§ 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
   NCE-FM channel Distance (kilometers) NCE-FM channel Distance (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 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 § 73.684, “Prediction of
   coverage,” using the F(50,50) curves in Figure 9, § 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 Figures 1 and 2, § 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 (§ 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�° relative to the azimuth from the FM
   transmitter site to the TV Channel 6 transmitter site, counterclockwise to
   250�° 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�° clockwise to 110�° and from
   250�° clockwise to 290�°.

   (iv) The distances to the applicable NCE-FM interference contours will be
   predicted according to the procedures specified in § 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, § 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
   § 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:

   (i) If any part of the predicted interference area is within the Grade A
   field strength contour (§ 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 (§ 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 (§ 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
   § 73.684, “Prediction of coverage,” using the F(50,50) curves in Figure 9,
   § 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 will be predicted according to the
   procedures  specified  in § 73.684, “Prediction of coverage,” using the
   F(50,10) curves in Figure 9a, § 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 § 73.333 Figure 1a would overlap the 40 dBu contour based
   on the F(50,50) curves in § 73.699, Figure 9.

   [ 50 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]

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