Telegraphic Communication Research Articles

Developments in the field of cable and radio telegraph communications (44–126)

Developments in the field of cable and radio telegraph communications (44–126)

Carrier telegraph systems

IN THE TIME of Samuel F. B. Morse, inventor of the telegraph, a single telegraph transmission of perhaps five words per minute represented the maximum use that could be made of a telegraph wire. Today over 97 per cent of all telegraph communication in the United States is carried on by automatic printers, which are known as teleprinters or teletypewriters. The word-per-minute speed of such machines is 60, and as many as 144 of these machines are now worked over a two-wire pair. The relative wire economies of the modern system and that in use even relatively recently, when the telegraph sounder still clicked away its 20 words per minute, are obvious.

Earthquake in Japan

ACCORDING to radio reports from Tokyo, a serious earthquake took place in southern Japan during the afternoon of September 10. The area most affected appears to have boon near Tottori, in which town half the buildings collapsed and more than 1,400 people may have been killed or injured. Tottori is some 100 miles north of Kobe where the earthquake was felt. The shock was also strong at Osaka. Around Tottori railway lines were blocked and telegraph communications were interrupted for a distance of 60 miles to the west. So far no news has been given concerning the area east of the town. Further news is awaited, though it is doubtful in the present state of conflict whether full details of damage done will be available.

Recent Earthquake

A SEVERE earthquake shook Quetta and the surrounding country in Baluchistan at 8.4 a.m. local time (2.34 a.m., G.M.T.) on September 29, 1941. The shock was also felt, though less distinctly, at Sibi, Mach, and Chaman, all in Baluchistan. The shock, which lasted according to human perception for thirty–five seconds at Quetta, was accompanied by heavy rumbling, and caused considerable apprehension. Although telephone and telegraph communications were temporarily dislocated, no serious damage or casualties are reported, and railways were unaffected. This lack of damage might easily be due to the thorough building of the new city after the calamitous earthquakes of May 31 and June 2, 1935. The re–planned city wasbuilt to earthquake–proof design according to the best building codes of California as worked out by seismologists and engineers. After–shocks tothe 1941 earthquake took place at 2.35 a.m., 2.54 a.m., 4.34 a.m., 5.4 a.m. and 8 p.m. (all G.M.T.) on the same day. It will be recalled that Quetta was levelled to the ground on May 31, 1,935, and that an area approximately a hundred miles in diameter was devastated. A severe aftershockoccurred on June 2, 1935, and altogether there were about 40,000 casualties (NATURE, June 15, 1935, p. 986 and several subsequent numbers). Severe shocks also occurred near Quetta in September and October 1937.

Discussion on “Empire telegraph communications” before the North Midland Centre, at Leeds, 28th February, 1939

Discussion on “Empire telegraph communications” before the North Midland Centre, at Leeds, 28th February, 1939

Empire telegraph communications

The paper deals with the engineering aspect of Empire telegraph communications. In order that the size and scope of these communications may be realized, the author begins by setting forth the components of the telegraph operating company, showing the systems contributed by each section.The engineering organization within the operating company is then dealt with, the training and necessary qualifications of telegraph engineers in the present service being outlined. Returning to the general aspect of Empire communications, the main traffic routes are discussed, with details of a number of main-line circuits. Some of the engineering requirements of the flow of traffic are touched on.Having dealt briefly with the system, the paper proceeds to enumerate the methods by which the collection and the delivery of messages are effected. The methods of signalling and the suitability of the different codes under varying circumstances are explained.The author then presents a short history of progress in cable telegraphy. Modern methods of signal shaping, balancing, and synchronous-regenerator working on cable circuits are reviewed. Where well-known methods are in use the descriptions are brief, full technical explanations being given only where information has not previously been published except in patent specifications. The items described in detail include the capacitance magnifier, the fork relay, the automatic bias corrector, and the automatic scrutinizer.There follow brief notes on recent progress and cable problems which are still being investigated.A brief outline of the methods of operating the wireless telegraph circuits is given, with details of the application of regenerator working to these circuits. A description of a method of double-frequency keying of wireless circuits follows. Finally, reference is made to the effects of varying cosmic conditions on wireless signals.

