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History of Communications-Electronics in the United States Navy, Captain Linwood S. Howeth, USN (Retired), 1963, pages 605-610:


Appendix  N.  Extracts  from  the  Fourth  International  Radio-Telegraphic  Convention


ARTICLE  1.  SCOPE

1. The contracting Governments undertake to apply the provisions of the present Convention to all radio communication stations established, managed, or operated by the contracting Governments, and open to the international service of public correspondence. They also undertake to apply these provisions to the special services covered by the regulations annexed to the present Convention.
    2. They also undertake to take or to propose to their respective legislatures the necessary measures to impose the observance of the provisions of the present Convention and the Regulations annexed thereto upon individuals and private enterprises authorized to establish and operate radio communication stations in international service, whether or not open to public correspondence.
    3. The contracting Governments recognize the right of two contracting countries to organize between themselves radio communications, provided only that they conform to all provisions of the present Convention and the Regulations annexed thereto.

ARTICLE  8.  INTERFERENCE

The stations covered by Article 1 must, so far as practicable, be established and operated under the best conditions known to practice and must be maintained abreast of scientific and technical progress.
    All stations, whatever their purpose, must so far as practicable be established and operated in such a way as not to interfere with the communications or radio services of other contracting Governments and of individuals or of private enterprises authorized by these contracting Governments to carry on public radio communication service.

ARTICLE  9.  PRIORITY  FOR  DISTRESS  CALLS

Radio stations engaged in the mobile service shall be obliged to give absolute priority to distress calls, regardless of their origin, to answer such calls, and to take such action with regard thereto as may be required.

ARTICLE  21.  RESERVATION  AS  TO  NONREGULATED  STATIONS

The contracting Governments retain their entire liberty regarding radio installations not covered in Article 1, and particularly to naval and military installations.
    All these installations and stations must, so far as practicable, comply with the provisions of the regulation relative to the relief to be given in case of distress and to measures to be taken to prevent interference. They must also, so far as practicable, observe the provisions of the regulations concerning the types of waves and frequencies to be used, according to the type of service which these stations carry on.
    When these installations and stations, however, exchange public correspondence or participate in special services governed by the Regulations annexed to the present Convention, they must, in general, conform to the provisions of the Regulations for the execution of these services.

EXTRACTS  FROM  GENERAL  REGULATIONS  ANNEXED  TO  THE  INTERNATIONAL  RADIOTELEGRAPH  CONVENTION

ARTICLE  4.

1. Radio emissions are divided into two classes:
    A. Continuous waves,
    B. Damped waves,
defined as follows:
    CLASS  A. Waves the successive oscillations of which are identical under permanent conditions.
    CLASS  B. Waves consisting of successive wave trains in which the amplitude of the oscillations, after having reached a maximum, decreases gradually.
    Waves of Class A include the following types which are defined below:
    Type A1: Unmodulated continuous waves. Continuous waves, the amplitude or frequency of which is varied by means of telegraphic keying.
    Type A2: Continuous waves modulated at audible frequency. Continuous waves the amplitude or frequency of which is varied in a periodic manner at audible frequency, combined with telegraphic keying.
    Type A3: Continuous waves modulated by speech or by music. Continuous waves, the amplitude or frequency of which is varied according to the characteristic vibrations of speech or music.
    The above classification, into waves of Types A1, A2, and A3, shall not prevent the use, under conditions fixed by the administrations concerned, of modulated and (or) manipulated waves, by methods not falling within the definitions of Types A1, A2, and A3.
    These definitions do not relate to systems of transmitting apparatus.
    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, an approximate value of the wave length in meters is the quotient of the number 300,000 divided by the frequency expressed in kilocycles per second.
    2. Waves emitted by a station must be maintained upon their authorized frequency, as exactly as the state of the art permits, and their radiation must 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.
    4bix. 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.
    4. 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 bands of frequencies.

