MARCONI relates HOW WIRELESS BEGAN

Radio Record, Volume V, Issue 25, 31 December 1931, Page 3

MARCONI relates HOW WIRELESS BEGAN

Senatore Marchese Marconi, probably the best known figure in radio history recently told in his own words from the B.B.C. the thrilling story of how radio began. Through the courtesy of "The Listener" we are able to reproduce in full that remarkable talk. HE seed from which it can be truly said that wireless has sprung was the discovery made by Michael Faraday, one hundred years ago, that it was not necessary for two electrical circuits to be in actual physical contact in order that electric energy might pass across a small space between them. This great discovery was followed by the masterly Electro-magnetic Theory of Clerk Maxwell, published in 1865, in which he clearly visualised the existence of electric waves in space, of which experimental proof was given by Heinrich Hertz in 1888. In 1895, I began my own researches with the express intention of utilising electric waves for telegraphing across considerable distances, and succeeded at that early date in transmitting and receiving intelligible

telegraphic signals across space ovet distances of about one and _ threequarter miles. These first tests were soon followed by important improvements which made possible tuning and selectivity and by new discoveries, such as that of the enormous distance over which these waves can travel and be detected notwithstanding the interyening curvature of the earth, which discovery enabled scientific investigators subsequently to learn something new in regard to the constitution and condition of our atmosphere at great heights, thus opening up vast and ertile fields of useful research which have lately allowed us to scrutinise still more effectively some of the mysteries wrapt up in the space which surrounds our earth. The beginnings of telephony as we now know it, whether operated by line or radio waves, naturally date from the invention of the electromagnetic telephone receiver .and the carbon microphone. This takes us back to the days before Hertz, actually to the time of Maxwell, for it was in 1861 that Philip Reis, of Friederichs-

dorf, using a primitive form of electro-magnet and an imperfect eleag trical contact, obtained by means of instruments connected together wires the first experimental results that deserve recording. Antonio Meucci in 1871, and Elisha Gray in 1874, among others took out patents for apparatus which was certainly able to trans speech, though not very perfectly; but it was reserved for Dr. Grah Bell in 1876, to evolve the first practical form of telephone. This was later modified for commercial use employing a bar magnet, a speect coil at one end and an iron diaphragm, and was given the well-knowsi hell shape associated with his name. Many of the present desk telephone receivers retain this shape, but a horse-shoe magnet is used instead o a bar magnet. For the carbon microphone, which was invented two years latet, we are indebted to Professor Hughes, Thomas A. Edison and the Reva Hunnings, as their discoveries in this field were all made public in the same year, 1878. From that time the telephone began its conquest of land communications, and later speech was transmitted by submarine cable across narrow sea channels. But there for the time being development stopped. . Te was the position in 1900, when Professor R. A. Fessenden made the first attempt to transmit speech through space by electric waves, and was able to effect some sort of communication over a distance of one mile. As is well known, the speech currents are superposed on some other form of current or high frequency wave which must be unbroken, not intermittent, and the spark transmission by inductio# coil and interrupter of that day, although quite satisfactory for telegraph working-I was then effecting radio communication over _ thirty-six tmiles-because of the dead intervals between the sparks, was quite unsuitable for telephony. To approach the required condition of carrier current. Fessenden endeavoured to make the wave trains of the sparks overlap by increasing the number to 10,000 per second and he obtained some small measure of success. (Continued on page 19.4

How Wireless Began. (Continued from page 2.)

In 1902 a distance of twenty miles was covered by E. Ruhmer; and then, in 1906,- a real advance Was achieved by TFessenden by ¢émploying for the first time a high Zrequency alternator which gave him. a useful carrier wave of 20,¢ 000 cycles per second. ‘This enabled him in the following year to transmit speech from Rrant Rock to Jamaica, Long Island, a distance of about 200 It is interesting to note here the development in wireless telegraphy during this period. In December, 1901, by means of stations specially constructed for that purpose, I was able for the first time to transmit and receive telegraphic signals right across the Atlantie Ocean, from Poldhu in Cornwall to St. John’s, Newfoundland, x distance of 1800 miles, thus discovering that really big distances were possible because the electrical waves would follow the earth’s curva-. ture round the globe. Early in 1902, during a voyage on the American liner Philadelphia to New York, I was able to receive signals from Poldhu for the whole distance at night time, although Curing the day the transmission range fell to 700 miles, thus discovering the now well-known fact that wireless signals transmitted by wavelengths of *:} few hundred metres can be received cyer much greater distance by night than during the hours of daylight. My voyage to the United States on s.s. Lucania in the following year, during which news messages were received by wireless from Poldhu daily, is deserving of note because the results were so successful that a number of other ships were fitted with long-distance receiving apparatus, and: a Wireless Broadcast . News Message Service te liners was officially opened in 1904. This telegraphie news. service has continued withcut a break up to the present time. The broadcasts from Poldhu during the War were, of course, of an official nature only, but the usual commercial service was resumed immeiliately after the War, Poldhu continned fo send out the news until May, 1922, (Concluded on page 30.)

