LTE SRS Measurement
R&S
®
CMW-KM5xx/-KS5xx
826
User Manual 1173.9628.02 ─ 16
Expected Nominal Power
Defines the nominal power of the RF signal to be measured. An appropriate value for
LTE signals is the peak output power at the DUT during the measurement. The "Ref.
Level" is calculated as follows:
Reference power = Expected Nominal Power + User Margin
Note:
The actual input power at the connectors (i.e. the "Reference Level" minus the
"External Attenuation (Input)" value, if all power settings are configured correctly) must
be within the level range of the selected RF input connector; refer to the data sheet.
In the Standalone (SA) scenario, this parameter is controlled by the measurement. In
the Combined Signal Path (CSP) scenario, it is controlled by the signaling application.
Remote command:
(SA)
(CSP)
(CSP)
User Margin
Margin that the R&S
CMW adds to the "Expected Nominal Power" in order to deter-
mine its reference power ("Ref. Level"). The "User Margin" is typically used to account
for the known variations of the RF input signal power, e.g. the variations due to a spe-
cific channel configuration.
The variations (crest factor) depend on the LTE signal parameters, in particular the
modulation scheme. If the "Expected Nominal Power" is set to the peak power during
the measurement, a 0 dB user margin is sufficient.
In the Standalone (SA) scenario, this parameter is controlled by the measurement. In
the Combined Signal Path (CSP) scenario, it is controlled by the signaling application.
Remote command:
(SA)
(CSP)
Mixer Level Offset
Varies the input level of the mixer in the analyzer path. A negative offset reduces the
mixer input level, a positive offset increases it. Optimize the mixer input level according
to the properties of the measured signal.
Mixer Level
Offset
Advantages
Possible Shortcomings
< 0 dB
Suppression of distortion (e.g. of the inter-
modulation products generated in the
mixer)
Lower dynamic range (due to smaller sig-
nal-to-noise ratio)
> 0 dB
High signal-to-noise ratio, higher dynamic
range
Risk of intermodulation, smaller overdrive
reserve
In the Standalone (SA) scenario, this parameter is controlled by the measurement. In
the Combined Signal Path (CSP) scenario, it is controlled by the signaling application.
Remote command:
(SA)
(CSP)
GUI Reference
深圳德标仪器
135-1095-0799
