The band 1,500 to 6,000 kc is suitable for regional services and is subject to regional agreements. It is within this band that high frequencies should, in general, be assigned for national services, subject to regional agreements. It is recognized that interference between regions may occur during short periods of each night.

In the portion of the frequency spectrum above 6,000 kilocycles, it is technically feasible for more than one station to operate in the same station-band, without creating international interference, at least for limited times of the day, provided advantage can be taken of such factors as the following:

(1) Differing transmission characteristics in the sunlit and dark portions of the globe;

(2) Differences in time during which operation takes place; (3) Different relative locations of transmitting- and receivingsystems;

(4) Directional characteristics of transmitting or receivingsystems;

(5) Distance-frequency transmission characteristics.

Consequently, the registration of more than one station in a given station-band is recognized as admissible, the production of international interference being a technical question of fact to be considered separately in each case.

The following classes of registration may be established:

(a) Primary registration.-The primary registration of a frequency assignment entitles a station to such full use of the assigned frequency as is provided for by the International Radio Convention.

(b) Secondary registration.-The secondary registration of a frequency assignment in an occupied station-band may be made as such and entitles such a station to the use of this frequency assignment in such manner as to prevent so far as practicable interference with international services carried on by the station having the primary registration.

(c) Local registration. Local registrations in an occupied stationband may be made as such entitling such stations to the use of this frequency assignment to the extent that no interference is caused to the services carried on by stations having either the primary or the secondary registration.

Registration of a frequency assignment at Berne shall become void two years after the date of registration, unless the station has been put into regular active operation prior to that time, provided, however, that no registration shall become void prior to January 1, 1931.

Primary registrations in the fixed service bands above 6,000 kc shall be restricted to stations for long distance communication in excess of 2,000 miles.

Stations requiring bands wider than the standard station-bands, such as, for example, those employed (at some frequencies) for facsimile telegraphy, multiplex, speech telephony, music telephony or television, shall be registered as being of the class of service to which they belong and as to the width of the communication band.

4. Service Assignments in Shared Bands and Assignment of High Frequencies for Aircraft, Criminal Police and Mobile Calling Frequencies

(a) Shared bands.-In the low-frequency shared bands and in the high-frequency shared bands between 1,500 and 6,000 kc, the division between services should be subject to regional agreements.

In connection with regional agreements as to shared bands, care should be taken that mobile stations which do not remain in their own region use only such mobile frequencies as are common to all regions, and it is suggested that there should be reserved certain bands for mobile stations which will be standard in each regional agreement. The bands listed below are recommended as a minimum:

3,400 to 3,500 kc

4,100 to 4.200 kc

4,750 to 4,800 kc

5,500 to 5,700 kc

In the high-frequency bands between 6,000 and 23,000 kc, specified by the International Radiotelegraph Convention of Washington, 1927, for shared mobile and fixed services, it is recommended that, in general, each shared band be divided equally between fixed and mobile services, due regard being given to existing stations in such a division, and that, furthermore, the mobile assignments in this shared band shall be limited to land stations in the mobile service and shall not be given to the actual mobile stations.

In the high-frequency bands above 23,000 kc specified by the International Radiotelegraph Convention of Washington, 1927, for shared services, it is recommended that no consideration be given at this time to a division between services.

(b) High frequencies for aircraft.-In the bands below 6,000 kc, the waves reserved exclusively for aircraft shall be those reserved in the International Radiotelegraph Convention of Washington, 1927, and such others as may be reserved exclusively by regional agreements. It is recommended that in the band above 6,000 kc, the frequencies between 6,150 and 6,400 kc be reserved exclusively for aircraft. In other bands, aircraft should use the frequencies assigned to mobile services on the same basis as ships.

(c) High frequencies for criminal police.-It is recommended that high-frequency assignments for the use of the criminal police

be made the subject of regional agreements in the band 1,500 to 6,000 kc.

(d) Mobile calling frequencies.-The following high frequencies are recommended for ship and aircraft calling frequencies: 5,525, 11,050, 16,575 and 22,100 kc. It is to be noted that they are in exact harmonic relation.

5. Frequency Allocation Plan for Telephony in the Mobile Service

It is recognized that there is need for the working out of an adequate allocation plan under which the various administrations may make frequency assignments for radiotelephone communication in the mobile service. In order to meet the requirements of this service adequately, the plan of allocation should provide coordination between the shore and the ship telephone-frequencies and between these frequencies and those used for marine radiotelegraph service.

It is desirable, for example, to carry on two-way telephony on a ship simultaneously with either one-way or two-way telegraphy. To accomplish this without unreasonable apparatus requirements, certain relationships must be maintained between the transmitting frequencies both on ship and on shore for both telegraphy and telephony.

