Radio Service Bulletin, May 1, 1922, pages 23-30:

REPORT  OF  DEPARTMENT  OF  COMMERCE  CONFERENCE  ON  RADIO  TELEPHONY.

    This conference was called by Secretary Hoover to consider general questions concerning the regulation of radio communication.
    The following were invited to serve as members of the conference, the representatives of the Government departments being selected by their several departments:
    Dr. S. W. Stratton, chairman (Director of Bureau of Standards).
    Edwin H. Armstrong, Columbia University, New York, N. Y.
    Capt. Samuel W. Bryant, U. S. N., Navy Department.
    D. B. Carson, Commissioner of Navigation, Department of Commerce.
    J. C. Edgerton, Superintendent Radio Service, Post Office Department.
    Dr. Alfred N. Goldsmith, secretary Institute of Radio Engineers, New York, N. Y.
    Prof. L. A. Hazeltine, Stevens Institute of Technology, Hoboken, N. J.
    R. B. Howell, Metropolitan Utilities District, Omaha, Nebr.
    Prof. C. M. Jansky, jr., University of Minnesota.
    Hiram Percy Maxim, president American Radio Relay League, Hartford, Conn.
    Maj. Gen. George O. Squier, War Department.
    Representative Wallace H. White, jr., of Maine.
    W. A. Wheeler, Bureau of Markets and Crop Estimates, Department of Agriculture.
    The conference was in session from February 27 to March 2, at the end of which time a tentative report was prepared. This report was sent to all persons who requested it, and to representatives of various interests which in the judgment of the Department of Commerce were interested. A large number of suggestions and comments were received. The conference had subsequent sessions on April 17, 18, and 19. All comments were considered, the general effect of the comments being to approve the substance of the preliminary report with a very few exceptions. The report as finally amended and adopted is given herewith.
    In addition to the preparing a report on technical matters, the conference made recommendations as to essential points required in legislation to give the Secretary of Commerce authority necessary to accomplish the ends recommended, through the power to make and enforce regulations.

General resolutions adopted by the Radio Telephony Conference.

    Resolved, That the Conference on Radio Telephony recommend that the radio laws be amended so as to give the Secretary of Commerce adequate legal authority for the effective control of--
    (1) The establishment of all radio transmitting stations except amateur, experimental, and Government stations.
    (2) The operation of nongovernmental radio transmitting stations.1
    Resolved, That it is the sense of the conference that radio communication is a public utility and as such should be regulated and controlled by the Federal Government in the public interest.
    Resolved, That the types of radio apparatus most effective in reducing interference should be made freely available to the public without restrictions.

I. Allocation of wave bands for radio telephony.

    A. It is recommended that waves for radio telephony be assigned in bands, according to the class of service, as given in the following table.
    Throughout this report, both wave lengths and, wave frequency are given. Wave length in meters is 300,000,000 divided by wave frequency in kilocycles per second.
    Wave bands marked exclusive can be used for no other type of service; those marked nonexclusive are available for other types of radio communication, subject to regulation.
 
