Maximum usable frequency
(MUF): In radio transmission
from the regular ionized layers of the ionosphere
, the upper frequency
limit that can be used for transmission between two points at a specified time
Note: MUF is a median frequency applicable to 50% of the days of a month, as opposed to 90% cited for the lowest usable high frequency (LUF) and the optimum traffic frequency (FOT).
Source: from Federal Standard 1037C and from MIL-STD-188