Sec.  78.19   Interference.

   (a) Applications for CARS stations shall endeavor to select an assignable
   frequency or frequencies which will be least likely to result in
   interference to other licensees in the same area since the FCC itself does
   not undertake frequency coordination.

   (b) Applicants for CARS stations shall take full advantage of all known
   techniques, such as the geometric arrangement of transmitters and receivers,
   the use of minimum power required to provide the needed service, and the use
   of highly directive transmitting and receiving antenna systems, to prevent
   interference to the reception of television STL, television intercity relay,
   and other CARS stations.

   (c)(1) Radio Astronomy and Radio Research Installations. In order to
   minimize harmful interference at the National Radio Astronomy Observatory
   site located at Green Bank, Pocahontas County, W. Va., and at the Naval
   Radio Research Observatory at Sugar Grove, Pendleton County, W.Va., an
   applicant for authority to construct a CARS station, except a CARS pickup
   station, or for authority to make changes in the frequency, power, antenna
   height, or antenna directivity of an existing 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, Post Office Box No. 2, Green Bank, WV
   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 application, 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.

   (2) Any applicant for a new permanent base or fixed 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 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.

   (i) 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 transmit 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 isotropic 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.

   (ii) 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.

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

   (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 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 caculated 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 recomended 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 km (1.5 statute miles);

   (ii) Stations within 4.8 km (3 statute miles) 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 km (10 statute miles) with 1 kW or more ERP in the
   primary plane of polarization in the azimuthal direction of the Table
   Mountain Radio Receiving Zone;

   (iv) Stations within 80 km (50 statute miles) with 25 kW or more ERP in the
   primary plane of polarization in the azimuthal direction of the Table
   Mountain Radio 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, D.C.
   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 section
   0.121(c) of the Commission's Rules and also meets the criteria outlined in
   paragraphs (f)(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) Protection to the Federal Government's receive earth station perations
   in the Denver, Colorado and Washington D.C. areas in the 17,800 to 19,700
   MHz band.

   (1) With the exception of applicants for a station authorization to operate
   within a 5 km radius of 39 °40'23" N Lat. and 105 °13'03" W Long (Morrison,
   CO), applicants will not be authorized to operate within a 50 km radius of
   39 °43'00" N Lat. and 104 °46'00" W Long. (Denver, CO) and within a 50 km
   radius of 38 °48'00" N Lat. and 76 °52'00" W Long. (Washington, DC).

   (2) To minimize or avoid harmful interference to Government Satellite Earth
   Stations located in the Denver, Colorado and Washington, DC areas, any
   application for a new station license to operate in the 17.8-19.7 GHz band,
   or for modification of an existing station license in this band which would
   change the frequency, power, emission, modulation, polarization, antenna
   height or directivity, or location of such a station, must be coordinated
   with the Federal Government by the Commission before an authorization will
   be issued, if the station or proposed station is located in whole or in part
   within any of the areas defined by the following rectangles or circles:

   (i) A circular area within a 5 km radius of 39 °40'23" N Lat. and 105 °13'03"
   W Long. (Morrison, CO)

   (ii) Within the rectangular areas defined as follows (vicinity of Denver,
   CO):

   Rectangle 1:

   41 °30'00" N. Lat. on the north

   103 °10'00" W. Long. on the east

   38 °30'00" N. Lat. on the south

   106 °30'00" W. Long. on the west

   Rectangle 2:

   38 °30'00" N. Lat. on the north

   105 °00'00" W. Long. on the east

   37 °30'00" N. Lat. on the south

   105 °50'00" W. Long. on the west

   Rectangle 3:

   40 °08'00" N. Lat. on the north

   107 °00'00" W. Long. on the east

   39 °56'00" N. Lat. on the south

   107 °15'00" W. Long. on the west

   (iii) Within the rectangle and circle areas as follows (vicinity of
   Washington, DC):

   Rectangle

   38 °40'00" N. Lat. on the north

   78 °50'00" W. Long. on the east

   38 °10'00" N. Lat. on the south

   79 °20'00" W. Long. on the west or

   or

   (iv) Within a radius of 178 km of 38 °48'00" N. Lat. / 76 °52'00" W. Long.

   Note to  Sec. 78.19: The coordinates cited in this section are specified in terms
   of the “North American Datum of 1983 (NAD 83)” with an accuracy of −30
   meters with respect to the “National Spacial Reference System.”

   [ 37 FR 3292 , Feb. 12, 1972, as amended at  37 FR 15926 , Aug. 8, 1972;  37 FR 26733 , Dec. 15, 1972;  38 FR 1920 , Jan. 19, 1973;  42 FR 33037 , June 29, 1977;
    44 FR 77167 , Dec. 31, 1979;  45 FR 78694 , Nov. 26, 1980;  50 FR 32418 , Aug.
   12, 1985;  50 FR 40863 , Oct. 7, 1985;  50 FR 45406 , Oct. 31, 1985;  58 FR 44952 , Aug. 25, 1993;  61 FR 8478 , Mar. 5, 1996;  62 FR 55533 , 55538, Oct. 27,
   1997;  69 FR 57862 , Sept. 28, 2004;  70 FR 31373 , June 1, 2005]