RMS Error Vector Time (LTE)
shows the Root Mean Square (RMS) average EVM for each symbol. The RMS average for each symbol is calculated from the subcarrier EVMs of currently selected channels and signals (see Composite Include).
The value "ss" in the "xRMS: ss" or "xPeak: ss" annotation at the top of the trace is how many subcarriers were included in the current measurement. Only symbols containing channels/signals selected in Composite Include are included in the count.
MBMS mixed-mode CP
MBMS signals are transmitted during the MBSFN region of MBSFN subframes using Extended CP mode (6 symbols per slot). The non-MBSFN region of these subframes (and the rest of the frame) can be transmitted in Normal or Extended CP mode.
For mixed-CP-mode LTE frames, traces that show time on the x-axis in units of syms (OFDM symbols) would need unevenly spaced x-axis points to correctly represent the time locations of the symbols (since extended CP symbols are longer than normal CP symbols).
Instead of using non-uniform x-axis spacing of symbol points, the LTE demodulator shows the time axis as if all the slots used Normal CP (with 7 symbols per slot), and for MBSFN slots, the demodulator fills the first 6 symbols of the slot with the extended CP symbols, leaving the 7th symbol blank.
See Also
