LTE Multi Evaluation Measurement
R&S
®
CMW-KM5xx/-KS5xx
497
User Manual 1173.9628.02 ─ 16
Whenever the combined signal path scenario is activated or the controlling application
is changed, the frame trigger signal provided by the controlling signaling application is
selected automatically as trigger source.
3.2.1.6
Trigger Modes
The LTE "Multi Evaluation" measurement can be performed in the following trigger
modes:
●
Free Run (Fast Sync): The measurement starts immediately after it is initiated. The
R&S
CMW decodes the signal to derive its slot and frame timing so that the "Mea-
surement Length" can start at a slot or subframe boundary of the UL LTE signal.
This trigger mode should only be used for uplink signals using all subframes for
transmission.
●
Free Run (No Sync): The measurement starts immediately after it is initiated, with-
out any synchronization.
This trigger mode is faster than the "Free Run (Fast Sync)" mode. It can be used
for power monitor, ACLR and emission mask measurements, provided that the
resource block allocation and uplink power are continuous. All other results must
be ignored (e.g. modulation results, RB allocation and power dynamics).
●
IF Power: With an internal IF power trigger, the measurement is triggered by the
power ramp of the received bursts.
●
External Trigger A/B: External trigger signal fed in via TRIG A or TRIG B on the
rear panel of the instrument.
●
Additional trigger modes: Other firmware applications, e.g. the LTE signaling appli-
cation (option R&S CMW-KS500/-KS550) or the GPRF generator may provide
additional trigger modes. Refer to the documentation of the corresponding firmware
application for a description of these trigger modes.
chapter 3.3.6, "Trigger Settings"
3.2.1.7
Calculation of Modulation Results
Modulation results are based on a comparison between the measured signal, correc-
ted by the average frequency and timing offset for each measured subframe, and an
ideal reference waveform.
See also: "Modulation Accuracy" in the R&S
CMW user manual, chapter "System
Overview"
3GPP TS 36.101, Annex F, specifies the following additional conditions:
●
The I/Q origin offset shall be removed from the evaluated signal before calculating
the EVM and the inband emissions.
●
The EVM calculation shall be based on two different FFT processing windows in
time domain, separated by the "EVM window length" W. The minimum test require-
ment applies to the larger of the two obtained EVM values.
The definition of the EVM window and the two FFT processing windows is shown
below.
General Description
深圳德标仪器
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