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LPFM Report and Order: Difference between revisions
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The FCC made the LPFM service secondary and also provide protection to FM translator and booster stations. LPFM stations will also be required to protect vacant FM allotments. With that in mind, the FCC wanted to minimize the situations in which an LPFM station would be required to change channels or cease operating. LPFM stations will be required to protect full-service and translator stations using distance separation. In addition, LPFM stations in the reserved band (88.1~91.9) would also have to protect full-service and low power Channel 6 TV stations. | The FCC made the LPFM service secondary and also provide protection to FM translator and booster stations. LPFM stations will also be required to protect vacant FM allotments. With that in mind, the FCC wanted to minimize the situations in which an LPFM station would be required to change channels or cease operating. LPFM stations will be required to protect full-service and translator stations using distance separation. In addition, LPFM stations in the reserved band (88.1~91.9) would also have to protect full-service and low power Channel 6 TV stations. | ||
LPFM stations would not be required to eliminate interference caused to FM stations by their lawful operation. FM stations will also be required to address complaints of blanketing interference and will be subject to international agreements and must eliminate interference to primary Canadian or Mexican broadcast stations. | |||
In the rules, the FCC will include two distances in respect to co-channel and first-adjacent stations. The first distance is the required minimum separation distance that includes the interfering contour of the LPFM station, | In the rules, the FCC will include two distances in respect to co-channel and first-adjacent stations. The first distance is the required minimum separation distance that includes the interfering contour of the LPFM station, a 20 km "buffer zone" (towards full-service stations only) and the protected service contour of the incumbent station. The second distance will be the minimum distance where the LPFM station would likely not receive interference from the incumbent station. This consists of the interfering contour of the incumbent station plus the service contour of the LPFM station (no buffer zone). | ||
If a full-service station modifies their facility, the LPFM station may have to cease operations if the LPFM station causes interference in the full-service station's 70 dBu contour. | If a full-service station modifies their facility, the LPFM station may have to cease operations if the LPFM station causes interference in the full-service station's 70 dBu contour. | ||
=== Minimum distance separation requirements === | === Minimum distance separation requirements === | ||
==== Distance separation vs. contours ==== | |||
The FCC determined that distance separation, as opposed to using the contour overlap model used by FM translators would be used for LPFM stations. Recognizing that distance separation would preclude new LPFM stations in some areas, they were not persuaded that the potential benefit of some additional stations is substantial enough to warrant the preparation of more complex and costly engineering exhibits based on contours and the resulting delays in the authorization of the LPFM service. | |||
==== Establishment of distance separation tables ==== | |||
The FCC established distance separation tables for protections to full-service FM, Class D FM stations and other LPFM stations. A separate set of tables were established for protecting stations in Puerto Rico and the United States Virgin Islands due to the differences in the definition of service classes in those areas. A separate set of tables were established for LPFM stations in the reserved band to protect Channel 6 TV stations. | |||
Another set of tables were established to protect FM translator stations. The translator tables were set up in three tiers. The lower tier is for FM translators with a service contour of 7.3 kilometers or less, this value is consistent with the service contour size of non fill-in FM translators located east of the Mississippi as well as in California south of 40 degrees north latitude. The middle tier is for FM translators with a service contour greater than 7.3 kilometers, but less than or equal to 13.3 kilometers, which is consistent with non-fill in translators located in other parts of the country. The upper tier is for FM translators with a service contour that exceeds 13.3 kilometers. | |||
The FCC provided additional protections for about 20 grandfathered "super power" FM stations operating in the reserved band. These stations, which were originally authorized before 1962 operate at a power and height combination that exceeds those of their current service class. | |||
Separate tables will be established for the protection of FM facilities in Canada and Mexico. No tables were established for the protection of FM stations in the British Virgin Islands by LPFM stations in the United States Virgin Islands, but the FCC does advise that additional international coordination may be required. | |||
==== The 20 km "buffer zone" ==== | |||
In respect to full-service stations, the FCC included a 20 kilometer "buffer" to the distance separation requirements for co-channel and first-adjacent channels. The FCC established this buffer zone was intended to give full-service FM stations some room to move their facilities without impacting the LPFM station and it also affords the LPFM station an increased likelihood that its operation will not cause interference within a full-service station's community of license. The buffer zone applies only to the initial establishment of the LPFM station and subsequent moves by the LPFM station would either have to meet this distance or if already short-spaced, does not increase the short-spacing (e.g. moving the LPFM station closer to the full service station). | |||
=== Second and third adjacent channel protections === | === Second and third adjacent channel protections === | ||