Use.Wave
length
(meters).		Wave
frequency
(kilocy-
cles per
second).
  (1) Transoceanic radio telephone experiments, nonexclusive.  (See note 3)
{6,000
5,000
50   
60   
  (2) Fixed service radio telephony, nonexclusive.  (See note 4)
{3,300
2,850
90.9
105.2
  (3) Mobile service radio telephony, nonexclusive.
{2,650
2,500
113.2
120   
  (4) Government broadcasting, nonexclusive.  (See note 1)
{2,050
1,850
146   
162   
  (5) Fixed station radio telephony, nonexclusive.  (See note 5)
{1,650
1,550
181.8
193.5
  (6) Aircraft radio telephony and telegraphy, exclusive.
{1,550
1,500
193.5
200   
  (7) Government and public broadcasting, nonexclusive.
{1,500
1,050
200   
285.7
  (8) Radio beacons, exclusive.  (See note 6.)
{1,050
950
285.7
316   
  (9) Aircraft radio telephony and telegraphy, exclusive.
{950
850
316   
353   
(10) Radio compass service, exclusive.  (See note 7.)
{850
750
353   
400   
(11) Government and public broadcasting, 200 miles or more from the seacoast, exclusive.
{750
700
400   
428   
(12) Government and public broadcasting, 400 miles or more from the seacoast, exclusive.
{700
650
428   
462   
(13) Marine radio telephony, nonexclusive.  (See note 8.)
{750
650
400   
462   
(14) Aircraft radio telephony and telegraphy, exclusive.  (See note 8.)
{525
500
572   
600   
(15) Government and public broadcasting, exclusive.
{495
485
606   
618   
(16) Private and toll broadcasting.  (See note 9.)
{485
285
618   
1,052   
(17) Restricted special amateur radio telegraphy, nonexclusive.  (See note 10.) 310968   
(18) City and state public safety broadcasting, exclusive.  (See note 11.)
{285
275
1,052   
1,091   
(19) Technical and training schools (shared with amateur).  (See note 12.)
{275
200
1,091   
1,500   
(20) Amateur telegraphy and telephony (exclusive, 160 to 200 meters).  (Shared with technical and training schools, 200 to 275 meters.)  (See note 13.)
{275
150
1,091   
2,000   
(21) Private and toil broadcasting, exclusive.
{150
100
2,000   
3,000   
(22) Reserved. 110023,000   
1Below.              2Above.

