York City to West Point. See the PBS website, "Marconi and Tesla: Who invented radio?" (ed. this is noted as having been accomplished in Leland Anderson's book Nikola Tesla's On His Work with Alternating Currents and Their Application to Wireless Telegraphy, Telephony and Transmission of Power)
- Leland I. Anderson, Priority in the Invention of Radio — Tesla vs. Marconi, Antique Wireless Association monograph, 1980, examining the 1943 decision by the US Supreme Court holding the key Marconi patent invalid (9 pages). (21st Century Books)
- Source: H. S. Norrie, "Induction coils: how to make, use, and repair them". Norman H. Schneider, 1907, 4th edition, New York.
- "Nikola Tesla". ieeeghn.org
- U.S. Patent 447,921, Tesla, Nikola, "Alternating Electric Current Generator".
- Alternators generating currents having a frequency up to 10,000 or 15,000 cycles per second were proposed several times for special purposes, such as high frequency experiments, etc. In 1902 Nikola Tesla proposed some forms of alternators having a large number of small poles, which would generate currents up to a frequency of 15,000 cycles per second. Later, the Westinghouse Company constructed an experimental machine of the inductor alternator type for generating currents having a frequency of 10,000 cycles per second. This machine was designed by Samms. It had 200 polar projections with a pole pitch of only 0.25-inch (6.4 mm), and a peripheral speed of 25,000 feet per minute. The armature core was built up of steel ribbon 2 inches (51 mm) wide and 3 mils thick. The armature had 400 slots with one wire per slot, and a bore of about 25 inches (640 mm). The air gap was only 0.03125-inch (0.794 mm). On constant excitation the voltage dropped from 150 volts at no load to 123 volts with an output of 8 amperes.
- The principles of electric wave telegraphy By Sir John Ambrose Fleming (1906). Page 12.
- Tesla: man out of time By Margaret Cheney. Page 357.
- At the time, electrostatic or magnetic conditions of the Earth were not know well.
- The principles of electric wave telegraphy By Sir John Ambrose Fleming (1906). pg 421.
- The principles of electric wave telegraphy By Sir John Ambrose Fleming (1906). pg 30.
- Journal of the Franklin Institute, Volume 136 By Persifor Frazer, Franklin Institute (Philadelphia, Pa.)
- "On Light and Other High Frequency Phenomena". Philadelphia/St. Louis; Franklin Institute in 1893.
- Electrical engineer, Volume 16. Pg. 208.
- The inventions, researches and writings of Nikola Tesla By Thomas Commerford Martin, Nikola Tesla. Page 486.
- Routledge, R., & Pepper, J. H. (1903). Discoveries and inventions of the nineteenth century. London: G. Routledge and sons. Page 545.
- Archie Frederick Collins, Wireless Telegraphy: Its History, Theory and Practice. McGraw publishing company, 1905. Page 131
- THE Electrical Engineer. Vol. XVII. January 10, 1894. No. 297. The Tesla Electrical Oscillators.
- Tesla would be awarded the American Institute of Electrical Engineers' Edison medal for this work.
- Electrical world, Volume 69, Part 2. Page 954
- "On Light and Other High Frequency Phenomena". Delivered before the Franklin Institute, Philadelphia, February 1893, and before the National Electric Light Association, St. Louis, March 1893.
- "Experiments with Alternating Currents of High Potential and High Frequency". Delivered before the Institution of Electrical Engineers, London, February 1892.
- The Electrical world, Volume 29
- Tesla explained his early methods of the transformation of electrical energy by oscillatory condenser discharges in his lecture "The stream of Lenard and Roentgen and novel apparatus for their production". (April 6, 1897).
- The same concepts were patented by Tesla in U.S. Patent 462,418.
- Fleming, J. A. (1919). The principles of electric wave telegraphy and telephony. London: Longmans, Green. Page 232.
- A. Oberbeck, "Ueber den Vcrlauf der Klcctrischen Schwingungen bei den Tesla'schen Versuchen," (tr., Over the course of the electric vibrations of Tesla's experiments) Wied. Ann. der Physii., 1895, vol. 55, p. B23.
- G. W. Pierce, "On Experiments on Resonance in Wireless Telegraph Circuits, Physical Review, vol. 24, February 1902, p. 152.