How Wireless. -Began (Continued from page.19.) |

and-the telegraphic broadcast was then {aken .over first by Clifden, then Carnaryon, then Leafield, and is now sent out.from Rugby. It: was about 1906 that my company put up a proposal to the British Post Office that they should be allowed to broadcast news to all the newspapers in-the country. However, this was not agreed to. Returning now to a consideration of the general progress in wireless telephony, at the time of Fessenden’s 1906 tests, ‘while I was personally very much oceupied in improving my transatlantic stations at Clifden and Glace Bay, Nova Scotia, Captain H. J. Round, one of my assistants, had a small are transmitter working near the battery in New York, from which speech and phonograph records were transmitted to yarious places in New York, including the "Times" building and _ ships lying in the docks. There were, of course, no valve amplifiers in existence at that date,- and for best results the microphone was connected in the aerial circuit. In order to use power in the serial heavy current microphones were required. The best of these were the liquid microphones of Q. Majorana and G. Vanui. Employing are transmitters Majorana was able to transmit in 1908 from Rome to Sicily, a distance of 300 miles, and Vanni, in 1912, communieated from Rome to Tripoli, a distance of GOO miles. The invention of the Fleming valve in 1904 and the threcelectrode valve of Lee de Forest in 1907 enabled the disebility which had delayed the commercial development of wireless tele--phony to be removed, and the present state of the art to be realised. AS was to be expected,’ with the new system early results were obtained working over short distances. It was in June, 1913, that Dr. Meissner employed the oscillating valve for the first time as carrier wave generator for transmitting speech between Berlin and Nauen, a distance of 23 miles. My first tests with a valve generator were made in the following year. In March, 1914, I had the apparatus installed on an Italian warship ‘at Augusta in Sicily, and speech was received on a second vessel. The two ships steamed out on to the high seas for further tests off the Sicilian coast, and consistently perfect reception was registered over a distance of 35 kilometres, a distance subsequently increased to 70 kilometres, with very limited power. Communication was coustantly maintained throughout a period of 12 hours, the experiments including periods when -signals were transmitted entirely over sea and also when land intervened. One complete wireless installation was also sent to New York and communication was established be--tween New York and Philadelphia by telephone working both ways. On the outbreak of war, experiments in wireless telephony were discontinued commercially and were carried out only in connection with the military ser-

vices, as far as this country was concerned; but in America commercial research continued, and at the end of 1915 the American Telephone and Telegraph Co., working in conjunction with the Western Electric Co., succeeded, when conditions were favourable, in transmitting speech from the U.S. 1:a¥al station at Arlington to the Biffel Tower Station, Paris, a distance of 8800 miles. Over 300 valves were used in the oscillator and: modulator circuits, On the conclusion of the War it became possible for European countries. to resume their tests; and in March, 1919, with the object of demonstrating that trans-Atlantic telephony could be achieved using comparatively small power, one-way communication was established and _ satisfactorily maintained for ten days with Louisburg, Canada, by transmission from my station at Ballybunion, Ireland, using a valve transmitter with only 2.5 kw. output from the generator, a& Wavelength of 3800 metres and an aerial 500 feet in height. In the same year my assistant, Mr. Cc. S. Franklin, carried out a shortWare telephony Beam test on 15 m across the Irish sea, a distance of 80 miles, and work on this wavelength was continued in 1921, when two-way telephone communication was established between Hendon and Birmingham, a distance of 97 miles, using reflectors. Then, in 1920-21, following a successful test of duplex telephony on 100 m. between Chelmsford and Southend, experimental stations were erected by my engineers at Southwold and Zandfuort, Holland, which worked duplex across the North Sea with 1 kw. to the eerial on 100 m. At Christiansund, Norway, good quality telephony was receiyed from these stations both at night and during the day time; while at Oslo, a distance of 700 miles, yery loud and constant signals were received during the night, but the day reception was reported variable. The year 1920 is memorable for 2 number of important wireless telephone transmissions which had both news and entertainment value. and thus had the same character that broadcasting has to-day. To encourage public interest, demonstrations were given to show that no special skill was required to talk into the telephone aud that musical items could be transmitted and satisfactorily received. In February, 1920, a programme of vocal and in‘strumental music for two half-hourly periods each day for a fortnight was broadcast from my Chelmsford station using about 5 kw. in the aerial, and the same wavelength of 2800 m. which

