§ 73.807 is a core regulation in the Low Power FM radio service. This rule addresses the placement of LPFM stations in respect to other FM broadcast facilities. LPFM stations operating on reserved band FM frequencies (88.1~91.9 MHz) are also required to protect TV facilities on Channel 6 pursuant to § 73.825.
Protections to domestic FM stations
Main article: Required minimum distance separation to domestic FM facilities.
Other LPFM stations
LPFM stations may only be proposed where they are separated by other LPFM stations on the same channel by at least 24 kilometers (14.9 miles) and on first-adjacent channels by 14 kilometers (8.7 miles). LPFM stations are not required to protect other LPFM stations on second adjacent channels.
Full Service FM stations within the United States
In respect to full-service FM stations operating on the same or the first-adjacent channel of the LPFM, the minimum distance separations required are based on the standard interfering contour of the LPFM station and a distance that is 20 kilometers (12.4 miles) past the standard protected service contour of the full-service station. Each full-service FM service class has specific distances required for separation. This additional 20 kilometer "buffer zone" was adopted in the original LPFM Report and Order in order to assure minimal impacts on LPFM stations in the event that a full-service FM station had to make a modification of their facility.
LPFM stations are also required to protect full-service FM stations on second adjacent channels, however that requirement can be waived if a technical showing is made that the proposed LPFM facility does not cause any actual interference to listeners or potential listeners of the short-spaced second adjacent channel station or stations. In addition, LPFM stations must also protect FM stations on third adjacent channels in cases where the other FM station is carrying a Radio Reading Service. Second and third adjacent channel requirements do not include the 20 kilometer "buffer zone".
In 2011 with the enactment of the Local Community Radio Act of 2010 (LCRA), the use of minimum distance separation methodology and the actual distances that were codified in this rule at the time when the LCRA was enacted must be used. Because of that statutory requirement, the FCC is unable to give any waiver of the distance separation rules in respect to co-channel (same channel) and first-adjacent channel domestic FM facilities.
Class D stations
LPFM stations are required to protect Class D stations operating on the same channel as well as first and second adjacent channels. Second adjacent channel short-spacing can be waived in a manner similar to full-service FM stations.
Super-powered FM broadcast stations
FM stations operating in the reserved band (88.1~91.9 MHz), including class D stations, that are operating with parameters that exceed the maximum allowed for that service class will be protected at the service class that represents the parameters of the actual facility.
Puerto Rico and the U.S. Virgin Islands
Because of the differences in the maximum parameters of FM broadcast stations within Puerto Rico and the U.S. Virgin Islands, the required minimum distance separations from LPFM stations to full-service FM stations are are larger than those in the mainland United States. In Puerto Rico and the Virgin Islands, only classes A, B1 and B are available to full-service FM stations.
FM Translator Stations
In respect to FM stations, LPFM stations are classified into one of three "sub classes". The subclass is based on the translator's maximum effective radiated power (ERP) and overall height above average terrain. The sub-class is based on the average distance to the 60 dBu service contour. LPFM stations must protect FM translators on the same channel, first and second adjacent channels using minimum distance separation. Second adjacent channel spacing can be waived using the same method as waivers in respect to full-service FM stations.
While the FM translator service spacing requirements are not specifically mandated by the LCRA, the FCC has customarily not granted any waivers of distance separation on co-channel and first-adjacent channels, even if a finding of no interference is demonstrated. LPFM stations are required to protect FM translators using directional antennas as if they are using a nondirectional antenna.
Protections to foreign FM stations
Proposals for LPFM facilities located within 320 kilometers (198.8 miles) of the Canadian and Mexican borders will be coordinated with
Innovation,_Science_and_Economic_Development_Canada or Mexico's Instituto Federal de Telecomunicaciones in accordance with the appropriate international agreements. Normally, those countries will reply with either an acceptance or a objection of the proposed facility. As a result, a grant of an LPFM construction permit in a border zone may take longer than the time it takes for a proposal not involving international coordination. In some cases, the foreign administration may not timely reply to the Commission's proposal. In those cases, the FCC may grant the LPFM construction permit application with a condition that the proposal is still awaiting concurrence from the foreign administration, which can still object to the LPFM proposal. In those cases, the three years allowed to complete construction can be extended under the FCC's tolling policy.