- Those two patents were issued in early 1900.
- These are known as electric circuit controllers.
- U.S. Patent 609,245, U.S. Patent 609,246, U.S. Patent 609,247, U.S. Patent 609,250, U.S. Patent 609,251, and U.S. Patent 611,719
- Corum, K. L., and J. F. Corum, "Tesla's Colorado Springs Receivers (A Short Introduction)".
- The Wireless age. (1914). N.Y. [New York] City: Macroni Pub. Corp'n (Wireless Press). "Wireless as a Commercial Fact, From the Inventor's Testimony in the United States Court in Brooklyn. G. Marconi, Part III". Page 75.(cf. "I read parts of a book by Martin, entitled "Inventions, Researches and Writings of Nikola Tesla," published in 1894".)
- Henry M. Bradford, "Marconi's Three; Transatlantic Radio Stations In Cape Breton". Read before the Royal Nova Scotia Historical Society, 31 January 1996. (ed. the site is reproduced with permission from the Royal Nova Scotia Historical Society Journal, Volume 1, 1998.)
- Marconi's Three; Transatlantic Radio Stations In Cape Breton.
- P.J.Papadopoulos, "Nikola Tesla; The Guglielmo Marconi Case, Who is the True Inventor of Radio?"
- The dispute over patent rights between the Marconi Company and Tesla began in August, 1914, when the Marconi Company sued Fritz Lowenstein, a German engineer, alleging that certain wireless apparatus sold by him to the United States Navy was made in violation of the Marconi U.S. Patent 763,772. It was announced then 'that Tesla would testify for Lowenstein, alleging that the Lowenstein devices were developed from Tesla patents U.S. Patent 645,576 and U.S. Patent 649,621, which were granted prior to the Marconi patent. In the present suit, Tesla bases his action on the allegation that his two patents were granted in 1900, and that the Marconi patent was not granted until 1904. (Wireless world, Volume 3 By Wireless Society of London. s.n., 1915)
- Tesla was the first, though, to expound the principles of the four-tuned system. The earlier two-tuned systems were not practical for commercial activity (as found in the United States court case). In addition, other prior work was conducted by others (such as by Hertz and Braun, but not excluding others) from which many of Marconi's devices and methods were derived. Marconi's U.S. Patent 676,332 Apparatus for wireless telegraphy , in which a more intricate system was disclosed than in his earlier patents, was filed after contributions made by other investigators.
- Date of Application 2 June 1896; Complete Specification Left, 2 March 1897; Accepted, 2 July 1897
- WH Preece, "Signalling through Space without Wires," Proc. Roy. Inst. Lond., 1897, vol. xv. p. 467.
- Report of the Board of Regents By Smithsonian Institution. Board of Regents, United States National Museum, Smithsonian Institution. 1899. Pg 249+
- The principles of electric wave telegraphy By Sir John Ambrose Fleming Pg. 429
- Wireless telegraphy and telephony without wires By Charles Robert Gibson. Pg 79
- Signals were also exchanged between Lavernock Point and the Flat Holm.
- Also known as a "Morse Inker".
- James Erskine-Murray (1907). A handbook of wireless telegraphy: its theory and practice, for the use of electrical engineers, students, and operators. Crosby Lockwood and Son. Page 39
- Marconi Receiver (Early Form), described from "Electrician" Primer No. 67, had an Aerial Wire, an Earth Wire, a Coherer, a Tapper, Choking Coils, a Dry Cell, a Relay, Battery, Shunts, and a Morse Inkwriter. The coherer consisted of silver electrodes contained in a vacuum tube (4 millimeters), the electrodes being separated by a thin layer composed of nickel and silver filings (nickel, 96 per cent.; silver, 4 per cent.).(The Electrical review, Volume 40. IPC Electrical-Electronic Press, 1897. Page 715.)
