LPFM in Puerto Rico and the US Virgin Islands

UPDATED MAY 12, 2020

In the US Virgin Islands and Puerto Rico, full power FM stations operate at field strengths well above normal operating class parameters in the mainland. As a result, LPFM rules have always had different spacing requirements. While the protections between full power stations within PR and VI follow some really strange service and interference contours (based on the classes of BOTH stations), LPFM is a little more straightforward. However, the engineering rules are different than on the mainland.

LPFM stations in this area are the normal field strength (5.6 at 60dBu) for service contour and like LPFM stations on the mainland, interference contour protections vary for class B1 and B opposing stations.  Like the mainland, the class B1 and B stations will have protected service contours out to 57dBu and 54dBu respectively, however all three classes (A, B1 and B) will use the same interference contours.

Service contours for full service FM stations in PR & VI

Because PR and VI are in Zone I-A, class C, C0, C1, C2 and C3 stations are not available. Translators not being used for AM or FM fill-in services are limited to 250 watts at 32m HAAT (7.3 km service contour).

  • Class A full facilities are 6 kW at 240 meters HAAT (60 dBu service contour).
  • Class B1 full facilities are 25 kW at 150 meters HAAT (57 dBu service contour).
  • Class B full facilities are 50 kW at 472 meters HAAT (54 dBu service contour).

Remember, the 20 km buffer zone around the full power station’s service contour for co-channel and first adjacent channel is also in effect in Puerto Rico and the Virgin Islands.  

Distance seperation charts for LP-100 in Puerto Rico/Virgin Islands

FM stations in the British Virgin Islands

There are no specific FCC rules related to protecting FM stations in the British Virgin Islands (BVI).

LPFM stations, especially those in the US Virgin Islands may be required to protect FM operations in the BVI. All LPFM applications in PR & VI will be coordinated through the International Telecommunications Union. A foreign administration may object to the assignment, more likely in cases where the 34 dBu interfering contour reaches land in the BVI. The FCC provides information on BVI FM stations which do appear in REC’s databases (look for the country code BV). It’s only as good as the information the FCC receives from the ITU and/or the BVI administration. REC does our best to protect these stations on Channel Searches but we always recommend additional investigation on applications in this area. 

FM frequencies believed to be in use in the BVI include: 88.5, 90.9, 91.7, 92.3, 94.1, 94.3, 97.3, 100.5, 103.7 and 106.9.