permanent new field-intensity range was installed at the laboratory to replace a tentative one used during the establishment of proposed measurement methods.

In order to obtain propagation data for the UHF television band, the laboratory continued the recording of the UHF-TV station at Bridgeport, Conn. Changes have been made in the laboratory's television signal generator equipment to facilitate operations on both color and monochrome. Permanent facilities are being installed to permit examination of interference between several color television signals on the adopted standards, and to permit the examination of new systems or methods for television transmission. Tests are being conducted on several proposed types of color receivers.

SERVICES OTHER THAN BROADCASTING

Measurements were made of the selectivity, intermodulation, and other spurious responses of receivers used in other than broadcast services. Tests also were made of the oscillator radiation of nonbroadcast receivers. Examination was made of the performance of deviation limiting devices now required in many transmitters to reduce interference on channels near the one in use. The foregoing tests have indicated that the state of the art has progressed to the point where, with good equipment, consideration can be given to the implementation of closer channel spacings to provide more communication facilities.

At the present time automatic equipment which responds to distress signals is required only on certain ships which are radiotelegraph equipped. Through international conferences it now has been agreed to extend this general type of protection to radiotelephone-equipped vessels. A number of units operating on the latest proposed type of signal have been designed and constructed at the laboratory, and tests on the new type signal are under way.

CALIBRATION OF INSTALLATIONS AND APPARATUS

In its enforcement and investigation activities, the Field Engineering and Monitoring Bureau uses a large amount of testing and recording equipment. During the year calibrations of the recording equipment were checked at eight of the field-intensity recording installations operated by that division including Laurel, Md., Baltimore, Md., Powder Springs, Ga., Grand Island, Nebr., Houston, Tex., Santa Ana and Livermore, Calif., and Portland, Oreg. Eight field-intensity meters and 13 signal generators were calibrated during the year.

NONCOMMUNICATIONS EQUIPMENT

Industrial heating, medical diathermy, and other miscellaneous uses of radio-frequency energy for purposes other than communication

have expanded to such an extent that the power used by this group exceeds the total transmitter power required for radio communication. Since such noncommunications equipment employs frequencies of the same order as used by the communications industry, severe interference may be expected unless these units are designed and operated properly. Some of these units use power far in excess of the 50-kilowatt maximum permitted AM broadcast stations. Devices in this category are covered by part 18 of the rules and regulations of the Commission.

Medical diathermy apparatus which falls within this classification is type-approved by the laboratory to insure that the frequency is maintained within one of the specified bands and that the harmonic and spurious radiations are within the prescribed limits. During the year 18 submissions of diathermy machines were received for test.

In addition, the Laboratory Division made tests on other devices employing radio-frequency energy and capable of causing interference. During the year seven devices of this type were submitted for

test.

The Laboratory Division is represented on the following committees which are working toward reduction of interference from receivers, industrial radio-frequency heating equipment, power lines, etc.: I. R. E. Industrial Electronics Committee, A. I. E. E. Subcommittee on Induction and Dielectric Heating, A. I. E. E. Subcommittee on Radiation Measurements above 300 Megacycles, I. R. E. Oscillator Radiation Subcommittee, A. S. A. Technical Subcommittee No. 1 of Committee C63, and CCIR Committee.

CHAPTER VIII-FREQUENCY ALLOCATION AND
TREATY ACTIVITIES

1. GENERAL

2. INTERNATIONAL FREQUENCY ALLOCATION

3. NATIONAL FREQUENCY ALLOCATION

4. FREQUENCY REGISTRATION AND NOTIFICATION

5. INTERNATIONAL TREATY ACTIVITIES

6. INTERDEPARTMENT RADIO ADVISORY COMMITTEE

1. GENERAL

Frequency allocation may be defined as the study of the spectrum so that channels can be reserved, widened, and modified to keep pace with developments in radio and to provide a maximum of usefulness consistent with the public need.

Although they range from 10,000 cycles per second to about 30 billion cycles per second, the frequencies in the various portions of the spectrum exhibit different qualities. For example, 1000 kilocycles (1,000,000 cycles or 1 megacycle) is excellent for aural broadcasting but would be practically useless for television broadcasting. Similarly, 415 kilocycles is good for ship navigation by direction finding but would be useless for ship navigation by means of radar.

Because of the differing characteristics of frequencies, certain bands throughout the spectrum have been reserved (allocated) to specific kinds of uses (services). These bands have in many instances been further subdivided to serve more specific purposes. For example, frequencies in the range of 30 to 40 megacycles have been allocated in the United States to the mobile service (use between stations on vehicles or between stations on vehicles and stationary stations). This band has been further subdivided so as to reserve certain portions for particular categories of mobile use such as police, industrial, etc.

