Sec. 27.61  Quiet zones.

    Quiet zones are those areas where it is necessary to restrict 
radiation so as to minimize possible impact on the operations of radio 
astronomy or other facilities that are highly sensitive to interference. 
The areas involved and procedures required are as follows:
    (a) NRAO, NRRO. The requirements of this paragraph are intended to 
minimize possible 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. WCS licensees planning to 
construct and operate a new or modified WCS station at a permanent fixed 
location within the area bounded by N.39 deg.15' on the north, 
W.78 deg.30' on the east, N.37 deg.30' on the south, and W.80 deg.30' on 
the west must notify the Director, National Radio Astronomy Observatory, 
Post Office Box No. 2, Green Bank, WV 24944, in writing, of the 
technical details of the proposed operation. The notification must 
include the geographical coordinates of the antenna location, the 
antenna height, antenna directivity (if any), the channel, the emission 
type and power.
    (b) Table Mountain. The requirements of this paragraph are intended 
to minimize possible interference at the Table Mountain Radio Receiving 
Zone of the Research Laboratories of the U.S. Department of Commerce 
located in Boulder County, Colorado.
    (1) WCS licensees planning to construct and operate a new or 
modified WCS station at a permanent fixed location in the vicinity of 
Boulder County, Colorado are advised to give consideration, prior to 
filing applications, to the need to protect the Table Mountain Radio 
Receiving Zone from interference. To prevent degradation of the present 
ambient radio signal level at the site, the U.S. 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 deg.07'50'' North Latitude, 105 deg.14'40'' 
West Longitude) resulting from new assignments (other than mobile 
stations) or from the modification or relocation of existing facilities 
do not exceed the values given in Table C-3.

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           Table C-3--Field Strength Limits for Table Mountain          
------------------------------------------------------------------------
         Frequency range            Field strength    Power flux density
------------------------------------------------------------------------
890 to 3000 MHz.................  1 mV/m............  -85.8 dBW/m \2\   
------------------------------------------------------------------------
Note: Equivalent values of power flux density are calculated assuming   
  free space characteristic impedance of 376.7 (120). (120).                                                 

    (2) Advance consultation is recommended, particularly for WCS 
licensees that have no reliable data to indicate whether the field 
strength or power flux density figures in the above table would be 
exceeded by their proposed radio facilities. In general, coordination is 
recommended for:
    (i) Stations located within 2.4 kilometers (1.5 miles);
    (ii) Stations located within 4.8 kilometers (3 miles) transmitting 
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 located within 16 kilometers (10 miles) transmitting 
with 1 kW or more ERP in the primary plane of polarization in the 
azimuthal direction of Table Mountain Radio Receiving Zone;
    (iv) Stations located within 80 kilometers (50 miles) transmitting 
with 25 kW or more ERP in the primary plane of polarization in the 
azimuthal direction of Table Mountain Receiving Zone.
    (3) WCS licensees are urged to communicate with the Radio Frequency 
Management Coordinator, U.S. Department of Commerce, Research Support 
Services NOAAR/E5X2, Boulder Laboratories, Boulder, CO 80303; telephone 
(303) 497-6548, in advance of construction and operation of such 
facilities.
    (c) Federal Communications Commission protected field offices. The 
requirements of this paragraph are intended to minimize possible 
interference to FCC monitoring activities.
    (1) WCS licensees planning to construct and operate a new or 
modified WCS station at a permanent fixed location in the vicinity of an 
FCC protected field office are advised to give consideration to the need 
to avoid interfering with the monitoring activities of that office. FCC 
protected field offices are listed in Sec. 0.121 of this chapter.
    (2) Applications for stations (except mobile stations) that could 
produce on any channel a direct wave fundamental field strength of 
greater than 10 mV/m (-65.8 dBW/m \2\ power flux density assuming a free 
space characteristic impedance of 120) in the 
authorized bandwidth at the protected field office must be examined by 
WCS licensees to determine the potential for interference with 
monitoring activities.
    (3) In the event that the calculated field strength exceeds 10 mV/m 
at the protected field office site, or if there is any question whether 
field strength levels might exceed that level, advance consultation with 
the FCC to discuss possible measures to avoid interference to monitoring 
activities should be considered. WCS licensees may communicate with: 
Chief, Compliance and Information Bureau, Federal Communications 
Commission, Washington, DC 20554.
    (4) Advance consultation is recommended for WCS licensees that have 
no reliable data to indicate whether the field strength or power flux 
density figure indicated would be exceeded by their proposed radio 
facilities. In general, coordination is recommended for:
    (i) Stations located within 2.4 kilometers (1.5 miles);
    (ii) Stations located within 4.8 kilometers (3 miles) with 50 watts 
or more average effective radiated power (ERP) in the primary plane of 
polarization in the azimuthal direction of the protected field offices.
    (iii) Stations located within 16 kilometers (10 miles) with 1 kW or 
more average ERP in the primary plane of polarization in the azimuthal 
direction of the protected field office;
    (iv) Stations located within 80 kilometers (50 miles) with 25 kW or 
more average ERP in the primary plane of polarization in the azimuthal 
direction of the protected field office;
    (5) Advance coordination for stations transmitting on channels above 
1000 MHz is recommended only if the proposed station is in the vicinity 
of a protected field office designated as a satellite monitoring 
facility in Sec. 0.121 of this chapter.
    (6) The FCC will not screen applications to determine whether 
advance consultation has taken place. However,

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such consultation may serve to avoid the need for later modification of 
the authorizations of stations that interfere with monitoring activities 
at protected field offices.