§  73.807   Minimum distance separation between stations.

   Minimum separation requirements for LPFM stations are listed in the
   following paragraphs. Except as noted below, an LPFM station will not
   be authorized unless the co-channel, and first- and second-adjacent
   channel separations are met. An LPFM station need not satisfy the
   third-adjacent channel separations listed in paragraphs (a) through (c)
   of this section in order to be authorized. The third-adjacent channel
   separations are included for use in determining for purposes of § 73.810
   which third-adjacent channel interference regime applies to an LPFM
   station. Minimum distances for co-channel and first-adjacent channel
   are separated into two columns. The left-hand column lists the required
   minimum separation to protect other stations and the right-hand column
   lists (for informational purposes only) the minimum distance necessary
   for the LPFM station to receive no interference from other stations
   assumed to be operating at the maximum permitted facilities for the
   station class. For second-adjacent channel, the required minimum
   distance separation is sufficient to avoid interference received from
   other stations.

   (a)(1) An LPFM station will not be authorized initially unless the
   minimum distance separations in the following table are met with
   respect to authorized FM stations, applications for new and existing FM
   stations filed prior to the release of the public notice announcing an
   LPFM window period, authorized LPFM stations, LPFM station applications
   that were timely-filed within a previous window, and vacant FM
   allotments. LPFM modification applications must either meet the
   distance separations in the following table or, if short-spaced, not
   lessen the spacing to subsequently authorized stations.
   Station class protected by LPFM Co-channel minimum separation
   (km) First-adjacent channel
   minimum separation
   (km) Second and
   third adjacent
   channel
   minimum
   separation
   (km)
   Required For no
   interference received from max. class
   facility Required For no
   interference
   received
   from
   max. class
   facility Required
   LPFM 24 24 14 14 None
   D 24 24 13 13 6
   A 67 92 56 56 29
   B1 87 119 74 74 46
   B 112 143 97 97 67
   C3 78 119 67 67 40
   C2 91 143 80 84 53
   C1 111 178 100 111 73
   C0 122 193 111 130 84
   C 130 203 120 142 93

   (2) LPFM stations must satisfy the second-adjacent channel minimum
   distance separation requirements of paragraph (a)(1) of this section
   with respect to any third-adjacent channel FM station that, as of
   September 20, 2000, broadcasts a radio reading service via a subcarrier
   frequency.

   (b) In addition to meeting or exceeding the minimum separations in
   paragraph (a) of this section, new LPFM stations will not be autorized
   in Puerto Rico or the Virgin Islands unless the minimum distance
   separations in the following tables are met with respect to authorized
   or proposed FM stations:
   Station class protected by LPFM Co-channel minimum separation (km)
   First-adjacent channel
   minimum separation
   (km) Second and
   third adjacent
   channel
   minimum
   separation
   (km)--required
   Required For no
   interference received from max. class
   facility Required For no
   interference
   received
   from
   max. class
   facility
   A 80 111 70 70 42
   B1 95 128 82 82 53
   B 138 179 123 123 92

   Note to paragraphs (a) and (b): Minimum distance separations towards
   "grandfathered" superpowered Reserved Band stations are as specified.
   Full service FM stations operating within the reserved band (Channels
   201-220) with facilities in excess of those permitted in § 73.211(b)(1)
   or (b)(3) shall be protected by LPFM stations in accordance with the
   minimum distance separations for the nearest class as determined under
   § 73.211. For example, a Class B1 station operating with facilities that
   result in a 60 dBu contour that exceeds 39 kilometers but is less than
   52 kilometers would be protected by the Class B minimum distance
   separations. Class D stations with 60 dBu contours that exceed 5
   kilometers will be protected by the Class A minimum distance
   separations. Class B stations with 60 dBu contours that exceed 52
   kilometers will be protected as Class C1 or Class C stations depending
   upon the distance to the 60 dBu contour. No stations will be protected
   beyond Class C separations.

   (c) In addition to meeting the separations specified in paragraphs (a)
   and (b), LPFM applications must meet the minimum separation
   requirements in the following table with respect to authorized FM
   translator stations, cutoff FM translator applications, and FM
   translator applications filed prior to the release of the Public Notice
   announcing the LPFM window period.
   Distance to FM translator 60 dBu contour Co-channel minimum separation
   (km) First-adjacent channel
   minimum separation (km) Second and
   third adjacent
   channel
   minimum
   separation
   (km)--required
   Required For no
   interference
   received Required For no
   interference
   received
   13.3 km or greater 39 67 28 35 21
   Greater than 7.3 km, but less than 13.3 km 32 51 21 26 14
   7.3 km or less 26 30 15 16 8

   (d) Existing LPFM stations which do not meet the separations in
   paragraphs (a) through (c) of this section may be relocated provided
   that the separation to any short-spaced station is not reduced.

