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BEAM WIRELESS, Evening Post, Volume CXIII, Issue 3, 5 January 1927
HISTORY OF THE ENTERPRISE
!- EXTRAORDINARY ACHIEVEMENT.
The wireless stations constructed at Bodmin and Bridgwater for communication with Canada on the Marconi short wave beam principle having passed their official Seven days' test in the General Post Office announced that a high-speed wireloss telegraph service between Groat Britain and Canada through theso stations would bo openod on 25th October. With tho first Dominion, beam service thus established, Great Britain's -world leadership in wireless communication is maintained. As the homo, of Sonatore Marconi's
first long-distance wireless experiments
Great Britain was tho pioneer country in commercial wireless telegraphy. And
now, with the modern high-power valve | transmitting station at Rugby for allround communication, and the Marconi beam stations for direct communication between the Mother Country and each .of the Dominions, it possesses tho most complete, up-to-date, and efficient wireloss service of any country in tho world. A TAR-REACHIHa REVERSAL or policy. It was in 1923,-after several years of distussion, that tho Government definitely decided to proceed with the erection of wireless stations to communicate with each of tlie Dominions. - The Dominions had boon pressing for such a service for some years, and when the British Government's decision was taken they immediately put arrangements in hand for the erection of corresponding stations to form a complete ■ Empire wiroless service. Whilo negotiations wore proceeding with tho Marooni company for tho erection of high- ' power long-wave valve transmitting stu- ' tions to carry out thoso services, Sena- , tore Marconi became convinced, as the ' result of his experiments, that a new I system of wireless telegraphy could be .developed that would enable these Imperial services to bo carried out much more efficiently and at much lower cost than was contemplated by the high- . power long-wavo wireless stations. His plan was to. use short wireless waves— of 100' metres or loss—which, contrary to the generally accepted theory at that time, he had proved'to be quite.reliable for communicating over groat distances; 'and to increase tho strength of signals and tho speed and efficiency of working by employing reflectors to concentrate into a narrow beam the wireless onergy at'the transmitting station and to reflect a greater amount of energy on to the receiving aerial at. the receiving Station. As Senatore Marconi has said, a considerable amount of courage was necessary to propose such a revolutionary- change. He had no uncertainty, however, neither had the company,of which he is the 'chair-' man;' and the proposal was put beforo ,tho Government. So convincing were the arguments in favour of the new system that tho whole technical policy 01' Imperial*wireless communication was, revised • and the Government entered into a contract with Marconi's Wireless Telegraph - Company, Ltd., to build short wave beam wireless stations in Kngland, to-communicate witli Canada, South Africa, Australia, and India.' 't ■ Tho];-Governments and wiroless. companies in each of these Dominions wore equally impressed with -the value o£ 1 the beam system and contracted with tho Marconi Company to build corresponding stations to communicate with those being erected in England. Tho building of tho stations was started in April, 1925. They have been longer under construction than was at' Jirst anticipated, but this has been duo to tho fact that research work has been carried on simultaneously with constructional work, and many. valuable improvements on tho original designs have been mado as tho work progressed. Power valves have had" to be specially designed to deal with the extra high frequencies of short wave working, and the Marconi oil-cooled valves at the transmitting station are the most efficient of their kind in tho world. HIGH SIGNALLING SPEED.
The official Post Office tests laid down that the stations for tho Canadian service should bo capable of communication at a speed of 500 letters per minute each way (exclusive of any repetitions necessary to ensure accuracy) during a daily average of 18 hours, and that a demonstration fulfilling this condition ■ should be given by actual working for seven consecutive days. This test took place - between 7th October and 14th October, and the 'guarantees—which wore regarded by everyone as being extremely stringent—havo been fulfilled > During these and tho preliminary tests carried out 'by the Marconi Company speeds of 1250 letters'per minute in each direction, equal to 2500 letters per minute over the complete j circuit, havo beenworked for many hours on end. • Counting every hour of the seven days test tho averago speed of signalling haa been about 600 letters per minute in each direction, or 1200 letters per minute for the complete circuit. This result abundantly justifies the claims made for tho beam system, and indicates that the stations will bo capable of handling.all tho traffic that is likely to be available between England and Canada' for some years to come. Wireless telegraph engineers arc used to high signalling speeds, but the extraordinary achievements of tho beam system havo been the cause of several surprising and amusing incidents, duo to 1 the speed, of working during tho recent tests. On more than ouo occasion the engineer has put v message on the Canadian circuit, and before he could reach tho recording room in tho same building he was handed the roplv from Canada.
ADVANTAGES TO COMMERCE. The institution of direct Marconi wireless telegraph services .between London and Paris and other Continental centi-03 has shown that new telegraph traffic is created by the 'provision of new and rapid means of communication? It can therefore bo confidently anticipated that the establishment of tho beam services, which can be worked at a speed which will enable largo volumes of traffic to be rioalt with in the shortest possible time, will creato . new business that has not previously been possible, and so bestow a great benefit on the commerce of Great Britain and Canada. in this connection it is interesting to note that Canada has shared with Great Britain tho pioneer position in commercial wirolcss communication since Scnatoro Marconi's earliest long-dis-tance experiments in December, 1901— .of which tho 25th anniversary will bo celebrated this year; and tho establish- • inent of the first trans-Atlantic commercial wireless service between Clifden, Ireland, and Glace Bay, Canada, in 1907. By being tho first Dominion to open a beam service it continues to take s, lead in the development of this means of communication. Tho beam transmitting station in Canada is situated at Druminondville, 30 miles cast of Montreal, and tho re- , ceiving station at Tamauhichc, 25 miles north of Drummondvillo. Theso stations aro linked up by land lino to tho contral office of the Canadian. Marconi Company in Montreal in the same way■that the English stations ate linked
to the General Post Office. ' Beam stations are also being erocted in Canada for direct communication with Australia, and corresponding beam stations arc being built at Melbourne.