    NOTE.--The terms used in the above schedule are defined as follows: "Broadcasting" signifies transmission intended for an unlimited number of receiving stations without charge at the receiving end. It includes:
    (1) Government broadcasting, signifying broadcasting by departments of the Federal Government;
    (2) Public broadcasting, signifying broadcasting by public institutions, including State governments political subdivisions thereof, and universities and such others as may be licensed for the purpose of disseminating informational and educational service;
    (3) Private broadcasting, signifying broadcasting without charge by the owner of a station, as a communication company, a store, a newspaper, or such other private or public organization or person as may be licensed for the purpose of disseminating news, entertainment, and other service; and
    (4) Toll broadcasting, signifying broadcasting where charge is made for the use of the transmitting station.
    NOTE 2.--A station carrying on two or more of the broadcasting services specified in classes 2, 3, and 4 must be licensed for each class of service.
    NOTE 3.--When transoceanic radio telephone experiments are to be conducted the Department of Commerce should endeavor to arrange with other countries for the use of the wave band 5,000 to 6,000 meters assigned for this purpose.
    NOTE 4.--The wave band from 2,850 to 3,300 meters may be used for fixed-service radio telephony only provided it does not interfere with service using continuous-wave telegraphy.
    NOTE 5.--The wave, band from 1,550 to 1,650 meters is for use of radio telephone communication over natural barriers, but is not exclusive of other services.
    NOTE 6.--Radio beacons are radio-transmitting stations which transmit signals from which a mobile direction-finding station may determine its bearing or position.
    NOTE 7.--Radio compass service is here used to signify a direction-finding service in which a mobile station transmits to one or more fixed stations which in turn transmit back the bearing or position of the mobile station.
    NOTE 8.--The wave band from 525 to 650 meters is reserved for marine radio telegraphy exclusively.
    NOTE 9.--Assignment of waves in band 16 will, in general, involve keeping the zones from 285 to 315 and from 425 to 475 meters open in coastal regions. Furthermore, in border regions, account should be taken of the wave lengths used in neighboring countries, and these should be suitably protected by a locally unused band of adjacent wave lengths.
    NOTE 10.--The restricted special amateur wave of 310 meters is for use by a limited number of inland stations and only where it is necessary to bridge large, sparsely populated areas or to overcome natural barriers.
    NOTE 11.--City and State public safety broadcasting should in small cities be conducted by interrupting the broadcast service of classes 2, 3, or 4 in case of emergency. In large cities this service will ordinarily have its own stations and will use the wave band 275 to 285 meters assigned to such service. Private detective agencies desiring to operate radio telephone broadcasting service should be required to cooperate with municipal or State services in the use of the wave band 275 to 285 meters, assigned to the latter service.
    NOTE 12.--By "technical and training school" in this report is meant a school which in the judgment of the Secretary of Commerce is carrying on sufficient instruction of the proper character for training men for the radio profession to warrant the granting of a station license for that purpose.
    NOTE 13.--An amateur is one who operates a radio station, transmitting, receiving, or both, without pay or commercial gain, merely for personal interest or in connection with an organization of like interest.
    NOTE 14.--The conference is of the opinion that broadcast transmitting stations should not in coastal regions be permitted on wave lengths closely adjacent to those assigned in the marine traffic and believes that its recommendations provide for adequate protection of such marine traffic. The conference recommends the assignment of wavelengths adjacent to those used in the marine traffic to inland stations under such conditions as to avoid interference with the marine traffic.
    B. It is recommended that the Secretary of Commerce assign a specific wave length to each radio telephone broadcasting station (except Government and amateur stations), this course being within the band pertaining to the particular service of that station.
    C. It is recommended that the wave band assigned to amateurs, 150 to 275 meters, be divided into bands according to the method of transmission, damped wave stations being assigned the band of lowest wave lengths, interrupted or modulated continuous wave radio telegraph stations the next band, radio telephone stations the next band, and finally unmodulated continuous wave radio telegraph stations the band of highest wave lengths. It is recommended that amateurs be permitted to carry on broadcasting within the wave length band assigned by the Secretary of Commerce to amateur radio telephony.
    A damped wave is one composed of successive trains in which the amplitude of the oscillation after having reached its maximum decreases gradually. This refers to waves from spark transmitters or other types of transmitters having characteristic decrement similar to spark transmitters. Transmitters employing continuous wave oscillators in which the variation in frequency or amplitude is abrupt (as with the use of a chopper) are classed as damped wave transmitters.
    An interrupted or modulated continuous wave is one in which the amplitude or the frequency is varied according to a simple periodic law of audible frequency. (This is commonly referred to as the interrupted continuous waves, or I. C. W.) A continuous wave transmitter employing a rectified plate voltage which is not a substantially constant direct voltage is classed as an interrupted or modulated continuous wave transmitter. NOTE.--This included transmitters in which the variation in amplitude or frequency is effected in a gradual way only. (For abrupt variation see damped wave.)
    An unmodulated continuous wave is one in which the permanent state is periodic and has substantially constant amplitude and frequency. (This includes waves in which the amplitude variation is effected simply by the manipulation of a key. This is commonly referred to as a continuous wave, or C. W.)
    D. It is recommended that the present regulations governing experimental station remain in effect. An experimental station is one operated exclusively for technical or scientific investigations.
    E. 1. The conference experienced the greatest difficulty in providing even partly for the generally demanded services. The conference therefore disapproved of the elimination of essential services by the introduction of direct advertising which might be expected to require extensive assignment of wave bands if permitted at all.
    2. Many services for which radio telephony might otherwise be desirable can not practically be conducted by this means on account of the interference which such use would cause with other services of a more essential nature or for which there is great public demand.
    3. In view of the demand for broadcast service by the general public, it is not desirable to disseminate information over wide areas for purposes of point-to-point communication except where that communication can not be effectively maintained by other means.
    4. A radio service in which a message is addressed or intended for a prescribed number of particular stations is not a broadcast service and is to be classed as a "multiple telegram" or "multiple telephone service." It was not thought advisable to use the much demanded short wave bands for communications of this nature, as they would serve a relatively small number. The available wave lengths for such multiple service messages are bands 2 and 5.
    5. The conference is of the opinion that the use of radio communication for "point-to-point" communication over land in most cases constitutes an uneconomic use of the available wave bands and it is recommended that at the present state of the art such communication should be carried on by other means, in so far as possible.
    6. The conference very carefully considered the proximity of wave bands assigned to amateurs and broadcast services, but deemed it essential to utilize all of the available wave bands.
    7. It was felt that waves longer than 275 meters should not be assigned to technical and training school stations because of the needs of broadcast services greatly desired by a large portion of the public in that zone, and because the extension of amateur wave lengths and the organization of their use will enable their effective employment by the technical and training school stations.

