2868 Emergency Installa- tions. INTERNATIONAL RADIO CONVENTION. NOVEMBER 25,1927. (2) Stations carrying on a service of radiotelegraph correspond- ence, press news, etc., with ships at sea must observe silence during the intervals indicated above. Only the transmissions provided for in Article 19, sections·25 to 27, may be made during these intervals. (3) As an exception, however, land and ship stations equipped to correspond by means of continuous waves may continue to work during these periods; if they are in a position to maintain at the same time a satisfactory watch on the distress wave as provided for in paragraph (1) of the present section. §3. The following rules must be observed in the operation of stations in the mobile service using Type Al waves of the band 100 to 160 kc/s (3000-1875 m.) which is assi~ned to the mobile service. a) Every coast statiori carrymg on communications on a long continuous wave must listen on the wave of 143 kc/s (2100 m.) unless it is otherwise indicated in the nomenclature. The coast stations shall transmit all its traffic on the wave or waves especially assigned to it. b) When a mobile station deAires to establish communication on a l!'ng continuous wave with another station of the mobile servictl, it must employ the wave of 143 kc/s (2100 m.) unless it is otherwise indicated in the nomenclature. This wave, designated as the gen- eral communication wave, must be employed: (1) For calls and answers thereto. (2) For sending signals preliminary to the transmission of traffic. c) A mobile station after havin~ established communication on the ~eneral communication wave, With another station in the mobile serVICe, may transmit its traffic on any wave in the authorized band on condition that it does not disturb the work of a coast station or work in progress on the calling wave. d) As a general rule, every mobile station, equipped for service on long continuouA waves and not engaged in communication on another wave, must, in order to permit the exchange oi traffic with other stations of the mobile service, return to the wave of 143 kc/s (2100 m.) for 10 minutes from the beginning of the 35th minute to the beginning of the 45th minute of each hour, Greenwich Mean Time, during the specified hours, according to the class to which the station in question belongs. e) (1) Coast stations shall transmit their traffic lists at specified times, published in the nomenclature, on the wave or waves which are assigned to them. (2) Besides the times thus fixed for this tranrnission of their traffic lists, coast stations mey call mobile stations individually, at any other time, according to circumstances or according to work which they have to carry on. These individual calls may be made on the wave of 143 kc/s (2100 m.) in regions where there is no congestion of traffic. j) The special provisions concerning the service carried on by land stations using long continuous waves shall be shown in detail in 8 special reference in the nomenclature. ARTICLE 18 Emergency installations §1. The Convention for the Safety of Life at Sea determines which ships must be provided w.i .th emergency installations and defines the conditions to be fulfilled by installations of this class. §2. In the use of emergency installations, all the provisions of the present Regulations must be observed.
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