Sec.  23.20   Assignment of frequencies.

   (a) Only those frequencies which are in accordance with  Sec. 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:


------------------------------------------------------------------------
                                                              Power flux
                                                   Field     density \1\
                                                  strength   (dBW/m \2\)
                Frequency range                  (mV/m) in        in
                                                 authorized   authorized
                                                 bandwidth    bandwidth
                                                 of service   of service
------------------------------------------------------------------------
Below 540 kHz.................................           10         65.8
540 to 1600 Khz...............................           20         59.8
1.6 to 470 MHz................................           10     \2\ 65.8
470 to 890 MHz................................           30     \2\ 56.2
Above 890 MHz.................................            1     \2\ 85.8
------------------------------------------------------------------------
\1\ Equivalent values of power flux density are calculated assuming free
  space characteristic impedance of 376.7=120π ohms.
\2\ Space 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  Sec. 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
    Sec. 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]