3 VMA Mode
3.4 IQ Waveform Measurement
Notes This command is the same in all Modes, but the parameter is Measurement Global. So, the value is
independent in each Mode and common across all the measurements in the Mode
Couplings When returning to External Mixing after having been switched to one of the other inputs (for example,
RF), you return to the settings that existed when you left External Mixing. So, you return to the band you
were in, with the Center Frequency that you had. However, Span is not an input-dependent parameter,
therefore the Span setting from the other input is retained. Thus, the instrument returns to the Span
setting from the previous input, limited as necessary by the current mixer setup
Preset When a Mode Preset is performed while in External Mixing, the Start frequency of the current Mode is
set to the nominal Min Freq of the lowest harmonic range in the Harmonic Table for the current mixer
setup. Similarly, the Stop frequency of the current Mode is set to the nominal Max Freq of the highest
harmonic range in the Harmonic Table. Center Frequency thus presets to the point arithmetically
equidistant from these two frequencies
Note that, if the current measurement has a limited Span available to it, and cannot achieve the span
shown in the table (Span = Stop Freq – Start Freq), the instrument uses the maximum Span the
measurement allows, and still sets Center Frequency to the midpoint of the Start and Stop Freq values
in the Harmonic Table
When Restore Input/Output Defaults is performed, the mixer presets to the 11970A, whose Start and
Stop frequencies are 26.5 and 40 GHz respectively. The center of these two frequencies is 33.25 GHz
Therefore, after Restore Input/Output Defaults, if you go into External Mixing and do a Mode Preset
while in the Spectrum Analyzer Mode, the resulting Center Frequency is 33.25 GHz
State Saved Yes
Min The minimum frequency in the currently selected mixer band +5 Hz
Max The maximum frequency in the currently selected mixer band –5 Hz
I/Q Center Freq (Remote Command Only)
Specifies the I/Q Center Frequency. Sets the Center Frequency to be used when the
I/Q input is selected, even if the I/Q input is not the input that is selected at the time
the command is sent. Note that the Center Frequency function in the Frequency
menu on the front panel always applies to the currently selected input.
Remote
Command
[:SENSe]:FREQuency:IQ:CENTer <freq>
[:SENSe]:FREQuency:IQ:CENTer?
Example
:FREQ:IQ:CENT: 30 MHz
Notes This command is the same in all Modes, but the parameter is Measurement Global. So, the value is
independent in each Mode and common across all the measurements in the Mode
Preset 0 Hz
State Saved Saved in instrument state
Min/Max –/+40.049995 MHz
743 Vector Modulation Analyzer Mode User's &Programmer's Reference
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