Sec. 73.525  TV Channel 6 protection.

    The provisions of this section apply to all applications for 
construction permits for new or modified facilities for a NCE-FM station 
on Channels 200-220 unless the application is accompanied by a written 
agreement between the NCE-FM applicant and each affected TV Channel 6 
broadcast station concurring with the proposed NCE-FM facilities.
    (a) Affected TV Channel 6 Station.
    (1) An affected TV Channel 6 station is a TV broadcast station which 
is authorized to operate on Channel 6 that is located within the 
following distances of a NCE-FM station operating on Channels 201-220:

                                 Table A                                
------------------------------------------------------------------------
                      Distance                             Distance     
 NCE-FM channel     (kilometers)      NCE-FM channel     (kilometers)   
------------------------------------------------------------------------
201............             265               211                196    
202............             257               212                195    
203............             246               213                193    
204............             235               214                187    
205............             225               215                180    
206............             211               216                177    
207............             196               217                174    
208............             196               218                166    
209............             196               219                159    
210............             196               220                154    
------------------------------------------------------------------------

    (2) Where a NCE-FM application has been accepted for filing or 
granted, the subsequent acceptance of an application filed by a relevant 
TV Channel 6 station will not require revision of the pending NCE-FM 
application or the FM station's authorized facilities, unless the 
provisions of paragraph (e)(3) of this section for TV translator or 
satellite stations apply.
    (b) Existing NCE-FM Stations. (1) A NCE-FM station license 
authorized to operate on channels 201-220 as of December 31, 1984, or a 
permittee, granted a construction permit for a NCE-FM station as of 
December 31, 1984, are not subject to this section unless they propose 
either:
    (i) To make changes in operating facilities or location which will 
increase predicted interference as calculated under paragraph (e) of 
this section to TV Channel 6 reception in any direction; or,
    (ii) To increase its ratio of vertically polarized to horizontally 
polarized transmissions.
    (2) Applicants must comply with the provision of paragraphs (c) or 
(d) of this section unless the application for modification demonstrates 
that, for each person predicted to receive new interference as a result 
of the change, existing predicted interference to two person will be 
eliminated. Persons predicted to receive new interference are those 
located outside the area predicted to receive interference from the 
station's currently authorized facilities (``existing predicted 
interference area'') but within the area predicted to receive 
interference from the proposed facilities (``proposed predicted 
interference area''). Persons for whom predicted interference will be 
eliminated are those located within the existing predicted interference 
area and outside the proposed predicted interference area.
    (i) In making this calculation, the provisions contained at 
paragraph (e) will be used except as modified by paragraph (b)(3) of 
this section.
    (ii) The following adjustment to the population calculation may be 
made: up to 1,000 persons may be subtracted from the population 
predicted to receive new interference if, for each person substracted, 
the applicant effectively installs two filters within 90 days after 
commencing program tests with the proposed facilities and, no later than 
45 days thereafter, provides the affected TV Channel 6 station (as 
defined in paragraph (a) of this section) with a certification 
containing sufficient information to permit verification of such 
installation. The required number of filters will be installed on 
television receivers located within the predicted interference area; 
provided that half of the installations are within

[[Page 154]]

