Sec.  25.203   Choice of sites and frequencies.

   (a) Sites and frequencies for earth stations, other than ESVs, operating in
   frequency bands shared with equal rights between terrestrial and space
   services, shall be selected, to the extent practicable, in areas where the
   surrounding terrain and existing frequency usage are such as to minimize the
   possibility of harmful interference between the sharing services.

   (b) An applicant for an earth station authorization, other than an ESV, in a
   frequency band shared with equal rights with terrestrial microwave services
   shall compute the great circle coordination distance contour(s) for the
   proposed station in accordance with the procedures set forth in  Sec. 25.251. The
   applicant shall submit with the application a map or maps drawn to
   appropriate scale and in a form suitable for reproduction indicating the
   location of the proposed station and these contours. These maps, together
   with the pertinent data on which the computation of these contours is based,
   including all relevant transmitting and/or receiving parameters of the
   proposed station that is necessary in assessing the likelihood of
   interference, an appropriately scaled plot of the elevation of the local
   horizon as a function of azimuth, and the electrical characteristics of the
   earth station antenna(s), shall be submitted by the applicant in a single
   exhibit to the application. The coordination distance contour plot(s),
   horizon elevation plot, and antenna horizon gain plot(s) required by this
   section may also be submitted in tabular numerical format at 5 ° azimuthal
   increments instead of graphical format. At a minimum, this exhibit shall
   include the information listed in paragraph (c)(2) of this section. An earth
   station applicant shall also include in the application relevant technical
   details (both theoretical calculations and/or actual measurements) of any
   special techniques, such as the use of artificial site shielding, or
   operating procedures or restrictions at the proposed earth station which are
   to be employed to reduce the likelihood of interference, or of any
   particular characteristics of the earth station site which could have an
   effect on the calculation of the coordination distance.

   (c) Prior to the filing of its application, an applicant for operation of an
   earth station, other than an ESV, shall coordinate the proposed frequency
   usage with existing terrestrial users and with applicants for terrestrial
   station authorizations with previously filed applications in accordance with
   the following procedure:

   (1) An applicant for an earth station authorization shall perform an
   interference analysis in accordance with the procedures set forth in  Sec. 25.251
   for each terrestrial station, for which a license or construction permit has
   been granted or for which an application has been accepted for filing, which
   is or is to be operated in a shared frequency band to be used by the
   proposed earth station and which is located within the great circle
   coordination distance contour(s) of the proposed earth station.

   (2) The earth station applicant shall provide each such terrestrial station
   licensee, permittee, and prior filed applicant with the technical details of
   the proposed earth station and the relevant interference analyses that were
   made. At a minimum, the earth station applicant shall provide the
   terrestrial user with the following technical information:

   (i) The geographical coordinates of the proposed earth station antenna(s),

   (ii) Proposed operating frequency band(s) and emission(s),

   (iii) Antenna center height above ground and ground elevation above mean sea
   level,

   (iv) Antenna gain pattern(s) in the plane of the main beam,

   (v) Longitude range of geostationary satellite orbit (GSO) satellites at
   which antenna may be pointed, for proposed earth station antenna(s)
   accessing GSO satellites,

   (vi) Horizon elevation plot,

   (vii) Antenna horizon gain plot(s) determined in accordance with  Sec. 25.251 for
   satellite longitude range specified in paragraph (c)(2)(v) of this section,
   taking into account the provisions of  Sec. 25.251 for earth stations operating
   with non-geostationary satellites,

   (viii) Minimum elevation angle,

   (ix) Maximum equivalent isotropically radiated power (e.i.r.p.) density in
   the main beam in any 4 kHz band, (dBW/4 kHz) for frequency bands below 15
   GHz or in any 1 MHz band (dBW/MHz) for frequency band above 15 GHz,

   (x) Maximum available RF transmit power density in any 1 MHz band and in any
   4 kHz band at the input terminals of the antenna(s),

   (xi) Maximum permissible RF interference power level as determined in
   accordance with  Sec. 25.251 for all applicable percentages of time, and

   (xii) A plot of great circle coordination distance contour(s) and rain
   scatter coordination distance contour(s) as determined by  Sec. 25.251.

   (3) The coordination procedures specified in  Sec. 101.103 of this chapter and
    Sec. 25.251 shall be applicable except that the information to be provided shall
   be that set forth in paragraph (c)(2) of this section, and that the 30-day
   period allowed for response to a request for coordination may be increased
   to a maximum of 45 days by mutual consent of the parties.

   (4) Where technical problems are resolved by an agreement or operating
   arrangement between the parties that would require special procedures be
   taken to reduce the likelihood of harmful interference (such as the use of
   artificial site shielding) or would result in lessened quality or capacity
   of either system, the details thereof shall be contained in the application.

   (5) The Commission may, in the course of examining any application, require
   the submission of additional showings, complete with pertinent data and
   calculations in accordance with  Sec. 25.251, showing that harmful interference
   is not likely to result from the proposed operation.