Discussion on “Empire telegraph communications” before the Institution, 15th December, 1938

Discussion on “Empire telegraph communications” before the Institution, 15th December, 1938

The author's reply to the discussions on “Empire telegraph communications”

The author's reply to the discussions on “Empire telegraph communications”

British Empire Telegraph Communications

DURING the last ten years very rapid progress has been made in both telegraph and radio communication throughout the British Empire. In a paper by K. L. Wood recently read to the Institution of Electrical Engineers, the engineering aspect of the whole of this world-wide communication is considered. A short history of progress in cable telegraphy is given,but full explanations are given of novel technical methods. Methods of operating radio are also described, and reference is made to the effects of varying cosmic conditions on radio signals.

An examination of the causes and nature of the interference to which the wireless communications of the mercantile marine are subjected

This paper sets on record the steps which have recently been taken to analyse the various types of interference to which the wireless communications of the mercantile marine are subjected.It deals with the interference caused by broadcasting and the interference caused by transmissions from other ships, both from the point of view of telegraphic communications and from that of direction-finding.

Radio Equipment for Cross Channel Air Services

IN March 1931 a demonstration was given by the International Telephone and Telegraph Laboratories of radio telegraphic communication across the English Channel on a wave-length of about 17 cm. (see NATURE of April 11, 1931, p. 564.) According to a note in the Electrician and the Electrical Review for November 18, a somewhat similar equipment to that used in the above demonstration has been ordered by the Air Ministry for use in connexion with cross-Channel flying services. This equipment will be manufactured by Messrs. Standard Telephones and Cables Ltd. in their Hendon factory, and it will operate on a wave-length in the neighbourhood of 15 am. The oscillations corresponding to this wave length will be generated by special valves and will be led to the transmitting aerial, which is less than one inch long, situated at the focus of a circular reflector about 10 ft. in diameter. This reflector will be focused on to a similar reflector at the receiving station. The equipment ordered by the Air Ministry will be located at the Lympne air-port, near Hythe, and will operate in conjunction with a similar equipment ordered by the French Air Ministry to be situated at St. Inglevert aerodrome, nearly seven miles south-west of Calais. It will be used for announcing the arrival and departure of aeroplanes that are not fitted with radio, and for routine service messages. An interesting feature of this new service will be the use of teleprinters for both receiving and transmitting messages. In this way typewritten messages will actually be sent across the Channel by radio, thus providing a permanent record at each end. It is expected that the station will be in opera tion early next spring and its use will relieve the volume of traffic at Croydon and Lympne radio stations very considerably.

Marconi Beam Stations for Shanghai

NEW Marconi transmitting and receiving stations are to be erected near Shanghai for the operation of the proposed short-wave beam services between China and Europe and the United States. A unique feature of the installation will be the inclusion of auxiliary Marconi apparatus enabling the transmitters to be utilised for broadcasting services when they are not in use for telegraphic communications. The auxiliary apparatus for this purpose consists of a modulating equipment which can be connected to either of the telegraph transmitters to provide telephone signals of broadcasting quality. A complete set of Marconi studio equipment is also to be supplied to enable the service to be conducted in accordance with the most modern practice. The aerial system of the transmitting station is of particular interest. For the commercial telegraph services to Europe, of which the principal is the service to Great Britain, two bays of beam aerials, accurately oriented to concentrate their signals on the receiving stations, are to be erected, one being tuned to the wave-length of 17 metres and the other to 26 metres, the wave-lengths allotted to these circuits. A third beam aerial array will be directed on San Francisco for the American service. In addition, there will be four omni-directional aerials, one of which will be used for broadcasting. The others are provided to afford the station the maximum flexibility in the range and extent of its telegraphic services. At the receiving station four high-speed commercial service receivers of the Marconi beam type are to be installed, with two beam aerial systems directed on Europe and two on San Francisco. Four omni-directional receiving aerials are also to be supplied for the reception of short-wave signals from other countries with which beam services are not required. On the completion of these stations near Shanghai a direct commercial wireless circuit will be provided for the first time between Great Britain and China.

Power supply for telesraph service

FASTER telegraphic communication is expected in this day of increasing speed of transportation; and speed must be accomplished with accuracy and the highest degree of service continuity. In order to meet these service demands electrically-operated devices in great variety, including belt-type message conveyer and pneumatic tubes in the larger offices, are finding their way into telegraphic service in ever-increasing quantities. Thus it is that the power plant is more than ever the heart of the system and every means must be provided to maintain an absolutely unfailing supply of electric energy.