ARTICLE  5.  ALLOCATION  AND  USE  OF  FREQUENCIES  (WAVE  LENGTHSAND  TYPES  OF  EMISSIONS

    1. The Administrations of the contracting countries may assign any frequency or any type of wave to any radio station within their jurisdiction upon the sole condition that it will result in no interference with any service of another country.
    2. These Administrations, however, agree to assign to stations, which by their very nature are believed capable of causing serious international 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 allocation of frequency bands (see par. 7) as a guide giving, for the different services, the limits which must be observed by all new stations and to which they shall adapt all existing stations with the least practicable delay, without diminishing the quality of the service which these existing stations carry on and taking into account the present state of their 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, within a year following the coming into force of the present regulations, be removed either to the band included between 160 and 224 kc/s (wave lengths 1,875-1,340 m.) or to the band included between 550 and 1,500 kc/s (wave lengths 454-200 m.).
    5. No new broadcasting station shall be authorized to work in the frequency band included between 160 and 224 kc/s (wave lengths 1,875-1,340 m.) unless no inconvenience therefrom will result to existing radio communication services, including broadcasting services carried on by the stations which are already using the frequencies included in this band and stations the frequencies of which shall be removed to the interior of this same band in conformity with the provision of paragraph 4 above.
    6. The power of existing broadcasting stations using frequencies below 300 kc/s (wave lengths over 1,000 m.) shall not be increased unless no inconvenience will result to existing radio communication services.
    7. The table below shows the allocation of frequencies (approximate wave lengths) among the various services:
    8. (1) Use of waves of Type B of a frequency of less than 375 kc/s (wave length over 800 m.) will be forbidden beginning January 1, 1930, with the exception provided in paragraph 1 of the present Article except for existing land stations.
        (2) No new installations of transmitters of waves of Type B shall be made in ships or in aircraft beginning January 1, 1930, except when these transmitters working on full power shall dissipate less than 300 watts measured at the input of the supply transformer at audible frequency.
        (3) The use of waves of Type B of all frequencies will be forbidden beginning January 1, 1940, except for transmitters fulfilling the conditions as to power indicated in (2) above.
        (4) No new installations of transmitters of Type B shall henceforth be made in a land or fixed station. Waves of this type shall be forbidden in all land stations beginning January 1, 1935.
    9. The use of waves of Type A3 shall not be authorized between 100 and 160 kc/s (3,000 and 1,875 m.).
    10. The use of waves of Type A2 shall not be authorized between 100 and 150 kc/s (3,000 and 2,000 m.), except in the band of 100-125 kc/s (3,000-2,400 m.), for time signals exclusively.
    11. In the band 460-550 kc/s (650-545 m.) no type of emissions likely to render inoperative the signals of distress, of alarm, of security, of urgency sent on 500 kc/s (600 m.) shall be authorized.
    12. In principle every station carrying on a service between fixed points on a wave of frequency below 10 kc/s (wave lengths over 2,725 m.) must use a single frequency chosen from the bands allocated to that service (par. 7 above), for each of the transmitters which it possesses and which are capable of simultaneous operation. A station shall not be permitted to use, for a service between fixed points, a frequency other than that allocated, as stated above.
    13. In principle stations shall employ the same frequencies and the same types of emission for the transmission of messages by the one-way system as for their normal service. Regional arrangements may be made, however, with a view to exempting stations concerned from this rule.
    14. With a view to facilitating the exchange of synoptic meterological messages in European regions, two frequencies between 37.5 and 100 kc/s (wave lengths of 8,000-3,000 m.) shall be allocated to this service by regional arrangements.
    15. To facilitate transmission and rapid distribution of information of value in the detection of crime and pursuit of criminals, a frequency between 37.5 and 100 kc/s (wave length 8,000-3,000 m.) shall be reserved for this purpose by regional arrangements.
    16. The frequencies assigned by Administrations to all new fixed land or radio broadcasting stations which they may have authorized or of which they may have undertaken the installations must be chosen in such a manner as to prevent as far as possible interference with international services carried on by existing stations the frequencies of which have already been notified to the International Bureau. In a case of change of frequency of an existing fixed land or broadcasting station, the new frequency assigned to this station must comply with the above conditions.
    The interested Governments shall agree, in case of need, upon the fixing of waves to be assigned to the stations in question as well as upon the conditions for the use of waves so assigned. If no arrangement intended to eliminate interference can be arrived at, the provisions of Article 18 of the Convention may be applied.
    17. Each Administration shall advise the International Bureau without delay when it decides upon or authorizes the establishment of a radio communication station, the operation of which necessitates the assignment for its regular service, of a particular frequency below 37.5 kc/s (of a wave length above 8,000 m.) in the case where the use of this frequency might cause international interference over broad areas. This notice must reach the International Bureau four months before the construction of the station contemplated so as to take care of objections which any of the administrations might raise against the adoption of the proposed frequency.
    In the case of a fixed short wave station intended to carry on a regular service and the radiation of which is likely to cause international interference, the Administration concerned must, as a general rule, before the completion of a station and in any case before it is open for service, advise the International Bureau of the frequency assigned to the station.
    Such a notification shall, however, be sent only when the Administration concerned shall have ascertained that the service in question can be established within a reasonable time.
    18. Each Administration may assign to amateur stations frequencies chosen from the band allocated to amateurs in the allocation chart (par. 7 above).
    The maximum power which these stations may use shall be fixed by the administration concerned taking into account the technical abilities of the operators and the conditions under which the stations must function.
    All the general rules fixed in the Convention and in these Regulations apply to amateur stations. In particular, the frequency of the waves emitted must be as constant and as free from harmonics as the state of the art permits.
    In the course of their transmission these stations must transmit their call signals at frequent intervals.

