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Common Measurement Functions
FREQ Channel
I/Q Center Freq
SCPI command for specifying the I/Q Center Frequency. This command will set the Center Frequency to
be used when the I/Q input is selected, even if the I/Q input is not the input which is selected at the time
the command is sent. Note that the
Center Freq function in the Frequency menu on the front panel
always applies to the currently selected input.
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. The Center Freq thus presets
to the point arithmetically equidistant from these two frequencies.
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
analyzer uses the maximum Span the measurement allows, and still sets the
Center Freq 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 a Restore Input/Output Defaults, if you go into External
Mixing and do a Mode Preset while in the Spectrum Analyzer Mode, the
resulting Center Freq is 33.25 GHz.
State Saved: Saved in instrument state.
Min: The minimum frequency in the currently selected mixer band + 5 Hz
Max: The maximum frequency in the currently selected mixer band – 5 Hz
If the knob or step keys are being used, also depends on the value of the other
three interdependent parameters Span, Start Frequency and Stop Frequency
Initial S/W Revision: A.08.01
Scope: Meas Global
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: –40.049995 MHz