was being. employed by, Poldhu for the news broadcast.to ships. This was in order to test the range of the transmitter. Amateurs and the . shipping companiés were advised’ and asked to send in reports, Dame Nellie Melba gave her first. broadcast in. June, 1920, from this station, and. Lauritz. Melchior in July. World-wide interest was aroused by these broadcast eoncerts and good reception was reported from distances as far away as Persia and Canada. In November, 1920, the Westinghouse Wlectric and Manufacturing CGompany,. having given due notice ‘beforehand, broadeast the re-

turns of President Harding’s election from their Pittsburg station as they came to hand. Many thousands of people were ready with receivers, and When the results came through they were thus able to anticipate the newspapers. ; This caused a great sensation. During the year 1921, amateurs and the commercial interests in the United States erected broadcast stations in considerable numbers, and the public demand for receivers grew at an extremely rapid rate, resulting later in an enormous development of broadcasting in the United States. I cannot detail here all the steps which put British broadcasting finally on a permanent basis; it is sufficient to say that in order to satisfy the experimental needs of the British amateur the Postmaster-General finally agreed, in 1922, to a limited service of vocal and gramophone selections and calibration signals being sent out from my company’s station at Writtle. The moyement begun on this basis rapidly became a popular one in which the non-technical listener who required to be interested or amused by news or music predominated, aud his needs are certainly well catered for to-day. Commercial telephony is satisfied with intelligibility and a hand or wall microphone; but for the transmission of music and broadcasts from groups of artists nothing less than true reproduction and a microphone that can pick up the variations of sound at a distance and yet reject mechanical vibrations is demanded. This has led to inten-

sive development in studio design and equipment, the first efforts in this direction being ‘applied at the original 210 station at Marconi House, opened in November, 1922, and-later, with great thoroughness, at the new sttidios, when 2LO was removed ‘to the headquarters of the British Broadcasting -Corporation at Savoy Hill. I understand that the elaborate and comprehensive equipment of the future home of British broadcasting at Langham Place, London, leaves nothing to be desired, and I am convinced that, under the able direction of Sir John Reith the British Broadcasting Corporation will worthily maintain its recognised position as the leading broadcasting organisation. At one time it was a stock argument against the use of wireless that messages sent by this means could be picked upin all directions, This chart acteristic. however,"has made it’ San idedl method for communicating with moving objects such as ships at sea or aeroplanes in flight, and with the advent of broadcasting this widespread radiation has became a most valuable feature. There are, however, many services for which a more confined channel has distinct advantages, and this requirement, T am glad to say, is effectively wet. by my Beam system, by means of which signals can be concentrated and directed in any desired direction and the power necessary is reduced. to a minimum. Directional or Beam wireless transmission has made worldwide telephony possible, and to-day we can speak to our friends at the ends of the earth or on ships at sea whereve they may be, and recognise with the pleasure of personal contact the familiar intonations of their voices. On May 30, 1924, I was able to speak from Poldhu to Sydney, thus conveying intelligible speech from England to Australia for the first time, and last year, when on board my yacht Pletira in the Mediterranean, utilising one of cur small sbip wireless telephone installations, I again spoke whenever I wished to do so to friends in Australia over a distance of 9000 miles. I also Spoke to others in London, Buenos Aires, Rio de Janeiro, New York. Montreal and Capetown, a range covering practically the whole world. The great need of the present day is for a better understanding between men and nations, and this understanding can be fostered and helped by improvements in our communications. The most direct end satisfying means of communicagon between men is | the spoken werd. In this respect, broadcast tetephony occupies a unique position as being the most potent means for the instantaneous and universal dissemination of information, instruction aud entertainment that the world has ever known. . I am happy if by any efforts of mine I have been able to make some contribution towards international sympathy and understanding.