   (e)(1) Waiver of the second-adjacent channel separations. The
   Commission will entertain requests to waive the second-adjacent channel
   separations in paragraphs (a) through (c) of this section on a
   case-by-case basis. In each case, the LPFM station must establish,
   using methods of predicting interference taking into account all
   relevant factors, including terrain-sensitive propagation models, that
   its proposed operations will not result in interference to any
   authorized radio service. The LPFM station may do so by demonstrating
   that no actual interference will occur due to intervening terrain or
   lack of population. The LPFM station may use an undesired/desired
   signal strength ratio methodology to define areas of potential
   interference.

   (2) Interference. (i) Upon receipt of a complaint of interference from
   an LPFM station operating pursuant to a waiver granted under paragraph
   (e)(1) of this section, the Commission shall notify the identified LPFM
   station by telephone or other electronic communication within one
   business day.

   (ii) An LPFM station that receives a waiver under paragraph (e)(1) of
   this section shall suspend operation immediately upon notification by
   the Commission that it is causing interference to the reception of an
   existing or modified full-service FM station without regard to the
   location of the station receiving interference. The LPFM station shall
   not resume operation until such interference has been eliminated or it
   can demonstrate to the Commission that the interference was not due to
   emissions from the LPFM station. Short test transmissions may be made
   during the period of suspended operation to check the efficacy of
   remedial measures.

   (f) Commercial and noncommercial educational stations authorized under
   subparts B and C of this part, as well as new or modified commercial FM
   allotments, are not required to adhere to the separations specified in
   this rule section, even where new or increased interference would be
   created.

   (g) International considerations within the border zones. (1) Within
   320 km of the Canadian border, LPFM stations must meet the following
   minimum separations with respect to any Canadian stations:
   Canadian station class Co-channel
   (km) First-adjacent channel
   (km) Second-
   adjacent
   channel
   (km) Third-adjacent channel
   (km) Intermediate
   frequency (IF)
   channel
   (km)
   A1 & Low Power 45 30 21 20 4
   A 66 50 41 40 7
   B1 78 62 53 52 9
   B 92 76 68 66 12
   C1 113 98 89 88 19
   C 124 108 99 98 28

   (2) Within 320 km of the Mexican border, LPFM stations must meet the
   following separations with respect to any Mexican stations:
   Mexican station class Co-channel
   (km) First-adjacent channel
   (km) Second- and third-adjacent channel
   (km) Intermediate
   frequency (IF)
   channel
   (km)
   Low Power 27 17 9 3
   A 43 32 25 5
   AA 47 36 29 6
   B1 67 54 45 8
   B 91 76 66 11
   C1 91 80 73 19
   C 110 100 92 27

   (3) The Commission will notify the International Telecommunications
   Union (ITU) of any LPFM authorizations in the US Virgin Islands. Any
   authorization issued for a US Virgin Islands LPFM station will include
   a condition that permits the Commission to modify, suspend or terminate
   without right to a hearing if found by the Commission to be necessary
   to conform to any international regulations or agreements.

   (4) The Commission will initiate international coordination of a LPFM
   proposal even where the above Canadian and Mexican spacing tables are
   met, if it appears that such coordination is necessary to maintain
   compliance with international agreements.

   (5)(i) LPFM stations located within 125 kilometers of the Mexican
   border are limited to 50 watts (0.05 kW) ERP, a 60 dBu service contour
   of 8.7 kilometers and a 34 dBu interfering contour of 32 kilometers in
   the direction of the Mexican border. LPFM stations may operate up to
   100 watts in all other directions.

   (ii) LPFM stations located between 125 kilometers and 320 kilometers
   from the Mexican border may operate in excess of 50 watts, up to a
   maximum ERP of 100 watts. However, in no event shall the location of
   the 60 dBu contour lie within 116.3 kilometers of the Mexican border.

   (iii) Applications for LPFM stations within 320 kilometers of the
   Canadian border may employ an ERP of up to a maximum of 100 watts. The
   distance to the 34 dBu interfering contour may not exceed 60 kilometers
   in any direction.

   [ 78 FR 2102 , Jan. 9, 2013, as amended at  85 FR 35573 , June 11, 2020]