Communication E V a

International Regulations.

Since the emission of waves from a wireless station affects receiving apparatus over a wide area if the apparatus is attuned to the waves, it follows that every wireless station on the globe monopolizes a certain wave-length or frequency inside a certain area. Indeed, as it is impossible to tune transmitting or receiving apparatus with absolute accu racy, each station may be said to monopolize a band of fre quencies. Therefore, to make telegraphic services useful, an allocation of a particular wave-length or frequency must be made to each station, due regard being taken of the area served by such station and of the proximity and needs of neighbouring sta tions. From this arose the necessity for international agreement and legislation, and a conference was called at Berlin in 1903, which prepared schemes for discussion at a second international conference meeting at Berlin in 1906. This conference discussed many details that had become of importance to the usefulness of wireless, including rules for handling and charging for telegrams, especially by ship's operators, and regulations for the prevention of interference and for the enforcement cf penalties. At the suc ceeding conference in London in 1912 a radiotelegraphic con vention was drawn up and was signed by nearly all the principal countries. This provided for the establishment of a central office for collecting and distributing information about the wireless serv ices of the world, and arranged for it to take its place as a branch of the Bureau of the International Telegraph Union at Berne. This radiotelegraph office had about one thousand wireless stations on its list in 1912 and nearly twenty thousand in 1926. The growth in number is due chiefly to the increased use of wireless at sea, which was greatly stimulated by the signing in 1914 of the International Convention for the Safety of Life at Sea. This convention, which was arranged in London in 1913, specifies the minimum of equipment and staff to be carried by ships of the various grades and for the hours of service.

A most important international radio conference took place at Washington in the autumn of 1927. The revised arrangements have not yet been ratified by all the Powers concerned, but the allocations of wave-length to different services provisionally adopted will probably be universally accepted. They are as follows:— Long Waves Approximate Service Frequency kilocycles wave-length ilocycles metres Point-to-point . . . . . . Below ioo Above 3,000 Mcbile and point-to-point . . . Ion-hio 2,725-3,0oo Mobile, including naval vessels . . iio-125 2,400-2,725 Mobile, merchant vessels. . . . '25-150 Mobile, calling wave. . . . . 143 2,100 Mobile. . . ..... 150-16o 1,875-2,00o Broadcasting or mobile and point-to point (as determined by regional agree ment) . . . . . . . 160-194 Broadcasting, mobile and point-to-point services for aircraft (subject to certain.

limitations) . . . . . . 194-285 1,050-1,550 Radio beacons . . . . . . 285-315 950-1,050 Aviation . . . . . . . 315-350 850-950

Mobile and radio compass . . . 350-550 . . . . . . 550-1,500 200-545 I Small vessel; . . . . . . 1,365 220It is proposed to allow mobile stations and point-to-point sta tions to share short wave bands as shown in the following table. Certain parts of the bands shown here as "point-to-point" are available for amateur stations or for short-wave broadcasting stations or are shared with mobile services. Certain parts of the bands shown here as "mobile" are similarly shared with point-to point services.

Short Waves Point-to-point service (including Mobile service amateurs and short-wave broadcasting) Approximate Approximate Frequency Frequency wave-length wave-length kilocycles kilocycles metres metres 1,500-2,750 109-200 1,715-2,250 133-175 52.7-105 33.7-36.6 6,675-8,200 36.6-45 I I ,000-I 1,400 26.3-27.3 8,550-11,0oo 27.3-35-I I 16.9-18.3 I 2,825-16,40.0 21,550-23,000 13.1-13.9 17,10o-21,550 13.9-17.5 13'1-13'45 Variations from this table will probably be allowed to existing important stations; all waves below 13.1 metres (above 23,000 kilocycles) remain free for allocation nationally.

The conference, among other recommendations, laid stress upon one which forbids the installation of spark sets above 30o watts input power on new ships after 1929, and the abolition of all such sets now existing on old ships on December 31, 1939. As for spark stations on land, they are to be abolished as rapidly as is possible. Moreover, all except small ships are recommended to be fitted as early as possible to receive continuous waves from 500 to 3,00o metres.

In accord with the International Convention, every important country has enacted domestic legislation to enable the interna tional provisions to be enforced. In Great Britain and Northern Ireland the control of wireless communications is in the hands of the Postmaster General, in virtue of the Wireless Telegraphy Act of 1904, which is renewed annually. The Act provides that no one shall install or work a wireless equipment, either for send ing or receiving messages, without a licence; and that when an applicant for a licence proves that his object is for experimental purposes solely, a licence shall be granted without rent or royalty. The application of the Act to shipping is regulated under the Merchant Shipping (Wireless Telegraphy) Act, 1919, and the Rules made by the Board of Trade under this Act. (W. E.) In the United States of America commercial wireless communi cation services are operated by private enterprise. Under the Act of 1927 the Federal Government has certain regulating powers to grant licences for radio stations, to license operators, to apportion wave-length assignments and other similar powers necessary to preserve the "public interest, convenience and necessity." This law is administered by an appointive group of five men known as the Federal Radio Commission. The United States was signatory to and has ratified the International Radio Convention of 1927.