EVM Calculation

The error vector magnitude represents theEuclidian distance between the ideal symbolcoordinate and the actual recorded symbol.
EVM is a way to measure and quantify the performance of a comunication system. A comlex signal sent by an ideal transmitter or received by a receiver would have all constellation points precisely at the ideal locations, however various imperfections in the implementation (such as carrier leakage, low image rejection ratio, phase noise etc.) cause the actual constellation points to deviate from the ideal locations. Informally, EVM is a measure of how far the points are from the ideal locations.

EVM calculation:
EVM ≈ 100%*Sphi(f)*π/180 ........Error vector magnitude due to phase noise.

Integrated Phase Noise

Integrated Phase Noise is a method of expressing the quality of the signal source. The IPN is calculated from the phase noise measurement.
Integrated results may be displayed in a number of formats:

Integrated single sideband phase noise [dBc]:

\int{L(f)}}df

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Spectral density of phase modulation, also kown as RMS phase error [degrees]:

Sphi(f) =(180/\pi)\sqrt(2\int{L(f)}df)\)  

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Spectral density of frequency fluctuations, also known as RMS frequency error or residual FM [Hz]:

Snu(f) =\sqrt(2\int{L(f)f^{2}}df)

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