Peak envelope power is the average power supplied to the antenna transmission line by a transmitter during one radio frequency cycle at the crest of the modulation envelope, under normal operating conditions.

PEP was often used in non-broadcast amplitude modulation (AM) applications because it most accurately described the potential of mobile transmitters to interfere with each other. Its use is now somewhat deprecated, with the average transmitter power output (or sometimes effective radiated power) now typically being preferred.

See also: Federal Standard 1037C