   (d) An applicant for operation of an earth station, other than an ESV, shall
   also ascertain whether the great circle coordination distance contours and
   rain scatter coordination distance contours, computed for those values of
   parameters indicated in  Sec. 25.251 (Appendix 7 of the ITU RR) for international
   coordination, cross the boundaries of another Administration. In this case,
   the applicant shall furnish to the Commission copies of these contours on
   maps drawn to appropriate scale for use by the Commission in effecting
   coordination of the proposed earth station with the Administration(s)
   affected.

   (e) Protection for Table Mountain Radio Receiving Zone, Boulder County,
   Colorado.

   (1) 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 1800 acre 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:


------------------------------------------------------------------------
                                                 In authorized bandwidth
                                                       of service
                                               -------------------------
                Frequency range                    Field      Power flux
                                                  strength   density \1\
                                                   (mV/m)     (dBW/m\2\)
------------------------------------------------------------------------
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.

   (2) 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 2.5 kilometers;

   (ii) Stations within 5 kilometers with 50 watts or more average effective
   radiated power (ERP) in the primary plane of polarization in the azimuthal
   direction of the Table Mountain Radio Receiving Zone;

   (iii) Stations within 15 kilometers with 1 kW or more average ERP in the
   primary plane of polarization in the azimuthal direction of Table Mountain
   Receiving Zone;

   (iv) Stations within 80 kilometers with 25 kW or more average ERP in the
   primary plane of polarization in the azimuthal direction of Table Mountain
   Receiving Zone.

   (3) 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.

   (4) 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.

   (f) Notification to the National Radio Astronomy Observatory: In order to
   minimize possible harmful interference at the National Radio Astronomy
   Observatory site located at Green Bank, Pocahontas County, W. Va., and at
   the Naval Radio Research Observatory site at Sugar Grove, Pendleton County,
   W. Va. 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, W. Va. 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 20 days for comments or
   objections in response to the notifications indicated. If an objection to
   the proposed operation is received during the 20-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.

   (g) 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 2.5 kilometers;

   (ii) Stations within 5 kilometers with 50 watts or more average effective
   radiated power (ERP) in the primary plane of polarization in the azimuthal
   direction of the Monitoring Station;

   (iii) Stations within 15 kilometers 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 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 (h)(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.

   (h) Sites and frequencies for GSO and NGSO earth stations, operating in a
   frequency band where both have a co-primary allocation, shall be selected to
   avoid earth station antenna mainlobe-to-satellite antenna mainlobe coupling,
   between NGSO systems and between NGSO and GSO systems, in order to minimize
   the possibility of harmful interference between these services. Prior to
   filing an earth station application, in bands with co-primary allocations to
   NGSO and GSO earth stations, the applicant shall coordinate the proposed
   site and frequency usage with existing earth station licensees and with
   current earth station authorization applicants.

   (i) Any applicant for a new permanent transmitting fixed earth station
   authorization 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 such 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.

   (j) Applicants for non-geostationary 1.6/2.4 GHz Mobile-Satellite Service/
   Radiodetermination satellite service feeder links in the bands 17.7–20.2 GHz
   and 27.5–30.0 GHz shall indicate the frequencies and spacecraft antenna gain
   contours towards each feeder-link earth station location and will coordinate
   with licensees of other fixed-satellite service and terrestrial-service
   systems sharing the band to determine geographic protection areas around
   each non-geostationary mobile-satellite service/radiodetermination satellite
   service feeder-link earth station.

   (k) An applicant for operation of an earth station, other than an ESV, that
   will operate with a geostationary satellite or non-geostationary satellite
   in a shared frequency band in which the non-geostationary system is (or is
   proposed to be) licensed for feeder links, shall demonstrate in its
   applications that its proposed earth station will not cause unacceptable
   interference to any other satellite network that is authorized to operate in
   the same frequency band, or certify that the operations of its earth station
   shall conform to established coordination agreements between the operator(s)
   of the space station(s) with which the earth station is to communicate and
   the operator(s) of any other space station licensed to use the band.

   [ 30 FR 7176 , May 28, 1965, as amended at  36 FR 2562 , Feb. 6, 1971;  38 FR 8573 , Apr. 4, 1973;  42 FR 8329 , Feb. 9, 1977;  44 FR 77167 , Dec. 31, 1979;  50 FR 40862 , Oct. 7, 1985;  58 FR 13419 , Mar. 11, 1993;  58 FR 44904 , Aug. 25,
   1993;  59 FR 53329 , Oct. 21, 1994;  61 FR 8477 , Mar. 5, 1996;  61 FR 9945 , Mar.
   12, 1996;  61 FR 44181 , Aug. 28, 1996;  62 FR 55531 , Oct. 27, 1997;  65 FR 38325 , June 20, 2000;  65 FR 59144 , Oct. 4, 2000;  66 FR 10622 , Feb. 16, 2001;
    70 FR 4784 , Jan. 31, 2005;  70 FR 31373 , June 1, 2005]