- Marconi's coherer consists of silver electrodes contained in a vacuum tube (4 millimeters), the electrodes being separated by a thin layer composed of nickel and silver filings (nickel, 96 per cent.; silver, 4 per cent.). The resistance of this is enormously reduced when electric waves imping upon the tube, and upon the resistance falling, a battery, in circuit with a Morse "inker," is able to work that instrument and record the signals sent out by the transmitter. In series with the Morse "inker" there is an electromagnetic "tapper" which restores the high resistance of the metallic mixture as soon as the signal has been received. Mr. Marconi's transmitter is of the Right pattern; that is to say, an induction coil causes sparks to pass between a succession of hollow metallic spheres, the middle ones of which arc partly immersed in vaseline oil. With a view, it would seem, of increasing the capacity (although the inventor says it is with a view of clearing intervening obstacles and thus obtain a free passage for his waves), he connects electrically to his transmitter either a metallic cone at the top of a pole, 100 feet high, or to a kite. (The Electrical world, Volume 29 Page 822.)
- Tesla, N., & Anderson, L. I. (1998). Nikola Tesla: guided weapons & computer technology. Tesla presents series, pt. 3. Breckenridge, Colo: Twenty First Century Books.
- Tesla, N., & Anderson, L. I. (2002). Nikola Tesla on his work with alternating currents and their application to wireless telegraphy, telephony, and transmission of power: an extended interview. Tesla presents series, pt. 1. Breckenridge, Colo: Twenty-First Century Books.
- The schematics are illustrated in U.S. Patent 613,809 and describes "rotating coherers".
- Santana High School (Brazil) today
- Journal of Commerce, a Brazilian economic newspaper (list of newspapers in Brazil)
- U.S. Patent 771,917 and U.S. Patent 775,337.
- U.S. Patent 775,846 claims a set of Hertz wave antennae, a source of cathodic waves, and a source of actinic waves, means whereby the changes of a pre-arranged code may be impressed upon one or more sets of the waves, and means to direct them toward a distant station.
- The distance being 7-5 miles.
- The distances were from 5 to 20 miles.
- Earlier, in 1885, a wired telephonic system was established here also. See, The Electrical review, Volume 17. Pg 81
- The shore mast was 105 feet high, and the wire on board the yacht 83 feet high.
- A summary of his work on wireless telegraphy up to the beginning of 1899 is given in a paper read by Marconi to the Institution of Electrical Engineers on March 2, 1899. See Journal of the li st. Elee. Eng., 1899, vol. 28, p. 273.
- Sandbanks, Poole
- The principles of electric wave telegraphy By Sir John Ambrose Fleming. Page 431-432.
- Journal of the Society of Arts, Volume 47 By Society of Arts (Great Britain). 1899. Page 519+
- "Milestones:First Operational Use Of Wireless Telegraphy, 1899-1902". IEEE Global History Network. IEEE. Retrieved 29 July 2011.
- Wireless telegraphy: its origins, development, inventions, and apparatus By Charles Henry Sewall, pg 144
- Henry M. Bradford, "Marconi in Newfoundland: The 1901 Transatlantic Radio Experiment"
- Henry M. Bradford, "Did Marconi Receive Transatlantic Radio Signals in 1901? - Part 1". Wolfville, N.S.
- Henry M. Bradford, "Did Marconi Receive Transatlantic Radio Signals in 1901? Part 2, Conclusion: The Trans-Atlantic Experiments". Wolfville, N.S.
- Heralded as a great scientific advance, there was—and continues to be—some skepticism about this claim, partly because the signals had been heard faintly and sporadically.
- In December, 1902, he established wireless telegraphic communication between Canada (Cape Breton) and England, the first message inaugurating the system being transmitted from the Governor General of Canada to King Edward VII, and a few weeks later a message inaugurating wireless connection between America (Cape Cod, Massachusetts) and Cornwall, England was transmitted from the President of the United States to the King of England. (Encyclopaedia of ships and shipping edited by Herbert B. Mason. The Shipping Encyclopaedia, 1908.)
- "Marconi at Mizen Head Visitor Centre Ireland Visitor Attractions". Mizenhead.net. Retrieved 2012-04-15.
- built in Wellfleet, Massachusetts in 1901
- Washburn, D. E. (1980). The peoples of Pennsylvania. Pittsburgh, Pa.: Univ. Center for International Studies. Page 193.
Listed by date [latest to earliest]
- Sarkar, T. K., & Baker, D. C. (2006). History of wireless. Hoboken, NJ: Wiley-Interscience.
- Hugh G. J. Aitken, Syntony and Spark: the Origins of Radio, ISBN 0-471-01816-3. 1976.
