Sec. 101.123  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 radio 
frequency interference.
    (a) In order to minimize possible harmful interference at the 
National Radio Astronomy Observatory site located at Green Bank, 
Pocohontas 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 temporary-fixed seeking a

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station license for a new station or to modify an existing station in a 
manner which would change either the frequency, power, antenna height or 
directivity, or location of such a station within the area boarded by 
39 deg.15' N. on the north, 78 deg.30' W. on the east, 37 deg.30' N. on 
the south, and 80 deg.30' W. on the west must 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, 
W. Va. 24944, in writing, of the technical particulars of the proposed 
station. Such notification must include the geographical coordinates of 
the antenna, antenna height, antenna directivity if any, proposed 
frequency, type of emission and power. In addition, the applicant must 
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 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.
    (b) 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 deg.07'50'' N. Latitude, 
105 deg.14'40'' W. Longitude), resulting from new assignments or from 
the modification or relocation of existing  facilities  do  not  exceed  
1 mV/m in the authorized bandwidth of service. (A field strength of 1 
mV/m is equivalent to a power flux density of 85.8 dBW/M\2\ assuming a 
free-space characteristic impedance of 376.7 ohms.)
    (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 would be exceeded by their 
proposed radio facilities. In such instances, the following is a 
suggested guide for determining whether coordination is recommended:
    (i) All stations within 2.4 km;
    (ii) Stations within 4.8 km with 50 watts or more effective radiated 
power (ERP) in the primary plane of polarization in the azimuthal 
direction of the Table Mountain Receiving Zone;
    (iii) Stations within 16 km with 1 kW or more ERP in the primary 
plane of polarization in the azimuthal direction of the Table Mountain 
Receiving Zone; or
    (iv) Stations within 80 km with 25 kW or more ERP in the primary 
plane of polarization in the azimuthal direction of the 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.
    (c) 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

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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 this chapter. 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/m2 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/m2) 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) 418-1100.
    (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;
    (ii) Stations within 4.8 kilometers 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 with 1 kW or more average ERP in 
the primary plane of polarization in the azimuthal direction of the 
Monitoring Station; or
    (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 this chapter and also meets the criteria outlined in 
paragraphs (c)(2) and (c)(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.