COMPLETING THE EMPIRE SCHEME.
_ The sites occupied by the beam stations at Bodmin and' Bridgwater for communication with Canada are also utilised for the stations to be used for communication with South Africa. These South African'stations are practically comploie. Similar stations arc being built at Totney, near Grimsby, and at "Winthorpe, near Skegness, for communication with Australia and'lndia—the Grimsby stations being transmitting stations and tho Skegnoss stations receiving stations. Corresponding stations aro being built in tho Dominions near Capetown, Mslbourno, and Bombay. All thoae stations aro in an advanced state of construction, and are expected to bo opened within the licxt few months. This will complete the present Imperial schemo; but outsido this schemo the Marconi Company is already engaged on a considerable development of commercial telegraph services on tho beam principle. Tho company holds a license from tho Post Office to conduct wireless telegraph services with certain Continental countries and with all other foreign countries outside Europe. In addition to the wireless Stations it has been operating on these services for some years, it has a beam-station nearly completed at Dorchester for'communication. .'With North and South America. A corresponding station is also in. process of erection at Rio do Janeiro.
Another important development in Which beam stations are included, and are already under construction, is the Portuguese scheme for linking up Portugal and its colonies. Some timo ago tho Marconi Company obtained a concession from the Portuguese Government for the establishment of wireless telegraph stations in Portugal and its colonies for tho purpose of linking them together and establishing wireless "communication with other parts of the:wOrld. These stations are how boing built at Lisbon, in the Capo Verde Islands, tho Azores, and in East and West Africa. When they aro completed, I wiroless sorvices will bo established with England and the principal Continental countries s and with South America. The Marconi short-wave beam stations'in this scheme arc being erected at Lisbon, Loanda, and Mozambique! . ' ADVANTAGES OP THE BEAM SYSTEM. It is claimed that a beam wireless station has tho following distinct advantages Over any other form of telegraph communications for point to point communication over'similar distances: Tho capital expenditure involved is considerably loss; it is more economical to run and maintain; and it is by far the most speedy method of, communication yot devised. The speed of working of tho beam system is at present ■limited only by the mechanical limitations of the transmitting and recording instruments, and when suitable moans of recording over land lines at higher spoeds than at present obtainI able have'been developed it will be possible to increase correspondingly tho over-all speed of signalling. Tho results of tests between -England and Canada have shown that tho use of beam aerials at both transmitting and receiving stations lias resulted in' a strength of,signal some 100 times that obtainable with non-directional transmitting and receiving aerials at each end, and utilising the same power; and it has enabled the servieo to bo carried on under 'conditions when signals obtained by utilising non-diroctional aerials were " hardly appreciable. At | the same time the uso of beam aerials has "resulted in>avery large degree of freedom' from atmospheric disturbance. DESCRIPTION Or THE STATIONS.
■.;Tho;:B6dinin'.station,; which: is :builti upon .a ■ stiip'.y.of,.'la,ud'. bordering ./the •main Bodmin-Truro '.road,,;, 4A , - mile 3 ;sputh-wcst ; of the/Cornish country to wny comprises., two transmitting .; . sys- ■ terns, onc/.i'or, communication; with Can-! Ada and'the; other for. communication' with Squih. Africa.'.'' The receiving sta- . tions,'arc situated near North' Pothe- 1' ton, ',-2j- miles' south: of Bridgwater,? off . the main ' Bridgwater-Tauntou road. ' ■■:
The masts and aerial system—the de.sign of'which is peculiar to tho • shortwave beam system and is entirely different from the design previously used in commercial wireless stations—aro similar at both stations. There arc five lattico steel masts for each service erected in a straight line and aligned so that tho great circle 'bearing on the distant station is at light angles to tho line of masts. Tho beam is therefore projected, accurately in the direction of the . stations with which communication is being maintained. Tho masts are 277 feet high,- with cross-arms at the top, measuring 90 feet from end to end, and giving an additional 10 feet to Iho height of the mast. The aerial and reflector.'systems consist of a number of vertical wires, forming as it were a wire curtain, suspended from steel- cables attached to the cross-arms and running along each side of the row of masts. Tho aerial system is on one side of the masts, facing the. distant station, and tho reflector system is on the opposite side.
The transmitter—which, is, rated at only 20 kilowatts —is of an entirely new design throughout, and is extremely compact^ Stability of wave length, which is of the greatest importance in short wavo work, is obtained by exceptional caro in the design of the set.
Tho transmitter is operated direct frojii the Central Radio' Office at the General Post Office in. London. The land line is led in to a relay attached to the first panel of the set. By this means. tho operator in London is in full control of the transmitter, and at the moment he presses his key or foods his signalling tape into a high-speed telegraph instrument, the signals he is sending are being recorded in the telegraph offico in Montreal, which is connected in a similar manner to the Canadian wireless receiving station.
In tho same way tho messages put on to tho -transmitter in tho telegraph office in Montreal are instantly recorded at the General Post Office in London, after having travorsod the Atlantic and passed through tho beam receiving station at Bridgwater.
-.Now: that the Canadian station has been completed satisfactorily, tho preliminary tests will at once be proceeded ■with in the case of communication between England and-South Africa.. On. the completion of theso tests, those with Australia and India will.follow, the 'construction of beam stations for 'all theso services being nearly completed.
BEAM WIRELESS, Evening Post, Volume CXIII, Issue 3, 5 January 1927
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