ARTICLE  18.  CONDITIONS  TO  BE  OBSERVED  BY  MOBILE  STATIONS

1. Mobile stations must be established in such a way as to conform, with reference to frequencies and types of waves, with the general provisions constituting the subject matter of Article 5. In accordance with these provisions, the use by mobile stations of damped waves (Type B) of a frequency below 375 kc/s (wave length above 800 m.), shall be forbidden beginning January 1, 1930.
    In addition, no new installations of transmitters of Type B waves shall be made in mobile stations after January 1, 1930, except when these transmitters working on full power shall expend less than 300 watts measured at the input of the supply transformer at audible frequency.
    Finally, the use of Type B waves of all frequencies shall be forbidden beginning January 1, 1940, with the exception of transmitters fulfilling the same conditions regarding power as above.
    2.  Every station installed on board a vessel or an aircraft following a maritime route, such vessel or aircraft being compulsorily equipped with radio apparatus in accordance with an international agreement, must be able to send and receive on a wave of 500 kc/s (600 m.) type A2 or B.
    Ship stations must, in addition, be able to use the wave of 375 kc/s (800 m.), type A2 (or B subject to paragraph 1 above).
    Aircraft stations must be able to send and receive the wave of 333 kc/s (900 m.) Types A2 or A3 (or B subject to the provisions of Paragraph 1 above).
    3. In addition to the fixed waves stipulated above, mobile stations equipped for the sending of waves of Types A1, A2 or A3 may use all the waves authorized in Article 5.
    The use of waves of Type B is authorized only for the following frequencies (wave lengths):
 
Kc/s    Meters          Kc/s    Meters
375    800 500    600
410    750 665    450
425    705 1000    300
454    660 1364    220

The use of the Type B wave of 665 kcs (450 m.) is forbidden from now on in regions where this wave may interfere with broadcasting.
    The use of the type B wave of 1000 kcs (300 m.) for traffic is forbidden, from now on, between 6:00 p.m. and midnight, local time, and shall be entirely forbidden, at all times, beginning January 1, 1930 at the latest. This same Type B wave of 100 kcs (300 m.) may, however, continue in use indefinitely without restriction as to hours, by stations on board fishing vessels, for radiocompass bearings between one another, on condition of not interfering with broadcasting.
    4. All apparatus in mobile stations established for the transmission of waves of Type A between 125 and 150 kcs (2400-2000 m.) must permit the use of at least three frequencies chosen from this band, and must permit a rapid change from one to another of these frequencies.
    5. All stations on ships compulsorily equipped with radio apparatus must be able to receive the wave of 500 kcs (600 m.) and in addition all the waves necessary to the proper accomplishment of their services.
    Beginning January 1, 1932 they must be able to receive easily and efficiently on the same frequencies, waves of Types A1 and A2.
    6. Transmitting apparatus used in the mobile service must be provided with devices permitting reduction of power. This provision does not apply to transmitters, the input power of which does not exceed 300 watts.
    7. Receiving apparatus must be such that the current which it produces in the antenna shall be as small as possible and will not disturb neighboring stations.
    8. The transmitting and receiving apparatus of all mobile stations must be such as to allow changing of frequency as rapidly as possible. All installations must be such that communications once being established the time necessary to change from transmission to reception and vice versa will be as short as possible.

