Peak envelope power

The United States FCC uses PEP to set maximum power standards for radio transmitters.

PEP is also equal to average power in a steady FM, FSK, or RTTY transmission.

Most modern amateur transceivers sample PEP to adjust power, using an ALC (automatic level control) system.

This distortion commonly appears as envelope power overshoot on leading edges, and sometimes causes negative carrier shift on AM.

Some more poorly designed transceivers have a short term envelope power overshoot several times the steady-state PEP setting.

Representation of the peak envelope power (PEP) using the example of an AM-modulated signal. The PEP is the power area shown in red.