EVM Normalization Reference (Digital Demod)

EVM Normalization Reference sets the normalization value for certain error summary metrics. EVM Normalization Reference also affects the normalization value used for traces when Normalize IQ Traces is selected. Note that the normalization value used for traces differs from the normalization value used for error summary metrics when EVM Normalization Reference is set to Reference RMS.

These Syms/Errs summary table metrics are normalized by the EVM Normalization Reference:

EVM
Mag Err

There are two possible values for EVM Normalization Reference:

Constellation Maximum (default): sets the normalization value to the maximum constellation magnitude.

For example, the normalization value would be the level of the corner point in a 16QAM constellation or the outermost ring for APSK formats. For "cross-QAM Quadrature Amplitude Modulation" constellations (32QAM, 128QAM, 512QAM, 2048QAM), the normalization value would be set to the magnitude of the outer corners of a square that encompasses the constellation, even though the constellation itself does not really use the outer corners.
Reference RMS: sets the normalization value to the RMS level of the IQ Reference symbol points.

If the only impairment in the input signal is Additive White Gaussian Noise, using Reference RMS will make the averaged EVM approach the inverse of the Signal-to-Noise ratio of the signal. Using Reference RMS also makes it easier to compare EVM Error vector magnitude (EVM): A quality metric in digital communication systems. See the EVM metric in the Error Summary Table topic in each demodulator for more information on how EVM is calculated for that modulation format. values between signals of different modulation formats.

Reference RMS is only available for I/Q modulation formats with more than one constellation magnitude level (16QAM, Star 32QAM, 32APSK, etc.).