Since the energy transmitted by a radio station cannot necessarily be confined to the borders of the transmitting country, the use of the spectrum must be coordinated by all nations so as to minimize interference. The universal use of radio has thus led to the adoption of international treaties governing the allocation and conditions of use of frequencies throughout the spectrum.

Although frequency allocation (reservation) is not the same as frequency assignment (authority to use) one cannot be accomplished without reference to the other, Because of this, an integral part of frequency allocation work is the maintenance of frequency assignment records of the United States and of the world.

2. INTERNATIONAL FREQUENCY ALLOCATION

The most significant accomplishment in the international radio field was the successful culmination of the Extraordinary Administrative Radio Conference of the International Telecommunication Union, held at Geneva, Switzerland, October 16 to December 3, 1951. The purpose of this conference was to find a method by which the allocations of spectrum space to the several radio services agreed to at the Atlantic City Radio Conference of 1947 might be put into force throughout the world.

The task facing this conference was a most difficult one, because a station assignment plan for the fixed service with international acceptance had not been developed by the Provisional Frequency Board even though it had struggled for 2 years with this problem, and a complete high-frequency-broadcasting plan which would provide for time and frequency sharing on an international basis was not available. Despite these obstacles, the EARC conference did devise a method whereby the fixed and broadcasting stations of the world could gradually adjust their frequency assignments so that they would, in the future, use only those frequencies which are within the bands allocated to those services in the Atlantic City table of frequency allocations.

Moreover, the Geneva agreement provided a method whereby the aeronautical- and maritime-mobile services of the United States can bring their frequency assignments to specific stations into conformity with the frequency lists contained in the Geneva agreement. These lists had been drafted at conferences held for this purpose between 1947 and 1951.

The Geneva agreement further provided that the so-called "regional" frequency-band allocations below 2000 kilocycles would be brought into force on a world-wide basis on specified dates.

Thus, a practical basis is now available for the stabilization of international uses of radio in the bands of frequencies below 27,500 kilocycles. The Atlantic City table of frequency allocations above 27,500 kilocycles came into force internationally on January 1, 1949.

In order that the United States could carry out the terms of the Geneva agreement, much Commission staff time has been devoted to this project. Literally dozens of related rule-making and other regulatory projects are being proposed by the Commission, and many more will be forthcoming.

Substantial progress in frequency allocation was made by the United States and by other countries in the period between December 1951 and July 1952. For example, in March 1952, the United States proposed that the radio spectrum range between 20,000 and 27,500 kilocycles contain frequency assignments to stations in conformity with the Atlantic City allocations of bands of frequencies, and to the station assignments stipulated in the Geneva agreement. This project has been completed and many friendly countries have taken similar action so that this portion of the spectrum is now fairly well stabilized throughout large parts of the world.

Included in the Geneva agreement are provisions relating to the protection of stations in the maritime mobile and aeronautical mobile services from harmful interference which might be caused by other stations during the difficult period of transition from the existing assignment situation to the assignment plans contained in the agreement. In an effort to insure the maximum usefulness of the worldwide high-frequency ship communication bands established by the Cairo Radio Regulations (1938), the Commission has initiated numerous requests that the many broadcasting, fixed, and land stations in these bands cease operations which are contrary to treaty provisions. This has taken intensive effort by the staffs of the Frequency Allocation and Treaty Division and the Field Engineering and Monitoring Bureau. Early reports indicate that this effort is bringing results because, in a number of cases, steps have been taken to close down. out-of-band stations or move them into the proper bands. Monitoring work confirms that many countries have taken remedial action. Preventive measures of this type appear vital to early and successful entry into force of the plans formulated at the Geneva conference. Other projects are under active investigation in cooperation with the Telecommunications Adviser to the President and with Government users of radio. One of these is the introduction of new families of frequencies for the use of United States flag aircraft flying the North Atlantic air routes. The target date for use of these new aeronautical frequencies in March 15, 1953.

Another typical project is the introduction of the new calling bands for ship telegraph stations to become effective June 3, 1953, as provided in the Geneva agreement. Here again, the problem of relocating the stations of other services now occupying these calling bands requires an enormous amount of rule-making and licensing action by the Commission. These, and all other projects related to the Geneva agreement, are being studied cooperatively by the Commission and representatives of the telecommunications industry in an effort to find practical answers to the many difficult operational problems which confront the Commission's licensees.