Instrument Function
R&S
®
SMU200A
335Operating Manual 1007.9845.32 ─ 15
In case of standards in which it is possible to switch between different modulation
modes, the signal is output only and cannot be supplied from an external source. In
such cases it indicates the modulation mode internally (standard GSM: signal high
(1) = modulation mode GMSK and signal low (0) = modulation mode 8PSK EDGE).
The CW control signal is generated internally and fed to the AUX I/O interface. The control
signals for power ramping can be provided externally for Custom Digital Modulation only.
When generated internally the signals are output on the AUX I/O interface.
A dedicated internal "Control Data Editor" is provided for defining the control signals. This
editor with its intuitive graphical interface can be used to define and save control signals.
Definition by generating or editing a binary list is no longer necessary (though it is still
possible via the IEC bus).
A separate file with the file extension *.dm_iqc is created for each defined control signal
and held on the R&S Signal Generator hard disk.
If the "Component Data Editor" is used, the "Control Data Editor" is integrated with it. The
defined control data is not held separately, but stored with the data structure. This applies
both to signals of the Data Editor Realtime and the Data Editor Offline.
Power Ramping and Level Attenuation
In TDMA radio networks it is necessary to control the RF output signal envelope syn-
chronously for the purpose of digital modulation. The signals "Burst" Gate and "Lev Att"
are used for this. These signals are internally generated.
In case of "Custom Digital Modulation", they can also be supplied from an external source
via the AUX I/O interface.
When power ramping is enabled, a ramp is generated whenever there is a data switch
on the "Burst" signal (from high to low or low to high). The steepness of this ramp can be
adjusted. Power ramping is enabled and configured in the "Power Ramp Control" sub-
menu.
The "Lev_Att" signal is used to control a defined level attenuation. If level attenuation is
enabled, the modulation signal level is attenuated by a defined value if the "Lev_Att"
signal is high. The level attenuation value is defined in the "Power Ramp Control" menu.
For the "GSM/EDGE" standard a maximum of 7 different level attenuation values can be
defined and allocated separately to the 8 slots quite independently of one another. Level
attenuation is enabled either in the "Power Ramp Control" menu (Custom Digital Modu-
lation) or in the "Burst Editor" (GSM/EDGE).
Level attenuation enables to simulate radio stations located at various distances.
The diagram below shows an example of how the power ramping signals work.
Baseband Signal - Baseband Block
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