FM translator stations are subject to specific height (HAAT) and power limitations, which are regulated by the Federal Communications Commission (FCC). Here’s an explanation of these limitations:
FM translator stations are subject to specific height (HAAT) and power limitations, which are regulated by the Federal Communications Commission (FCC). Here’s an explanation of these limitations:
- Height Above Average Terrain (HAAT): FM translator stations are typically limited in their HAAT, which is the height of their antenna above the average terrain in the area. The specific HAAT limitation depends on various factors, including the translator’s frequency, channel, and location. These limitations are in place to prevent interference with other stations and to ensure efficient use of the radio spectrum.
- Power Limitations: The FCC also imposes power limitations on FM translator stations. These limitations are designed to prevent signal overlap and interference with neighboring stations. The maximum power allowed for an FM translator station depends on its frequency and class.
It’s important to note that these limitations can vary depending on the specific circumstances and regulatory changes. Therefore, it’s essential for broadcasters to consult the FCC rules and guidelines or seek legal counsel to determine the precise HAAT and power limitations that apply to their FM translator station in their particular location and operating conditions. Failure to adhere to these limitations can result in regulatory issues and potential interference with other stations in the area.
When we examine FM translator stations, it’s important to distinguish between two types of FM translators, each subject to its own set of limitations:
1. Fill-in Stations:
- FM translators used for “fill-in” purposes within the service area of an AM or FM station.
- For translators providing fill-in service for FM stations, the translator’s protected service contour (e.g., 60, 57, or 54 dBu) must remain entirely within the protected service contour of the primary FM station.
- For translators providing fill-in service for AM stations, the translator’s contour must remain within the 2 millivolt per meter (mV/m) daytime contour of the AM station. In areas where the 2 mV/m contour does not extend 25 miles from the AM station, the translator’s 60 dBu contour can extend to 25 miles from the AM station.
- These translators can operate at up to 250 watts Effective Radiated Power (ERP) at any height above average terrain (HAAT), provided they stay within the service contour of the primary station and properly protect other broadcast stations, FM translators, and LPFM stations.
2. Translators to Extend Coverage:
- Translators with protected service contours extending outside of the protected service contour of the primary FM station being rebroadcast.
- These translators are typically used by non-commercial educational broadcasters, religious broadcasters, and municipal governments.
- They can also rebroadcast LPFM stations.
- ERP for these translators is limited based on maximum HAAT, and the limitations vary by geographic location (east of the Mississippi, California south of 40 degrees latitude, and other areas in the west). The maximum ERP can range from 10 watts to 250 watts at various HAAT levels.
- The specific power limitations are detailed in §74.1235(b) of the FCC rules.
To determine the maximum HAAT and ERP for a translator with a non-directional antenna, you can use the FCC’s HAAT Tool and consider the highest HAAT among the 12 radials. For directional antennas, the ERP along any of the 12 radials must not exceed the designated ERP for the HAAT shown along that radial.
Please note that LPFM stations use an 8-radial average calculation for HAAT, which can result in different power allowances compared to translators in certain locations.
These limitations ensure that FM translators operate within specific parameters to prevent interference and efficiently serve their intended areas.