II. Power limitation, geographical distribution, and hours of operation of broadcasting stations.

    A. It is recommended that the Secretary of Commerce assign to each radio telephone broadcasting station a permissible power based on the normal range of the station, such normal ranges for the different classes of service to have the following average values, larger or smaller values being discretionary where conditions warrant:
            Government broadcasting stations, 600 (land) miles.
            Public broadcasting stations, 250 miles.
            Private and toll broadcasting stations, 50 miles.
    Normal range is the average reliable daytime ranges over which satisfactory communication can be obtained with good available receiving apparatus.
    The conference recommends that broadcasting stations should not be allowed to use unlimited power because of the fact, that this will limit the number of services which can be rendered within a given area to an undesirable extent.
    (NOTE.--The Bureau of Standards of the Department of Commerce should make a study of the relation between the normal reliable range of a station and the antenna power on the basis of the use of good available receiving apparatus. It is recognized that this relation may change with the development of the radio art.)
    B. It is recommended that the same wave (or overlapping wave bands) not be assigned to stations within the following distances from one another, except that these distances may be lowered if the normal ranges of the stations are correspondingly lowered:
            For Government broadcasting stations, 1,500 miles.
            For public broadcasting stations, 750 miles.
            For private and toll broadcasting stations, 150 miles.
    (NOTE.--The Bureau of Standards should make a study of the width of wave band (expressed in cycles per second) required for satisfactory radio telephony. It is recognized that this width depends on the methods of transmission and reception employed.)
    C. It is recommended that the Secretary of Commerce cause an immediate study to be made of the best geographical distribution of broadcasting stations with the view of attaining the best service with a minimum of interference.
    D. It is recommended that in cases where congestion of radio telephone broadcasting traffic exists, or threatens to exist, the Secretary of Commerce assign suitable hours of operation to existing or proposed radio telephone broadcasting stations.

III. Considerations to be followed in granting licenses.

    A. It is recommended that in the case of conflict between radio communication services first consideration be given to the public not reached, or not so readily reached, by other communication services.
    B. It is recommended that subject to public interest and to the reasonable requirements of each type of service the order of priority of the services be Government, public, private, toll.
    C. It is recommended that the degree of public interest attaching to a private or toll broadcasting service be considered in determining its priority in the granting of licenses, in the assignment of wave frequencies, and in the assignment of permissible power and operating time, within the general regulations for these classes of service.
    D. It is recommended that toll broadcasting service be permitted to develop naturally under close observation, with the understanding that its character; quality, and value to the public will be considered in determining its privileges under future regulations.
    E. It is recommended that direct advertising in radio broadcasting service be absolutely prohibited and that indirect advertising be limited to a statement of the call letters of the station and of the name of the concern responsible for the matter broadcasted, subject to such regulations as the Secretary of Commerce may impose.
    F. It is recommended that when all available wave frequencies in any geographical region are already assigned, no further licenses for broadcasting be granted in that region until cause arises for the revocation of existing licenses.
    G. It is recommended that private or toll broadcasting stations transmitting time signals shall transmit only official time signals and with authorization from and under conditions approved by the Secretary of Commerce.
    H. It is recommended that the transmission of signals of such character or wave length as to deliberately interfere with the reception of official time signals constitutes grounds for the revocation of suspension of the transmitting station or operator's license.
    I. It is recommended that license requirements for the operator of a radio telephone transmitting station include a knowledge of radio transmitting and receiving apparatus and of the International Morse Code, sufficient to receive at a rate of not less than 10 words per minute.
    J. It is recommended that the establishment at any later date of any commercial transmitting stations having more than 1 kw. input to the antenna may, at the discretion of the Secretary of Commerce, be prohibited within 25 land miles of a Government or commercial station or in regions where congestion of radio traffic shall warrant such prohibition.
    K. It is recommended that the sharpness of the emitted wave of the transmitting station affect the privileges extended to such station.

