Section 73.807 - Minimum distance separation between stationsMinimum 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