Part 73, Subpart G, Section 73.813 is a regulation that clarifies the standard used for determining height above average terrain (HAAT).
Overview
Main article: Height above average terrain.
HAAT is calculated by looking at the elevations in 8 equally spaced directions (every 45 degrees) at 50 equally-spaced points at a distance between 3 and 16 kilometers (about 2 to 10 miles) from the LPFM antenna site and comparing that with the height of the radiation center of the antenna above ground level plus the ground elevation at the site.
There is an alternate method used by certain FM translators that looks at HAAT along 12 equally-spaced directions.
This rule refers to a regulation in the full-power FM broadcast rules to clarify that LPFM will use the 8 equally-spaced directions method.
Regulatory history
This rule was originally enacted in the 2000 LPFM Report and Order and has not been amended since.
Text of regulation 47 CFR §73.813
§ 73.813 Determination of antenna height above average terrain (HAAT).
HAAT determinations for LPFM stations will be made in accordance with the procedure detailed in § 73.313(d) of this part.