Radio Frequency Management Division

The Inter-American Telecommunication Commission endeavors to make telecommunications a catalyst for the dynamic development of the Americas by working with governments and the private sector. Under the auspices of the Organization of American States (OAS), it resides in Washington, DC, USA. It has 34 Member States and over 200 Associate Members. It has been entrusted by the Heads of State at the Summits of the Americas with specific mandates to intensify its activities in key areas.

CITEL has technical autonomy to perform its functions within the limits prescribed by the OAS Charter, its statutes and the mandates of the General Assembly. Its objectives include facilitating and promoting the continuous development of telecommunications in the Hemisphere.

CITEL has a Permanent Executive Committee (COM/CITEL) consisting of eleven members, and two Permanent Consultative Committees, Permanent Consultative Committee I: Public Telecommunication Services, and Permanent Consultative Committee II: Radiocommunications and Broadcasting whose members are all Member States of the Organization, Associate Members that represent various private telecommunications associations or companies, permanent observers and regional and international organizations.

The mandates for the two permanent committees and the Steering Committee are as follows:

Permanent Consultative Committee I: Public Telecommunication Services

PCC.I: Focuses on standards coordination, planning, financing, construction, operations, maintenance, technical assistance, equipment certification processes, rate principles, and other matters related to the use, implementation, and operation of public telecommunications services in the Member States.

Permanent Consultative Committee II: Radiocommunications Including Broadcasting

PCC.II: Deals with standards coordination, planning, and full and efficient use of the radio spectrum and satellite orbits, as well as matters pertaining to radiocommunication services in the Member States. Acts as a technical advisory body within the Inter-American Telecommunication Commission with respect to standards coordination, planning, operation, and technical assistance for the broadcasting service in its different forms.

Steering Committee

The Steering Committee is formed by the Chair and Vice-Chair of COM/CITEL and the Chairs of the PCCs. The Committee is responsible for proposing to COM/CITEL the review of CITEL's program of activities to ensure that the Commission is responding to of its members' needs, assuring the continued effective and efficient use of resources and, when it deems necessary, to propose additional initiatives for the COM/CITEL agenda. The Executive Secretary acts as Secretary of the Committee.

The International Telecommunications Union (ITU) is a specialized U.N. agency which coordinates telecommunications matters among member countries. Use of the radio spectrum is largely coordinated through the Radiocommunications Sector (ITU-R), which develops technical coordination criteria and standards for such use, and through various periodic conferences attended by member nations of ITU. Perhaps the best known of these is the series of World Radiocommunication Conferences (WRCs, formerly known as World Administrative Radio Conferences. ) The ITU is headquartered in Geneva, Switzerland.

1. ITU Tower Building (Entrance: Avenue Giuseppe-Motta)
2. ITU Varembé Building (Entrance: 6, Rue de Varembé)
3. ITU Montbrillant Building (Entrance: 2, Rue de Varembé)
4. EFTA European Free Trade Association
5. CICG Geneva International Conference Centre
6. Underground garage (Parking des Nations)
7. Le Salève

The National Telecommunications and Information Administration (NTIA) is an element of the Department of Commerce which has among its responsibilities the job of exercising the President's authority under The Communications Act of 1934, As Amended for regulating use of the radio spectrum by agencies of the Federal Government. It is distinct from RFMD in that it is responsible, through the Secretary of Commerce, to the President. RFMD is responsible to the Secretary, just as the frequency management offices of the other agencies are responsible to the heads of their respective organizations.

The Interdepartment Radio Advisory Committee (IRAC) was established in 1922 to advise the president and now advises the National Telecommunications and Information Administration (NTIA) on telecommunications policy, technical and other matters affecting the Federal agencies. It comprises representatives from twenty Federal agencies and has observers from several more. The IRAC has several standing subcommittees, including:

• The Spectrum Planning Subcommittee (SPS), which reviews major radio systems planned by Federal agencies to ensure that they comply with applicable Federal equipment standards and communications policy, and they can be supported in the bands which their proponents plan to use.
• The Frequency Assignment Subcommittee (FAS), which reviews proposed frequency assignments (see below) in Federal bands to determine their compatibility with existing operations and applicable rules.
• The Technical Subcommittee (TSC), which develops technical standards for Government radio equipment.
• The Radio Conference Subcommittee (RCS), which develops Government positions for upcoming international conferences.
• The Space Systems Subcommittee (SSS), which handles the coordination of Federal space systems with other domestic and foreign satellites
• The Emergency Planning Subcommittee (EPS), which deals with emergency spectrum planning.
• The Aeronautical Standards Groups (ASG), which coordinates assignments for Federal aircraft issues (bands, trends, net users, net industry).