IV. Recommendations relative to the amateur.

    A. It is recommended that the status of the amateur be established by law and that the limits of the wave band allotted to the amateur as given above in section I be specified in the law.
    B. It is recommended that the amateur continue to be under the jurisdiction of the Department of Commerce.
    C. It is recommended that for the purpose of self-policing among the amateurs, amateur deputy radio inspectors be created, elected from their number of the amateurs of each locality; that upon receipt of notice of such election the radio inspector in charge of the district in which such amateurs are located shall appoint the person chosen a deputy radio inspector, serving without compensation or for the sum of $1 per year if compensation is legally required; that the duty of such amateur deputy inspector shall be to endeavor to the best of his ability to accomplish under the direction of the district radio inspector, observance of the Radio Communication Laws and the Regulations of the United States and the observance of such local cooperation of measures as are agreed to in each community for the minimization of interference between the various groups of the public interested in radio; that such amateur deputy inspectors be clothed with whatever authority may be necessary in the opinion of the district radio inspector.

V. Technical methods for the reduction of interference.

    A. It is recommended that the Secretary of Commerce at his discretion prohibit at any time the use of existing radio transmitting apparatus and methods which result in unnecessary interference, provided that such action should not be taken unless more satisfactory apparatus and methods are commercially available at reasonable prices and until an adequate time interval is allowed for the substitution of the more satisfactory apparatus.
    B. It is recommended that the Secretary of Commerce at his discretion prohibit at any time the use of existing radio receiving apparatus which cause the radiation of energy, provided that such action should not be taken unless more satisfactory apparatus and methods are commercially available at reasonable prices and until an adequate time interval is allowed for the substitution of the more satisfactory apparatus.
    NOTE.--"Certain forms of oscillating receivers cause the feeble radiation of continuous waves and may therefore be a source of local interference."
    C. It is recommended that the Bureau of Standards make a study of the technical methods for the reduction of interference, with a view to publishing their findings, giving special attention to the following:
    (1) The reduction of the rate of building up (increment) of oscillations in radiating systems. (This rapid building up of oscillations occurs in damped wave and interrupted continuous wave transmitters, and may, of course, be eliminated by the substitution of other types of transmitters. It may, however, be reduced in these types by proper circuit arrangements.)
    (2) The reduction of harmonics in continuous wave transmitters and of irregularities of oscillation. ("Mush" in arc transmitters and "swinging" of the frequency in some continuous wave transmitters not employing a master oscillator.) "Mush" signifies small sudden irregularities occurring in the antenna current of arc transmitters. Swinging signifies relativity slow changes in the frequency of a transmitted wave.
    A harmonic of a wave is wave whose frequency is a multiple of that of the given wave. (The wave length of a harmonic is thus a submultiple of the wave length of the given wave.) It is often convenient to include as harmonics frequencies which are dependent on the frequency of the transmitter but which are not exact multiples.
    (3) The comparison of the variable amplitude method with the variable frequency method of continuous wave telegraphy.
    (4) The preferable methods of telephone modulation to avoid changes in the frequency of oscillation.
    (5) The proper circuit arrangements of regenerative (including oscillating) receivers to avoid radiation of energy (as by the use of a radio-frequency amplifier with an untuned antenna or with a coil aerial.)
    (6) The use of highly selective receiving apparatus, including a list of approved forms. NOTE.--A selective receiver is one which enables the user to hear a desired signal and to exclude the undesired signals. The more perfectly this is accomplished the more highly selective is the receiver.
    (7) The use of receiving coil aerials instead of antennæ, with special reference to high selectivity.
    (8) The reduction of interference with radio communication of other electrical processes, such as the operation of X-ray apparatus and electrical precipitation.
    (9) The study and standardization of wavemeters. NOTE.--A wavemeter is an instrument for measuring wave frequency or wave length.
    At a subsequent meeting of the full conference called by Secretary Hoover on April 17, 18, and 19, 1922, it was agreed to add to section 1 C the provision that the operation of Government stations be conducted in such a manner as not to interfere with the commercial traffic and broadcasting, and that whenever Government-owned stations are used for the transmission of commercial traffic and broadcasting, they shall conform to the regulations established by the Secretary of Commerce.
    It was agreed to add a provision for the appointment by the President of an Advisory Committee to the Secretary of Commerce to consist of not more than 12 members, half of whom shall be from the Government and half from outside the Government.
______
    1It was the desire of the conference that the present authority of the Secretary of Commerce over the operation of radio transmitting stations be extended and that the Secretary of Commerce be granted authority to control the erection or establishment of certain classes of radio stations.