For FM stations, it's 115 dBu based on "free space": http://www.scott-inc.com/html/73318.htm Mark On 6/20/06, Ernie Belanger <armtx at mhcable.com> wrote: > Does anyone have the formula used to determine the area around an transmitter site that a station is responsible to respond to and correct blanketing interference complaints. > > I'm dealing with a station with 45KW erp >