2850 INTERNA.TIONA.L RADIO CONVENTION. NOVEMBER 25,1927. Tyrpe .AS: Continuous waves modulated at audible frequencv. Continuous waves, the amplitude or frequency of which is varied in a periodic manner at audible frequency, combined with telegraphic keying. Ty~ .AS: Continuous waves modulated by speech or bY' music. Contmuous waves, the amplitude or frequency of which JS varied according to the characteristic vibrations of speech or music. (3) The above classification, into waves of Type3 AI, A2, and A3, shall not prevent the use, under conditions fixed by the Administra- tions concerned, of modulated and/or manipulated waves, by methods not falling within the definitions of Types AI, A2, and A3. (4) These definitions do not relate to systems of transmitting appa- ratus. (5) Waves will be designated in the first place by their frequency in kilocycles per second (kc/s). Following this designation there will be indicated in parentheses, the approximate length in meters. In the present Regulations, the approximate value of the wave length in meters is the quotient of the number 300,000 divided by the frequency expressed in kaocycles per second. §2. Waves emitted by a station must be maintained upon the authorized frequency, as exactly as the state of the art permits, and their radiation must also be as free as practicable from all emissions not essential to the type of communication carried on. §3. The interested administrations shall fix the tolerance allowed between the mean frequency of emissions and the recorded frequency;. they shall endeavor to take advantage of technical improvements progressively to reduce this tolerance. §4. The width of a frequency band occupied by the emission of a station must be reasonably consistent with good current engineering practice for the type of communication involved. §5. In cases where frequency bands are assigned to a specified service, stations in that service must use frequencies sufficiently remote from the limits of these bands, so as not to produce serious interference with the work of stations belonging to services to which are allocated immediately neighboring frequency bands. ARTICLE 5 orA¥=~~clesan~w~:: .Allocation and use of frequencies (wave lengths) and types of emission lengths) and types of ••• ••• emISsion. §1. The AdmmJstratlOns of the contractmg countnes may assIgn any frequency and any type of wave to any radio station within their jurisdiction upon the sole condition that no interference with any service of another country will result therefrom. §2. These Administrations, however, agree to assign to stations, which by their nature are believed capable of causing serious inter- national interference, frequencies and types of waves in conformity with the rules for allocation and use of waves as set forth below. §3. The Administrations agree also to consider the table of alloca- tion of frequency bands (see section 7) as a guide giving, for the different services, the limits which must be observed by all new stations and to which thel. shall adapt all existing stations with the least practicable delay, without diminishing the quality of the serv- ice which these existin~ stations carry on and taking into account the present state of the.lI' installations. §4. Nevertheless, the frequencies of all broadcasting stations now working on frequencies below 300 kc/s (wave lengths above 1,000 m.) shall, in principle, not later than a year after the present Regulations become effective, be removed either to the band included between 160 and 224 kc/s (wave lengths 1,875-1,340 m.) or to the band in- cluded between 550 and 1,500 kc/s (wave 16ngths 545-200 m.).
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