- Elliot N. Sivowitch, A Technological Survey of Broadcasting’s Pre-History, Journal of Broadcasting, 15:1-20 (Winter 1970-71).
- Colby, F. M., Williams, T., & Wade, H. T. (1930). "Wireless Telegraphy", The New international encyclopaedia. New York: Dodd, Mead and Co.
- "Wireless telegraphy", The Encyclopaedia Britannica. (1922). London: Encyclopædia Britannica.
- Stanley, R. (1919). Text-book on wireless telegraphy. London: Longmans, Green
- Miessner, B. F. (1916). Radiodynamics: The wireless control of torpedoes and other mechanisms. New York: D. Van Nostrand Co
- Thompson, S. P. (1915). Elementary lessons in electricity and magnetism. New York: Macmillan.
- Stanley, R. (1914). Text book on wireless telegraphy. London: Longmans, Green.
- Ashley, C. G., & Hayward, C. B. (1912). Wireless telegraphy and wireless telephony: an understandable presentation of the science of wireless transmission of intelligence. Chicago: American School of Correspondence.
- Massie, W. W., & Underhill, C. R. (1911). Wireless telegraphy and telephony popularly explained. New York: D. Van Nostrand.
- Captain S.S. Robison(1911). Developments in Wireless Telegraphy. International marine engineering, Volume 16. Simmons-Boardman Pub. Co.
- Bottone, S. R. (1910). Wireless telegraphy and Hertzian waves. London: Whittaker & Co.
- Erskine-Murray, J. (1909). A handbook of wireless telegraphy: its theory and practice, for the use of electrical engineers, students, and operators. New York: Van Nostrand.
- Twining, H. L. V., & Dubilier, W. (1909). Wireless telegraphy and high frequency electricity; a manual containing detailed information for the construction of transformers, wireless telegraph and high frequency apparatus, with chapters on their theory and operation. Los Angeles, Cal: The author.
- The New Physics and Its Evolution. Chapter VII: A Chapter in the History of Science: Wireless telegraphy by Lucien Poincaré, eBook #15207, released February 28, 2005. [originally, published: New York, D. Appleton and Company. 1909].
- Fleming, J. A. (1908). The principles of electric wave telegraphy. London: New York and Co.
- Simmons, H. H. (1908). "Wireless telegraphy", Outlines of electrical engineering. London: Cassell and Co.
- Murray, J. E. (1907). A handbook of wireless telegraphy. New York: D. Van Nostrand Co.; [etc.].
- Mazzotto, D., & Bottone, S. R. (1906). Wireless telegraphy and telephony. London: Whittaker & Co.
- Collins, A. F. (1905). Wireless telegraphy; its history, theory and practice. New York: McGraw Pub.
- Sewall, C. H. (1904). Wireless telegraphy: its origins, development, inventions, and apparatus. New York: D. Van Nostrand.
- Trevert, E. (1904). The A.B.C. of wireless telegraphy; a plain treatise on Hertzian wave signaling; embracing theory, methods of operation, and how to build various pieces of the apparatus employed. Lynn, Mass: Bubier Pub.
- Fahie, J. J. (1900). A history of wireless telegraphy, 1838-1899: including some bare-wire proposals for subaqueous telegraphs. Edinburgh: W. Blackwood and Sons.
- Telegraphing across space, Electric wave method. The Electrical engineer. (1884). London: Biggs & Co.
- American Institute of Electrical Engineers. (1884). Transactions of the American Institute of Electrical Engineers. New York: American Institute of Electrical Engineers. (ed., Contains Radio Telephony — By E. B. Craft and E. H. Colpitts (Illustrated). Page 305)
- John Joseph Fahie, A History of Wireless Telegraphy, 1838-1899: including some bare-wire proposals for subaqueous telegraphs, 1899 (first edition).
- John Joseph Fahie, A History of Wireless Telegraphy: including some bare-wire proposals for subaqueous telegraphs, 1901 (second edition).
- John Joseph Fahie, A History of Wireless Telegraphy: including some bare-wire proposals for subaqueous telegraphs, 1901 (second edition, in HTML format).
- Alfred Thomas Story, The Story of Wireless Telegraphy, 1904 
- James Bowman Lindsay A short biography on his efforts on electric lamps and telegraphy.
- Sparks Telegraph Key Review
- Principles of Radiotelegraphy (1919)