Service manual

WLAN TX Measurements
R&S
®
FSV-K91/91n/91ac/91p
49Operating Manual 1176.7649.02 ─ 04
Burst EVM (Direct)
Burst EVM (Direct) evaluates the root mean square EVM over one burst. That is the
square root of the averaged error power normalized by the averaged reference power:
Before calculation of the EVM, the measurement signal is corrected in respect of fre-
quency error, clock deviation and IQ impairments.
If more than one burst is evaluated (several analyzed bursts in the capture buffer or
with the help of Overall Burst Count), the Min / Mean / Max columns show the mini-
mum, mean or maximum Burst EVM of all analyzed bursts.
Burst EVM is not part of the IEEE standard and no limit check is specified. Neverthe-
less, this commonly used EVM calculation can give some insight in modulation quality
and allows comparisons to other modulation standards.
Fig. 3-10: IQ diagram for EVM calculation
Measurement Result Types