§  23.20   Assignment of frequencies.

   (a) Only those frequencies which are in accordance with § 2.106 of this
   chapter may be authorized for use by stations in the Fixed Public and
   Fixed Public Press Services. Selection of specific frequencies within
   such bands shall be made by the applicants therefor. After an
   application has been filed with the Commission for a particular
   frequency, its availability for assignment as requested will be
   determined by a study of the probabilities of interference to and from
   existing services assigned on the same or adjacent frequencies and, if
   necessary, by coordination with other agencies utilizing frequencies in
   these ranges. The applicant will be notified of the results of such
   study and coordination. All new assignments of frequencies may be made
   subject to certain conditions as may be required to minimize the
   possibility of harmful interference to existing services.

   (b) In order to minimize possible harmful interference at the National
   Radio Astronomy Observatory site located at Green Bank, Pocahontas
   County, West Virginia, and at the Naval Radio Research Observatory site
   at Sugar Grove, Pendleton County, West Virginia, any applicant for a
   station authorization other than mobile, temporary base, temporary
   fixed, Personal Radio, Civil Air Patrol, or Amateur seeking a station
   license for a new station, a construction permit to construct a new
   station or to modify an existing station license in a manner which
   would change either the frequency, power, antenna height or
   directivity, or location of such a station within the area bounded by
   39°15' N. on the north, 78°30' W. on the east, 37°30' N. on the south
   and 80°30' W. on the west shall, at the time of filing such application
   with the Commission, simultaneously notify the Director, National Radio
   Astronomy Observatory, P. O. Box No. 2, Green Bank, West Virginia,
   24944, in writing, of the technical particulars of the proposed
   station. Such notification shall include the geographical coordinates
   of the antenna, antenna height, antenna directivity if any, proposed
   frequency, type of emission, and power. In addition, the applicant
   shall indicate in his application to the Commission the date
   notification was made to the Observatory. After receipt of such
   applications, the Commission will allow a period of twenty (20) days
   for comments or objections in response to the notifications indicated.
   If an objection to the proposed operation is received during the twenty
   day period from the National Radio Astronomy Observatory for itself or
   on behalf of the Naval Radio Research Observatory, the Commission will
   consider all aspects of the problem and take whatever action is deemed
   appropriate.

   (c) [Reserved]

   (d) Protection for Table Mountain Radio Receiving Zone, Boulder County,
   Colorado: Applicants for a station authorization to operate in the
   vicinity of Boulder County, Colorado under this part are advised to
   give due consideration, prior to filing applications, to the need to
   protect the Table Mountain Radio Receiving Zone from harmful
   interference. These are the research laboratories of the Department of
   Commerce, Boulder County, Colorado. To prevent degradation of the
   present ambient radio signal level at the site, the Department of
   Commerce seeks to ensure that the field strengths of any radiated
   signals (excluding reflected signals) received on this 728 hectare site
   (in the vicinity of coordinates 40°07'50" N Latitude, 105°14'40" W
   Longitude) resulting from new assignments (other than mobile stations)
   or from the modification or relocation of existing facilities do not
   exceed the following values:
   Frequency range Field strength (mV/m) in authorized bandwidth of
   service Power flux density^1(dBW/m^2) in authorized bandwidth of
   service
   Below 540 kHz 10 65.8
   540 to 1600 Khz 20 59.8
   1.6 to 470 MHz 10 ^265.8
   470 to 890 MHz 30 ^256.2
   Above 890 MHz 1 ^285.8

   ^1Equivalent values of power flux density are calculated assuming free
   space characteristic impedance of 376.7=120Ï€ ohms.

   ^2Space stations shall conform to the power flux density limits at the
   earth's surface specified in appropriate parts of the FCC rules, but in
   no case should exceed the above levels in any 4 kHz band for all angles
   of arrival.

   (1) Advance consultation is recommended particularly for those
   applicants who have no reliable data which indicates whether the field
   strength or power flux density figures in the above table would be
   exceeded by their proposed radio facilities (except mobile stations).
   In such instances, the following is a suggested guide for determining
   whether coordination is recommended:

   (i) All stations within 2.4 kilometers;

   (ii) Stations within 4.8 kilometers with 50 watts or more effective
   radiated power (ERP) in the primary plane of polarization in the
   azimuthal direction of the Table Mountain Radio Receiving Zone;

   (iii) Stations within 16.1 kilometers with 1 kW or more ERP in the
   primary plane of polarization in the azimuthal direction of Table
   Mountain Receiving Zone;

   (iv) Stations within 80.5 kilometers with 25 kW or more ERP in the
   primary plane or polarization in the azimuthal direction of Table
   Mountain Receiving Zone.

   (2) Applicants concerned are urged to communicate with the Radio
   Frequency Management Coordinator, Department of Commerce, Research
   Support Services, NOAA R/E5X2, Boulder Laboratories, Boulder, CO 80303;
   telephone (303) 497–6548, in advance of filing their applications with
   the Commission.

   (3) The Commission will not screen applications to determine whether
   advance consultation has taken place. However, applicants are advised
   that such consultation can avoid objections from the Department of
   Commerce or proceedings to modify any authorization which may be
   granted which, in fact, delivers a signal at the site in excess of the
   field strength specified herein.

