RMS Error Vector Spectrum (Pre-5G)

Trace > Data > Stream (x) > Ch(x) > RMS Error Vector Spectrum

where X is the selected channel

RMS Error Vector Spectrum is a plot of the Root Mean Square (RMS) average of multiple "RMS subcarrier EVM" data results. Use this trace to obtain an average of the "RMS subcarrier 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 across multiple bursts or measurements. Each measurement produces one set of "RMS subcarrier EVM" data results. The "RMS Error Vector Spectrum" trace is the same as averaging multiple Error Vector Spectrum trace measurements, one Error Vector Spectrum measurement is made per average count. You specify the number of measurements "average count" included in the RMS average calculation using the Average Count parameter (MeasSetup > Average tab > count).

Trace Annotation	Description
RMS: n	Indicates that "n" number of measurements (bursts) are included in computing the RMS averaged "RMS subcarrier EVM" result.
xRMS: n	Indicates that "n" number of 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. symbols are included in each "RMS subcarrier EVM" measurement result (Error Vector Spectrum trace).

Trace Annotation

Description

RMS: n

Indicates that "n" number of measurements (bursts) are included in computing the RMS averaged "RMS subcarrier EVM" result.

xRMS: n

Indicates that "n" number of 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. symbols are included in each "RMS subcarrier EVM" measurement result (Error Vector Spectrum trace).

When the measurement average count is equal to 1, the "RMS Error Vector Spectrum" trace data results are identical to the Error Vector Spectrum trace "RMS subcarrier EVM" data results.

Trace Color coding Scheme

A multi-color coding scheme is used to make it easy to visually identify common symbols, subcarriers, and data results within various OFDM Traces. This makes cross trace data comparisons and analysis easy to accomplish. Different colors are assigned to symbols representing a common subcarrier type including: Preamble, Pilot, Data, and Null subcarrier types. Some common color scheme Traces include: Error Vector Spectrum, Error Vector Time, and IQ Meas trace data.

You can also customize and re-assign Trace colors schemes, see the Display Preferences Color tab (click Utilities > Display Preferences > Color tab and select a new color for the active Mod Type element).