ARTICLE  19.  CALLING  AND  LISTENING  WAVES

1. In the band included between 360 and 515 kcs (830 and 580 meters) the only waves of type B allowed are the following: 375, 410, 425, 454, and 500 kcs (800, 730, 705, 660, 600 m).
    The general calling wave, which must be used by all ships compulsorily equipped and by coast stations, is 500 kcs (600 m) (A1, A2 or B).
    Besides the frequency 500 kcs (600 m) the use of waves between 485 and 515 kcs (620 and 580 m) is forbidden, of any type.
    The frequency of 500 kcs (600 m) is the international calling and distress. It may be used, but with discretion for other purposes, if it does not interfere with distress, urgent, safety, or call signals.
    Coast stations must be able to use at least one wave besides that of 500 kcs (600 m). This additional wave shall be underlined in the Nomenclature to indicate that it is the normal working wave of the station. The additional waves thus chosen may be the same as those of ship stations or may be different. In any case, the working waves of the coast stations must be chosen in such a way as to avoid interference with neighboring stations.
    Besides the normal working waves underlined in the Nomenclature, coast and ship stations may use additional waves in the authorized band as they consider convenient. These waves shall be published in the Nomenclature without being underlined.
    4. (1) In order to increase safety of life at sea (ships) and above the sea (aircraft), all stations in the mobile maritime service must, during their hours of service, take the necessary measures to assure the watch on the distress wave (500 kcs-600 m) twice per hour for three minutes, beginning at the 15th minute and at the 45th minute after each hour Greenwich Mean Time.
        (2) Stations carrying on a service of radiotelegraph correspondence, press news, etc., with ships at sea must observe silence during the intervals indicated above. Only the transmissions provided for in Article 21, Paragraphs 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 subparagraph (1) of the present paragraph.
    6. The following rules shall be observed in the operation of stations in the mobile service using waves of type A1 in the band 100 to 160 kcs (3000 to 1875 m) which is assigned to the mobile service.
        (a) Every coast station carrying on communication on a long continuous wave must listen on the wave of 143 kcs (2100 m) unless it is otherwise indicated in the Nomenclature. The coast station shall transmit all its traffic on the wave or waves which are especially assigned to it.
        (b) When a mobile station desires to establish communication on a long continuous wave with another station of the mobile service, it must employ the frequency of 143 kcs (2100 m) unless it is otherwise indicated in the Nomenclature. This wave, designated as the general 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 having established communication with another station in the mobile service, on the general communication wave, 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 continuous waves and not engaged in communication on another wave, must, in order to permit the exchange of traffic with other stations of the mobile service, return to the wave of 143 kcs (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) Coast stations shall transmit their traffic lists at specified times, published in the Nomenclature, on the wave or waves which are assigned to them.
        Besides the times thus fixed for this transmission of their traffic lists, coast stations may 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 kcs (2100 m) in areas where there is no congestion of traffic.
        (f) The special provisions concerning the service carried on by land stations using long continuous waves shall be shown in detail in a special reference in the Nomenclature.

