Peak Envelope Power

Peak Envelope power is most commonly used in RF signals and is a measure of AM signals' energy. It can be defined as the traces of extreme points in an RF signal. A modulated RF varying signals have different instantaneous power levels over time. The largest point where the largest magnitude occurs on both sides of a modulated signal is called the voltage signal's peak. Average power is the most obvious way to look at the power of a signal, and in a non-constant continuous signal, root means square power is not enough, and peak power is required. This practice is very common in RF signals as PEP determines the capability of RF amplifiers.

Here we first, need to look into peak and root mean square voltage. The peak voltage in a signal is a voltage at its highest point. Using the peak voltage, the RMS voltage can be determined using the formula as below:

 

And The Peak Envelope Power Can Be Calculated As Below:

 

 

When imposed on an AM signal, a no audio signal results in a rectangular cased modulated a signal whose voltage is half the peak voltage and thus resulting in a quarter power of that signal.

To better understand the envelope is the outer covering in a modulated signal, one envelope's power is the peak envelope power. The various factors can be observed in the figures below:

 

After finding the peak envelope power, we compare it with the carrier power. The ideal ratio between the PEP and Carrier power in radio signals for good transmission is considered to be 4:1. This factor is very closely related to percentage modulation which is calculated as below:

 

This gives a percentage overview of the modulated signal and helps determine if the signal is over or under modulated, thus giving a better understanding of PEP. An over-modulated signal would have zero energy periods or the distorted regions where PEP is almost zero, as seen in the figure below.