the area predicted to receive new interference.
    (3) Where an NCE-FM applicant wishes to operate with facilities in 
excess of that permitted under the provisions of paragraphs (c) or (d) 
of this section, by proposing to use vertically polarized transmissions 
only, or to increase its ratio of vertically to horizontally polarized 
transmissions, the affected TV Channel 6 station must be given an option 
to pay for the required antenna and, if it takes that option, the NCE-FM 
vertically polarized component of power will be one half (-3 dB) that 
which would be allowed by the provisions of paragraph (e)(4) of this 
section.
    (4) Applications for modification will include a certification that 
the applicant has given early written notice of the proposed 
modification to all affected TV Channel 6 stations (as defined in 
paragraph (a) of this section).
    (5) Where the NCE-FM station demonstrates in its application that it 
must make an involuntary modification (e.g., due to loss of its 
transmitter site) that would not otherwise be permitted under this 
section, its application will be considered on a case-by-case basis. In 
such cases, the provisions of paragaph (b)(3) of this section do not 
apply.
    (c) New NCE-FM Stations. Except as provided for by paragraph (d) of 
this section, applicants for NCE-FM stations proposing to operate on 
Channels 201-220 must submit a showing indicating that the predicted 
interference area resulting from the proposed facility contains no more 
than 3,000 persons.
    (1) In making these calculations, the provisions in paragraph (e) of 
this section will be used.
    (2) The following adjustment to population may be made: up to 1,000 
persons may be subtracted from the population within the predicted 
interference area if, for each person subtracted, the applicant 
effectively installs one filter within 90 days after commencing program 
tests and, no later than 45 days thereafter, provides the affected TV 
Channel 6 station with a certification containing sufficient information 
to permit verification of such installation. The required number of 
filters will be installed on television receivers located within the 
predicted interference area.
    (d) Collocated Stations. As an alternative to the provisions 
contained in paragraphs (b) and (c) of this section, an application for 
a NCE-FM station operating on Channels 201-220 and located at 0.4 
kilometer (approximately 0.25 mile) or less from a TV Channel 6 station 
will be accepted under the following requirements:
    (1) The effective radiated power cannot exceed the following values:

                                 Table B                                
------------------------------------------------------------------------
 NCE-FM channel    Power (kilowatt)   NCE-FM channel    Power (kilowatt)
------------------------------------------------------------------------
201.............            1.1                211              26.3    
202.............            1.9                212              31.6    
203.............            3.1                213              38.0    
204.............            5.0                214              46.8    
205.............            8.3                215              56.2    
206.............           10.0                216              67.6    
207.............           12.0                217              83.2    
208.............           14.8                218             100.0    
209.............           17.8                219             100.0    
210.............           21.4                220             100.0    
------------------------------------------------------------------------

    (2) The NCE-FM application will include a certification that the 
applicant has coordinated its antenna with the affected TV station by 
employing either: The same number of antenna bays with radiation centers 
separated by no more than 30 meters (approximately 100 feet) 
verticially; or, the FM vertical pattern not exceeding the TV vertical 
pattern by more than 2dB.
    (e) Calculation of Predicted Interference Area and Population. 
Predictions of interference required under this section and calculations 
to determine the number of persons within a predicted interference area 
for NCE-FM operation on Channels 201-220 are made as follows:
    (1) The predicted interference area will be calculated as follows:
    (i) The distances to the TV Channel 6 field strength contours will 
be predicted according to the procedures specified in Sec. 73.684, 
``Prediction of coverage,'' using the F(50,50) curves in Figure 9, 
Sec. 73.699.
    (ii) For each TV Channel 6 field strength contour, there will be an 
associated F(50,10) FM interference contour, the value of which (in 
units of dBu) is defined as the sum of the TV Channel 6 field strength 
(in dBu) and the appropriate undesired-to-desired (U/D) signal ratio (in 
dB) obtained from

[[Page 155]]

