RMS Error Vector Spectrum (802.16 OFDM)

The Error Vector Magnitude is the computed difference between IQ measured vector magnitude and IQ reference vector magnitude. The error vector magnitude is a complex value at each subcarrier for each OFDM Orthogonal Frequency Division Multiplexing: OFDM employs multiple overlapping radio frequency carriers, each operating at a carefully chosen frequency that is Orthogonal to the others, to produce a transmission scheme that supports higher bit rates due to parallel channel operation. OFDM is an alternative tranmission scheme to DSSS and FHSS. symbol. The RMS Error Vector Spectrum is the RMS average 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. for each subcarrier for all symbols within the burst. The "xRMS:__" display parameter (located at the top of the grid ) shows the number of symbols included in the RMS average EVM.

Averaging

Multiple-burst averaging is available for the RMS Error Vector Spectrum trace data. When averaging is turned on, the RMS Error Vector Spectrum trace contains data averaged over the number of bursts specified in the Count text box of the MeasSetup Properties Average tab dialog box (MeasSetup > Average). The "RMS:__" part of the "RMS:__ xRMS:__"display parameter shows the number of bursts included in the average.