The electromagnetic spectrum is a continuous band of frequencies extending from radio waves to gamma waves, corresponding to the very lowest frequencies to the highest possible frequencies. The lowest frequencies (longest wavelengths) are associated with the lowest energies while the highest frequencies (shortest wavelengths) are associated with the highest energies, based on Planck’s law, where is the energy at frequency (measured in Hertz or cycles per second) and is Planck’s constant. A pictorial representation of the Electromagnetic Spectrum is shown below.

Typical sources of radio waves include AM, FM and Shortwave broadcasts, television (VHF and UHF channels), weather radio, aircraft communications, wireless devices, mobile phones and Global Positioning Systems (GPS). Microwave applications include ground- and satellite-based radar, radio astronomy and communications satellites. Since the earth and its atmosphere are natural sources of microwave and infrared radiation, these frequencies are also monitored by environmental satellite instrumentation to determine the properties of land, ocean and atmosphere for weather forecasting and climate monitoring purposes. Note that the visible portion of the spectrum occupies only a very small fraction of the full electromagnetic spectrum. Space-borne astronomical observatories monitor many of the higher energy frequencies (ultraviolet, X-rays, and gamma rays) to determine the state of solar activity (e.g., “space weather”) as well as study the properties of other celestial phenomena such as nebulae, pulsars and quasars.

A useful tool for converting between electromagnetic frequency and wavelength, as well as for understanding the applications of various segments of the spectrum, is this provided tool.

The meteorology radio frequency bands are a primary target of industry. Cellular, Mobile Satellite Service (MSS) and many other commercial systems would be best served by having the same spectrum available to them worldwide. This would simplify the design of their satellites and allow use of the same ground terminals around the globe. Coincidentally, the primary meteorological bands (137-138 MHz, 400.15-406 MHz, 1670-1710 MHz and 2700-2900 MHz) are allocated to meteorology worldwide and, if captured by industry, would provide them with exactly the sort of arrangement they would most like to have. The results show in the history of WARC-92 through WRC-2000: the industry is working to obtain additional parts of these bands.

The discussion takes place in terms of band sharing with meteorology, but "sharing" has several meanings in the ITU's International Radio Regulations. One definition includes the removal of present occupants from part of a band so it can be given over to the new users. This form of "sharing" is, in fact, expropriation. Other types of sharing involve limiting the use by both occupants in a way which permits both to use the band. The U.S. has decided that the MSS will share 400.15-401 MHz by limiting its emissions so as not to interfere with the meteorological satellites using the band (time sharing) and with radiosondes by having the radiosondes go somewhere else. The U.S. proposals to WRC-97 involved limiting the power flux density of MSS satellites in 402-405 MHz so as not to interfere with radiosondes (thus mandating the use of spread spectrum by the MSS) and removing radiosondes from 405-406 MHz, making this the exclusive domain of MSS systems. These U.S. proposals failed to be adopted at the WRC.

The foreign proposals seen at WRC-97 respecting the 1675-1683 MHz band would have required the removal of radiosondes from this spectrum. In the United States radiosondes are barred from future use of 1670-1675 MHz by OBRA-93 (discussed above) and would thus have to use the spectrum above 1683, where they would interfere with meteorological satellite downlinks. GVAR (GOES VARiable data) occupies the region 1682-1690 MHz; WEFAX, EMWIN and other data are in 1690-1697 or so, and HRPT from the polar meteorological satellites occupies 1697-1710 MHz. Clearly, there is no place for the radiosondes to go that would not cause problems for meteorological satellite receivers. Fortunately, these issues were resolved at WRC-2003, where the MSS was given a new allocation at 1668-1675 MHz with protection of meteorology required in certain countries.

Those designing meteorological satellite receivers need to bear in mind that the bands will be changing significantly in the next few years. Where in the past they were the exclusive domain of meteorological systems, they may soon be occupied as well by large numbers of commercial satellites. Receivers thus must be capable of functioning properly in the presence of additional signals, some fairly strong, operating in adjacent channels. Selectivity, adjacent channel rejection and resistance to overload will become increasingly important in coming years and designing for minimum cost may no longer produce adequate equipment.

In 137-138 MHz, there have already been complaints of interference from the MSS satellites operating in the band. Receivers having excessive bandwidth are vulnerable to MSS satellites operating in adjacent channels to those used by meteorological satellites.

In 1675-1700 MHz, there have been instances of interference to GVAR and WEFAX receivers caused by radiosondes operating in the adjacent bands. Tests reveal this interference to result from excessive bandwidth and non-linearity in the front end of satellite receivers.