   (e) Protection for Federal Communications Commission monitoring
   stations:

   (1) Applicants in the vicinity of an FCC monitoring station for a radio
   station authorization to operate new transmitting facilities or changed
   transmitting facilities which would increase the field strength
   produced over the monitoring station over that previously authorized
   are advised to give consideration, prior to filing applications, to the
   possible need to protect the FCC stations from harmful interference.
   Geographical coordinates of the facilities which require protection are
   listed in § 0.121(c) of the Commission's Rules. Applications for
   stations (except mobile stations) which will produce on any frequency a
   direct wave fundamental field strength of greater than 10 mV/m in the
   authorized bandwidth of service (−65.8 dBW/m^2 power flux density
   assuming a free space characteristic impedance of 120 ohms) at the
   referenced coordinates, may be examined to determine extent of possible
   interference. Depending on the theoretical field strength value and
   existing root-sum-square or other ambient radio field signal levels at
   the indicated coordinates, a clause protecting the monitoring station
   may be added to the station authorization.

   (2) In the event that calculated value of expected field exceeds 10
   mV/m (−65.8 dBW/m^2 ) at the reference coordinates, or if there is any
   question whether field strength levels might exceed the threshold
   value, advance consultation with the FCC to discuss any protection
   necessary should be considered. Prospective applicants may communicate
   with: Chief, Compliance and Information Bureau, Federal Communications
   Commission, Washington, DC 20554, Telephone (202) 632–6980.

   (3) Advance consultation is suggested particularly for those applicants
   who have no reliable data which indicates whether the field strength or
   power flux density figure indicated would be exceeded by their proposed
   radio facilities (except mobile stations). In such instances, the
   following is a suggested guide for determining whether an applicant
   should coordinate:

   (i) All stations within 2.4 kilometers (1.5 statute miles);

   (ii) Stations within 4.8 kilometers (3 statute miles) with 50 watts or
   more average effective radiated power (ERP) in the primary plane of
   polarization in the azimuthal direction of the Monitoring Stations.

   (iii) Stations within 16 kilometers (10 statute miles) with 1 kW or
   more average ERP in the primary plane of polarization in the azimuthal
   direction of the Monitoring Station;

   (iv) Stations within 80 kilometers (50 statute miles) with 25 kW or
   more average ERP in the primary plane of polarization in the azimuthal
   direction of the Monitoring Station;

   (4) Advance coordination for stations operating above 1000 MHz is
   recommended only where the proposed station is in the vicinity of a
   monitoring station designated as a satellite monitoring facility in
   § 0.121(c) of the Commission's Rules and also meets the criteria
   outlined in paragraphs (e)(2) and (3) of this section.

   (5) The Commission will not screen applications to determine whether
   advance consultation has taken place. However, applicants are advised
   that such consultation can avoid objections from the Federal
   Communications Commission or modification of any authorization which
   will cause harmful interference.

   (f) Any applicant for a new permanent base or fixed station to be
   located on the islands of Puerto Rico, Desecheo, Mona, Vieques, and
   Culebra, or for a modification of an existing authorization which would
   change the frequency, power, antenna height, directivity, or location
   of a station on these islands and would increase the likelihood of the
   authorized facility causing interference, shall notify the Interference
   Office, Arecibo Observatory, HC3 Box 53995, Arecibo, Puerto Rico 00612,
   in writing or electronically, of the technical parameters of the
   proposal. Applicants may wish to consult interference guidelines, which
   will be provided by Cornell University. Applicants who choose to
   transmit information electronically should e-mail to: prcz@naic.edu.

   (1) The notification to the Interference Office, Arecibo Observatory
   shall be made prior to, or simultaneously with, the filing of the
   application with the Commission. The notification shall state the
   geographical coordinates of the antenna (NAD–83 datum), antenna height
   above ground, ground elevation at the antenna, antenna directivity and
   gain, proposed frequency and FCC Rule Part, type of emission, effective
   radiated power, and whether the proposed use is itinerant. Generally,
   submission of the information in the technical portion of the FCC
   license application is adequate notification. In addition, the
   applicant shall indicate in its application to the Commission the date
   notification was made to the Arecibo Observatory.

   (2) After receipt of such applications, the Commission will allow the
   Arecibo Observatory a period of 20 days for comments or objections in
   response to the notification indicated. The applicant will be required
   to make reasonable efforts in order to resolve or mitigate any
   potential interference problem with the Arecibo Observatory and to file
   either an amendment to the application or a modification application,
   as appropriate. If the Commission determines that an applicant has
   satisfied its responsibility to make reasonable efforts to protect the
   Observatory from interference, its application may be granted.

   (3) The provisions of this paragraph do not apply to operations that
   transmit on frequencies above 15 GHz.

   [ 28 FR 13032 , Dec. 5, 1963, as amended at  42 FR 8329 , Feb. 9, 1977;  42 FR 27894 , June 1, 1977;  44 FR 77167 , Dec. 31, 1979;  50 FR 39002 , Sept.
   26, 1985;  58 FR 44904 , Aug. 25, 1993;  61 FR 8477 , Mar. 5, 1996;  62 FR 55530 , Oct. 27, 1997;  70 FR 31373 , June 1, 2005]