Canada
Main article: Required minimum distance separation requirements to Canadian FM broadcast stations.
In 1991, the United States and |Canada reached an international agreement over the use of the FM channels in the border region. This agreement was updated in 1997 to reflect changes in service classes and to improve the lower powered facilities to operate in the region.
Minimum distance separations
LPFM stations are required to protect all Canadian FM facilities, including Canadian low power FM facilities through the use of a distance separation table based on the service class of the Canadian station. Protections are required on the same channel as well as first, second and third-adjacent channels. Unlike the rules for domestic FM facilities, there is no option to waive second (or third) adjacent channel protections. Waivers are not normally given for short-spaced stations where it can be shown that the LPFM station would not interfere with Canadian facilities even though one such waiver was granted to LPFM station WNUC-LP in Detroit.
LPFM stations are also required to protect Canadian facilities on their intermediate frequencies, which are those that are 53 or 54 channels (10.6 and 10.8 MHz) higher or lower than the LPFM's proposed operating channel.
Contour requirements
In addition to the distance separation requirements, LPFM stations operating within 320 kilometers (198.8 miles) of the Canadian border may not extend a 34 dBu interfering contour past 60 kilometers (37.3 miles) in any direction.
Mexico
Main article: Required minimum distance separation requirements to Mexican FM broadcast stations.
In 1992, the United States of America reached an agreement with the United Mexican States over the use of the FM channels in the border region. The agreement classifies both LPFM stations and FM translators as "LPFM" stations for the purposes of the agreement.
Minimum distance separations
LPFM stations are required to protect all Mexican FM facilities, including Mexican low power FM facilities through the use of a distance separation table based on the service class of the Mexican station. Protections are required on the same channel as well as first, second and third-adjacent channels. Unlike the rules for domestic FM facilities, there is no option to waive second (or third) adjacent channel protections. Waivers are not normally given for short-spaced stations where it can be shown that the LPFM station would not interfere with Mexican facilities.
Mexico Strip Zone
LPFM stations within 125 kilometers (77.6 miles) of the Mexican border are limited to 50 watts effective radiated power in the directions towards Mexico.
To determine the the area that requires this protection, plot a 125 kilometer radius around the proposed LPFM station and then draws lines from the LPFM station to all points where the 125 km radius intersects with the border. The area between those two or more lines is the area where the Mexico Strip Zone policies apply. In California, applicants need to be aware that Mexican territory extends into the Pacific Ocean to include the Coronado Islands located off the coast of the state of Baja California.
Contour requirements
In addition to the distance separation requirements, LPFM stations within 125 kilometers of Mexico may not extend a 60 dBu contour more than 8.7 kilometers (5.4 miles) towards the other country. In addition, the 34 dBu interfering contour cannot extend more than 32 kilometers (19.9 miles) towards the other country.
LPFM stations more than 125 km from the border may operate up to 100 watts in all directions. For stations exceeding 50 watts, the 60 dBu contour can not extend to any point within 116.3 kilometers (72.3 miles) within the Mexican border.
Caribbean nations
For foreign FM stations in the Caribbean region, the FCC does not have any specific bilateral or multilateral agreements with any other nation's administration. Therefore, there are no specific distance separation requirements to other FM facilities outside of the United States territories. The assignment of frequencies to LPFM stations in Puerto Rico and the U.S. Virgin Islands are also reported to the International Telecommunications Union's Master International Frequency Register. As a result, LPFM stations, especially those in the U.S. Virgin Islands may receive objections and interference complaints from other nations in the Caribbean region. Such objections and complaints would be lodged through the FCC's International Bureau, which will in turn contact the Media Bureau, which may order the LPFM station to cease operations. LPFM stations in the U.S. Virgin Islands should choose a channel that would not cause interference with FM stations in the British Virgin Islands.
Directional Antennas
Main article: Directional Antennas.
LPFM stations may use a directional antenna in order to achieve a facility that is compliant with an international agreement. LPFM stations that are using directional antennas solely for that purpose are not required to obtain a proof of performance and verifications from an engineer and a surveyor. Such directional antennas will be protected from FM translators as if they are operating with a nondirectional antenna.