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The peak-to-average power ratio (PAPR) is the peak amplitude squared (giving the peak power) divided by the RMS value squared (giving the average power). [1] It is the square of the crest factor. When expressed in decibels, crest factor and PAPR are equivalent, due to the way decibels are calculated for power ratios vs amplitude ratios.
Peak envelope power (PEP) is the average power over a single radio frequency cycle at the crest of the modulation. This is a Federal Communications Commission definition. PEP is normally considered the occasional or continuously repeating crest of the modulation envelope under normal operating conditions.
The power spectral density (PSD) of the signal describes the power present in the signal as a function of frequency, per unit frequency. Power spectral density is commonly expressed in SI units of watts per hertz (abbreviated as W/Hz). [2]
Peak values can be calculated from RMS values from the above formula, which implies V P = V RMS × √ 2, assuming the source is a pure sine wave. Thus the peak value of the mains voltage in the USA is about 120 × √ 2, or about 170 volts. The peak-to-peak voltage, being double this, is about 340 volts.
Peak power refers to the maximum of the instantaneous power waveform, which, for a sine wave, is always twice the average power. [16] [1] [17] [18] For other waveforms, the relationship between peak power and average power is the peak-to-average power ratio (PAPR).
Hence, the contribution to the average power of () coming from the component with frequency is . All these contributions add up to the average power of x ( t ) . {\displaystyle x(t).} Then the power as a function of frequency is 1 2 A k 2 , {\displaystyle {\tfrac {1}{2}}A_{k}^{2},} and its statistical cumulative distribution function S ( ν ...
In the important case that E(t) is sinusoidally varying at some frequency with peak amplitude E peak, E rms is /, with the average Poynting vector then given by: =. This is the most common form for the energy flux of a plane wave, since sinusoidal field amplitudes are most often expressed in terms of their peak values, and complicated problems ...
Using Wien's law, one finds a peak emission per nanometer (of wavelength) at a wavelength of about 500 nm, in the green portion of the spectrum near the peak sensitivity of the human eye. [3] [4] On the other hand, in terms of power per unit optical frequency, the Sun's peak emission is at 343 THz or a wavelength of 883 nm in the near infrared ...