Note 1: The Carson bandwidth rule is expressed by the relation CBR = 2(Δf + f m) where CBR is the bandwidth requirement, Δf is the carrier peak deviation frequency, and f m is the highest modulating frequency.
Note 2: The Carson bandwidth rule is often applied to transmitters, antennas, optical sources, receivers, photodetectors, and other communications system components.
Source: from Federal Standard 1037C