Figures 1 and 2, Sec. 73.599, corresponding to the channel of the NCE-FM 
applicant and the appropriate F(50,50) field strength contour of the TV 
Channel 6 station.
    (iii) An adjustment of 6 dB for television receiving antenna 
directivity will be added to each NCE-FM interference contour at all 
points outside the Grade A field strength contour (Sec. 73.683) of the 
TV Channel 6 station and within an arc defined by the range of angles, 
of which the FM transmitter site is the vertex, from 110 deg. relative 
to the azimuth from the FM transmitter site to the TV Channel 6 
transmitter site, counterclockwise to 250 deg. relative to that azimuth. 
At all points at and within the Grade A field strength contour of the TV 
Channel 6 station, the 6 dB adjustment is applicable over the range of 
angles from 70 deg. clockwise to 110 deg. and from 250 deg. clockwise to 
290 deg..
    (iv) The distances to the applicable NCE-FM interference contours 
will be predicted according to the procedures specified in Sec. 73.313, 
``Prediction of Coverage,'' using the proposed antenna height and 
horizontally polarized, or the horizontal equivalent of the vertically 
polarized, effective radiated power in the pertinent direction and the 
F(50,10) field strength curves (Figure 1a, Sec. 73.333).
    (v) The predicted interference area will be defined as the area 
within the TV Channel 6 station's 47 dBu field strength contour that is 
bounded by the locus of intersections of a series of TV Channel 6 field 
strength contours and the applicable NCE-FM interference contours.
    (vi) In cases where the terrain in one or more directions departs 
widely from the surrounding terrain average (for example, an intervening 
mountain), a supplemental showing may be made. Such supplemental 
showings must describe the procedure used and should include sample 
calculations. The application must also include maps indicating the 
predicted interference area for both the regular method and the 
supplemental method.
    (vii) In cases where the predicted interference area to Channel 6 
television from a noncommercial educational FM station will be located 
within the 90 dBu F(50,50) contour of the television Channel 6 station, 
the location of the FM interfering contour must be determined using the 
assumption that the Channel 6 field strength remains constant at 90 dBu 
everywhere within the 90 dBu TV contour. The FM to Channel 6 U/D signal 
strength ratio specified in Sec. 73.599 corresponding to the Channel 6 
TV field strength of 90 dBu shall be used.
    (2) The number of persons contained within the predicted 
interference area will be based on data contained in the most recently 
published U.S. Census of Population and will be determined by plotting 
the predicted interference area on a County Subdivision Map of the state 
published for the Census, and totalling the number of persons in each 
County Subdivision (such as, Minor Civil Division (MCD), Census County 
Division (CCD), or equivalent areas) contained within the predicted 
interference area. Where only a portion of County Subdivision is 
contained within the interference area:
    (i) The population of all incorporated places or Census designated 
places will be subtracted from the County Subdivision population;
    (ii) Uniform distribution of the remaining population over the 
remaining area of the County Subdivision will be assumed in determining 
the number of persons within the predicted interference area in 
proportion to the share of the remaining area of the County Subdivision 
that lies within the predicted interference area; and,
    (iii) The population of the incorporated places or Census designated 
places contained within the predicted interference area will then be 
added to the total, again assuming uniform distribution of the 
population within the area of each place and adding a share of the 
population proportional to the share of the area if only a portion of 
such a place is within the predicted interference area.
    (iv) At the option of either the NCE-FM applicant or an affected TV 
Channel 6 station which provides the appropriate analysis, more detailed 
population data may be used.
    (3) Adjustments to the population calculated pursuant to paragraph 
(e)(2) of this section may be made as follows:

[[Page 156]]

    (i) If any part of the predicted interference area is within the 
Grade A field strength contour (Sec. 73.683) of a TV translator station 
carrying the affected TV Channel 6 station, the number of persons within 
that overlap area will be subtracted, provided the NCE-FM construction 
permit and license will contain the following conditions:
    (A) When the TV translator station ceases to carry the affected TV 
Channel 6 station's service and the cessation is not the choice of the 
affected TV Channel 6 station, the NCE-FM station will modify its 
facilities, within a reasonable transition period, to meet the 
requirements of this section which would have applied if no adjustment 
to population for translator service had been made in its application.
    (B) The transition period may not exceed 1 year from the date the 
NCE-FM station is notified by the TV Channel 6 station that the 
translator station will cease to carry the affected TV Channel 6 
station's service or 6 months after the translator station ceases to 
carry the affected TV Channel 6 station's service, whichever is earlier.
    (ii) If any part of the interference area is within the Grade B 
field strength contour (Sec. 73.683) of a satellite station of the 
affected TV Channel 6 station, the number of persons within the overlap 
area will be subtracted, provided the NCE-FM permit and license will 
contain the following conditions:
    (A) If the satellite station ceases to carry the affected TV Channel 
6 station's service and the cessation is not the choice of the affected 
TV Channel 6 station, the NCE-FM station will modify its facilities, 
within a reasonable transition period, to meet the requirements of this 
rule which would have applied if no adjustment to population for 
satellite station service had been made in its application.
    (B) The transition period may not exceed 1 year from the date the 
NCE-FM station is notified by the TV Channel 6 station that the 
satellite station will cease to carry the affected TV Channel 6 
stations's service or 6 months after the satellite station ceases to 
carry the affected TV Channel 6 station's service, whichever is earlier.
    (iii) If any part of the predicted interference area is located 
outside the affected TV Channel 6 station's Area of Dominant Influence 
(ADI), outside the Grade A field strength contour (Sec. 73.683), and 
within the predicted city grade field strength contour (73.685(a)) of a 
TV broadcast station whose only network affiliation is the same as the 
only network affiliation of the affected TV Channel 6 station, the 
number of persons within that part will be subtracted. (For purposes of 
this provision, a network is defined as ABC, CBS, NBC, or their 
successors.) In addition, the ADI of an affected TV Channel 6 station 
and the program network affiliations of all relevant TV broadcast 
stations will be assumed to be as they were on the filing date of the 
NCE-FM application or June 1, 1985, whichever is later.
    (iv) In calculating the population within the predicted interference 
area, an exception will be permitted upon a showing (e.g., as survey of 
actual television reception) that the number of persons within the 
predicted interference area should be reduced to account for persons 
actually experiencing co-channel or adjacent channel interference to 
reception of the affected TV Channel 6 station. The area within which 
such a showing may be made will be limited to the area calculated as 
follows:
    (A) The distances to the field strength contours of the affected TV 
Channel 6 station will be predicted according to the procedures 
specified in Sec. 73.684, ``Prediction of coverage,'' using the F(50,50) 
curves in Figure 9, Sec. 73.699.
    (B) For each field strength contour of the affected TV Channel 6 
station, there will be an associated co-channel or adjacent channel TV 
broadcast station interference contour, the value of which (in units of 
dBu) is defined as the sum of the affected TV Channel 6 station's field 
strength (in dBu) and the appropriate undesired-to-desired signal ratio 
(in dB) as follows:

Co-channel, normal offset, -22 dB
Co-channel, no offset, -39 dB
Adjacent channel, +12 dB

    (C) The distances to the associated co-channel or adjacent channel 
TV broadcast station interference contour

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will be predicted according to the procedures specified in Sec. 73.684, 
``Prediction of coverage,'' using the F(50,10) curves in Figure 9a, 
Sec. 73.699.
    (D) The area within which the showing of actual interference may be 
made will be the area bounded by the locus of intersections of a series 
of the affected TV Channel 6 station's field strength contours and the 
associated interference contours of the co-channel or adjacent channel 
TV broadcast station.
    (4) The maximum permissible effective radiated power (ERP) and 
antenna height may be adjusted for vertical polarity as follows:
    (i) If the applicant chooses to use vertically polarized 
transmissions only, the maximum permissible vertically polarized ERP 
will be the maximum horizontally polarized ERP permissible at the same 
proposed antenna height, calculated without the adjustment for 
television receiving antenna directivity specified in paragraph 
(e)(1)(iii) of this section, multiplied by either: 40 if the predicted 
interference area lies entirely outside the limits of a city of 50,000 
persons or more; or 10 if it does not.
    (ii) If the applicant chooses to use mixed polarity, the permissible 
ERP is as follows:

    [H+(V/A)] is no greater than P
Where:
    H is the horizontally polarized ERP in kilowatts for mixed polarity;
    V is the vertically polarized ERP in kilowatts for mixed polarity;
    A is 40 if the predicted interference area lies entirely outside the 
limits of a city of 50,000 persons or more, or 10 if it does not; and
    P is the maximum permitted horizontally polarized-only power in 
kilowatts.

    (f) Channel 200 Applications. No application for use of NCE-FM 
Channel 200 will be accepted if the requested facility would cause 
objectionable interference to TV Channel 6 operations. Such 
objectionable interference will be considered to exist whenever the 15 
dBu contour based on the F(50,10) curves in Sec. 73.333 Figure 1a would 
overlap the 40 dBu contour based on the F(50,50) curves in Sec. 73.699, 
Figure .

[50 9 FR 27963 , July 9, 1985;  50 FR 30187 , July 24, 1985;  50 FR 31379 , 
Aug. 2, 1985, as amended at  51 FR 26250 , July 22, 1986;  52 FR 25867 , 
July 9, 1987;  62 FR 51059 , Sept. 30, 1997]

    Effective Date Note:  At  62 FR 51059 , Sept. 30, 1997, Sec. 73.525 
was amended by adding paragraph (e)(1)(vii), effective Dec. 1, 1997.