RF: Connection Control CMU
1100.4903.12 4.60 E-10
The value range depends on the selected RF input (see section Generator Settings
(Connection Control – Generator) on page 4.61):
External attenua-
tion
If an external input attenuation is reported to the instrument (see section RF Con-
nectors (Connection Control – RF) on page 4.65), all levels measured are refer-
enced to the output of the DUT and therefore shifted with respect to the actual level
at the input connectors of the CMU. The level ranges for the input connectors are
shifted as well.
Input levels exceeding the RF Max. Level can not be measured; the corresponding
measurement result fields indicate invalid results “– – –“.
Error messages If the value determined for RF Max. Level is too high or too low, a window with the
error message "<Max_Level> is out of range. <permissible max. value> is limit."
and three fields will appear:
Accept The permissible max. value is accepted as RF Max. Level
Re-edit RF Max. Level is entered once again
Cancel The last valid input value is maintained
When switching over to another input, the current value of RF Max. Level is auto-
matically adapted, if required:
• Towards lower values to the maximum permissible value of the new input,
• Towards upper values to the minimum value of the new input.
Note: A maximum input level can be entered even if automatic level setting
(autoranging) is selected. The entered level is used as a start value for
the autoranging routine and is also important to ensure safe switch-
over to manual setting.
Remote control
[SENSe:]LEVel:MAXimum <Level>
RF Attenuation
RF Attenuationdefines how the RF analyzer of the CMU is tuned to meet the re-
quirements of the current measurement type. In general, a compromise between
the acceptable noise level in the displayed result and the contribution of internally
generated distortion must be reached.
Normal Mixer level in normal range
Low noise Mixer level enhanced by +10 dB (full dynamic range of CMU,
therefore recommended for both Power and Spectrum meas-
urements)
Low distortion Mixer level reduced by –10 dB (high intermodulation spacing)
The RF Attenuation setting permits the CMU to be adapted to the requirements of
the measurement. The advantages and disadvantages of the settings Low noise
and Low distortion are listed in the following table.
Advantages Disadvantages
Low noise
Low noise
high dynamic range
No RF overdrive reserve
Risk of intermodulation
Low distortion
High intermodulation spacing Lower dynamic range
Remote control
[SENSe:]LEVel:ATTenuation NORMal | LNOise | LDIStortion
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