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 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 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

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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 deg.07'50' N Latitude, 105 deg.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  
                Frequency range                  (mV/m) in     \2\) 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=120 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

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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) 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.
[ 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]