FREQUENCY  ASSIGNMENTS  BY  SERVICE
Frequencies in
kilocycles per
second
 Services
10-100  Fixed services.
100-110  Fixed services and mobile services.
110-125  Mobile services.
125-1501  Maritime mobile services for public correspondence exclusively.
150-160  Mobile services:
    (a) Broadcasting.
    (b) Fixed services.
    (c) Mobile services.
160-194  The conditions for use of this band are subject to the following regional arrangements:
    All regions where broadcasting stations now exist working on frequencies below 300 kc./secs broadcasting.
    Other regions fixed and mobile services. Regional arrangements will respect the rights of other regions in this band.
    The conditions for use of this band are subject to the following regional arrangements:
    (a) Air mobile service exclusively.
    (b) Air fixed services exclusively.
    (c) Within the band 250-285 kc.
194-285  Europe. (1200-1050 m.) Fixed service not open to public correspondence.
Other regions:
    (a) Mobile services except commercial ship stations.
    (b) Fixed air services exclusively.
    (c) Fixed services not open to public correspondence.
285-315  Radio beacons.
315-3502  Air mobile services exclusively.
360-390  Mobile services not open to public correspondence:
    (a) Radio direction finding.
    (b) Mobile services, on condition that they do not interfere with radio direction finding.
390-460  Mobile services.
460-485  Mobile services (except damped waves and radiotelephony).
485-5153  Mobile services (distress, call, etc.).
515-550  Mobile services not open to public correspondence (except damped waves and radiotelephony).
550-1,3004  Broadcasting.
1,300-1,500      (a) Broadcasting.
    (b) Maritime mobile services, waves of 1365 kc./sec. (220 m) exclusively.
1,500-1,715  Mobile services.
1,715-2,000  Mobile services.
Fixed services.
Amateurs.
2,000-2,250  Mobile services and fixed services.
2,250-2,750  Mobile services.
2,750-2,850  Fixed services.
2,850-3,500  Mobile services and fixed services.
3,500-4,000  Mobile services.
Fixed services.
Amateurs.
4,000-5,500  Mobile services and fixed services.
5,500-5,700  Mobile services.
5,700-6,000  Fixed services.
6,000-6,150  Broadcasting.
6,150-6,675  Mobile services.
6,675-7,000  Fixed services.
7,000-7,300  Amateurs.
7,300-8,200  Fixed services.
8,200-8,550  Mobile services.
8,500-8,900  Mobile services and fixed services.
8,900-9,500  Fixed services.
9,500-9,600  Broadcasting.
9,600-11,000  Fixed services.
11,000-11,400  Mobile services.
11,400-11,700  Fixed services.
11,700-11,900  Broadcasting.
11,900-12,300  Fixed services.
12,300-12,825  Mobile services.
12,825-13,350  Mobile services and fixed services.
13,350-14,000  Fixed services.
14,000-14,400  Amateurs.
14,400-15,100  Fixed services.
15,100-15,550  Broadcasting.
15,350-16,400  Fixed services.
16,400-17,100  Mobile services.
17,100-17,750  Mobile services and fixed services.
17,750-17,800  Broadcasting.
17,800-21,450  Fixed services.
21,450-21,550  Broadcasting.
21,550-22,300  Mobile services.
22,300-23,000  Mobile services and fixed services.
23,000-28,000  Not reserved.
28,000-30,000  Amateurs and experiments.
30,000-56,000  Not reserved.
56,000-60,000  Amateurs and experiments.
Above 60,000  Not reserved.

    1The wave of 143 kc./s (2,100 m.) is the calling wave for mobile stations using long continuous waves.
    2The wave of 333 kc./sec. (900 m.) is the international calling wave for air services.
    3The wave of 500 kc./sec. (600 m.) is the international calling and distress wave. It may be used for other purposes on condition that it will not interfere with call signals and distress signals.
    4Mobile services may use the band 550 to 1,300 kc./sec. (545-230 m.) on condition that this will not cause interference with the services of a country which uses this band exclusively for broadcasting.
    NOTE: It is recognized that short waves (frequencies from 6,000 to 23,000 kc./sec., approximately--wave lengths from 50 to 13 m. approximately) are very efficient for long-distance communications. It is recommended that, as a general rule, this band of waves be reserved for this purpose, in services between fixed points.
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