In order to meet the distance requirements, it is necessary that such a plan provide for assignments in bands which are suitable for successively greater distances of transmission. The bands available are those above 1,500 kc, which, under the Washington Regulations, are allocated to mobile service, and, in addition, certain of the bands which are allocated for joint use by mobile and fixed services. See further discussion given in Annex 6.1

6. Assignment of High Frequencies for National Services

1. It is recommended that the frequencies between 1,500 and 6,000 kilocycles be, in general, used for national services subject to regional agreements, as suggested in Section V. 3, particularly the eighth paragraph.

2. Additional frequency assignments for national services may be made by taking advantage of secondary and local registrations above 6,000 kc, especially between 6,000 and 9,000 kc. Section V. 1. a, relative to the maximum use of frequencies, and Section V. 3, on standard allocation practice, indicate the manner in which this may be accomplished.

VI. AMATEURS

1. General Amateur Regulations

It is recommended that each administration continue to make for itself whatever regulations seem necessary and appropriate for amateur stations within the limiting provisions of the International Radiotelegraph Convention of Washington, 1927. Section 18 of Article 5 and Article 6 of the General Regulations annexed to this Convention provide that each administration shall determine for itself, within the limiting provisions of the Convention and the Regulations, the frequencies and power to be used by amateurs and the technical and operating abilities to be required of licensees. Conditions vary in different administrations and the number of amateurs and their activity also vary. Therefore, each administration should make such regulations as are necessary and in accord with its policy. It is recommended that the controlling principle in the regulation of amateur stations be the regulation of the effect of their emissions. Inasmuch as amateur stations are assigned service bands and not specific single frequencies, it is not necessary for these stations to be equipped to attain that precision of frequency setting or that stability of frequency which are required of stations of other classes. Within the limits of regulations made by each administration, amateur stations should be free to experiment and change apparatus at will, provided only their emissions are confined to the service bands authorized for amateurs and they otherwise comply with regulations governing their power, proficiency of operator, nature of correspondence, etc.

2. Amateur Frequency-bands

It is recommended that the whole width of the frequency-bands, 7,000-7,300 and 14,000–14,400 kc, assigned exclusively to amateur use in the General Regulations of the International Radiotelegraph Convention of Washington, 1927, and the bands, 28,000-30,000 kc and 56,000-60,000 kc, assigned jointly to amateur and experimental use, be made available for the operation of amateur stations. It is felt that the provisions of Section 5 of Article 4 of the General Regulations operate satisfactorily to put upon such stations the obligation of operating at sufficient distance from the limits of such bands so as not to produce interference with adjacent services.

It is recommended that the question of amateur frequency assignments in the bands 3,500-4,000 kc and 1,715-2,000 kc be the subject of regional agreements.

3. Amateur Correspondence

It is recommended that amateur stations be permitted to transmit, on behalf of third parties, communications which are of the same class as the amateur is permitted, by the regulations of his administration, to handle on his own behalf.

Although agreeing in principle that the correspondence of amateur stations should be confined to similarly licensed stations, it is recommended that the amateur regulations of each administration be so drafted as to permit exceptions in time of emergency, in the case of expeditions and small craft not equipped to communicate with commercial or government stations, and for testing with government and commercial stations at the initiative of the latter.

VII. TRANSMITTER INTERFERENCE

1. Harmonics and Other Superfluous Radiation

The reduction of radiation at frequencies outside of the "communication-band" may be considered in two parts: (1) the radiation which takes place on frequencies in the immediate vicinity of the communication-band; and (2) the radiation which takes place at frequencies widely separated from the assigned frequency, notably harmonics. The first of these aspects is treated in Section IV. 1, of this discussion.

In dealing with the second aspect it is necessary to consider harmonic radiation and also any other unauthorized or superfluous radiation at frequencies not in the vicinity of the communication-band.

It is technically possible to reduce all harmonic radiations to such an extent that they are below the noise level of receivers located at distances greater than five miles from the transmitter. The art of transmitter design in the high-frequency region is relatively new but rapid progress is being made and harmonic radiations are being reduced as the congestion in the various services requires. The transmitting-stations in this part of the spectrum must meet in the very near future the same requirements as the lower-frequency stations.

In order to give a concrete expression to the statement above concerning the possibility of harmonic reduction, the following proposals are submitted as being applicable at the present time:

(a) Fundamental frequency below 550 kc.-The field intensity of any harmonic radiation shall not be greater than 0.1 per cent of the fundamental field intensity and not exceed 300 microvolts per meter at a distance of 10 miles from the station.