Discussion on “Naval wireless telegraph communications” before the Wireless Section, 4th December, 1929

Discussion on “Naval wireless telegraph communications” before the Wireless Section, 4th December, 1929

Principal magnetic storms recorded at the Cheltenham Magnetic Observatory, April to December, 1927

The most severe magnetic storm of the year was recorded at the Cheltenham Magnetic Observatory on October 12, 1927. It began abruptly at 5h 26m Eastern (75th meridian) standard time, and continued until 19h 15m. The extreme values occurred at the following times: West declination, maximum at 6h 34m, minimum at 8h 06m, range 2° 17′; horizontal intensity, maximum at 13h 43m, minimum at 6h 31m, range 519γ; vertical intensity, maximum at 6h 38m, minimum at 14h 26m, range 344γ. The most active portion of the storm corresponded with the period during which there was reported to be interference with telegraphic communication.

Magnetic storm of April 13–14, 1927, as recorded at the U.S. Coast and Geodetic Survey Magnetic Observatory at Cheltenham, Maryland

The storm was of only moderate intensity but it is of especial interest because of the serious interference with telegraphic communication, especially in Canada, occurring at the same time, and the presence on the Sun of an unusual distribution of small sunspots. The storm began abruptly at 23h 48m, Greenwich mean time, on April 13th. After the characteristic features of a sudden commencement, conditions were fairly quiet from 1h to 5h 22m on April 14th, when the principal portion began, which lasted until about 17h.At the beginning there was a sudden increase in west declination of 3′.2 followed immediately by a decrease of 5′; a sudden decrease in horizontal intensity of 27γ followed by an increase of 36γ to the maximum value of 18860γ at 23h 49m; the beginning in vertical intensity was scarcely perceptible. The extreme values occurred as follows:

The Sun, the Earth's Atmosphere, and Radio Transmission

THE immense present-day importance of radio communication has directed the attention of a wider circle than ever before to the conditions prevailing at great heights in the atmosphere. Even to the professional meteorologist it seemed formerly that what happens above a height of 30 or 40 kilometres has no bearing on the practical affairs of humanity, however interesting the problems of these upper levels might be to the pure theorist. Almost the only influence of these levels upon the technical operations of mankind seemed to consist in the occasional interruption of telegraphic communication at times of great magnetic storms and auroral displays; the interference was pretty clearly due to currents induced in the earth and the cables by the rapidly varying magnetic field, but the direct association of the latter with the upper atmosphere was somewhat hypothetical, though the auror e were quite indubitably atmospheric phenomena.

Principal magnetic storms recorded at the Cheltenham Magnetic Observatory, April to June, 1926

(Lat. 38° 44′.0 N.; long., 76° 50′.5, or 5h 07.4mW. of Gr.)

Cipher printing telegraph systems: For secret wire and radio telegraphic communications

This paper describes a printing telegraph cipher system developed during the World War for the use of the Signal Corps, U. S. Army. This system is so designed that the messages are in secret form from the time they leave the sender until they are deciphered automatically at the office of the addressee. If copied while en route, the messages cannot be deciphered by an enemy, even though he has full knowledge of the methods and apparatus used. The operation of the equipment is described, as well as the method of using it for sending messages by wire, mail or radio. The paper also discusses the practical impossibility of preventing the copying of messages, as by wire tapping, and the relative advantages of various codes and ciphers as regards speed, accuracy and the secrecy of their messages.

Cipher Printing Telegraph Systems For Secret Wire and Radio Telegraphic Communications

This paper describes a printing telegraph cipher system devetoped during the World War for the use of the Signal Corps, U. S. Army. This system is so designed that the messages are in secret form from the time they leave the sender until they are deciphered automatically at the office of the addressee. If copied while en route, the messages cannot be deciphered by an enemy, even though he has full knowledge of the methods and apparatus used. The operation of the equipment is described, as well as the method of using it for sending messages by wire, mail or radio. The paper also discusses the practical impossibility of preventing the copying of messages, as by wire tapping, and thte relative advantages of various codes and ciphers as regards speed, accutracy and the secrecy of their messages.