Keysight E6680A - Page 196

3 IQ Analyzer (Basic) Mode
3.1 Complex Spectrum Measurement
Start/Stop annotation mode, Start Freq and Stop Freq are displayed below the
graticule instead of Center Frequency and Span.
Pressing Center Frequency also sets the frequency entry mode to Center/Span. In
Center/Span mode, the center frequency and span values are displayed below the
graticule, and the default active function in the Frequency menu is Center
Frequency.
When Display Scale Type is set to LOG, pressing Center Frequency sets the
frequency that corresponds to the arithmetic mean of the start frequency and stop
frequency, which is not at the horizontal center of the graticule.
The center frequency setting is the same for all measurements within a Mode, that
is, it is Meas Global. Some Modes are also able to share a Mode Global center
frequency value. If this is the case, the Mode has a Global tab in its Meas Setup
menu.
Center Frequency sets (and queries) the center frequency for the currently selected
input. If your instrument has multiple inputs, and you select another input, Center
Frequency changes to the value for that input. SCPI commands are available to
directly set Center Frequency for a specific input (see "RF Center Frequency" on
page 199 and "Ext Mix Center Freq" on page 200).
Center Frequency is remembered as you go from input to input. Thus you can set a
Center Frequency of 10GHz with the RF Input selected, change to BBIQ and set a
Center Frequency of 20MHz, then switch to External Mixing and set a Center
Frequency of 60GHz. When you return to the RF Input, Center Frequency reverts to
10GHz; back to BBIQ and it is 20MHz; back to External Mixing and it is 60GHz.
Remote Command
[:SENSe]:FREQuency:CENTer <freq>
[:SENSe]:FREQuency:CENTer?
Example Set Center Frequency to 50MHz:
:FREQ:CENT 50 MHz
Increment Center Frequency by the value of CF Step:
:FREQ:CENT UP
Return the current value of Center Frequency:
:FREQ:CENT?
Notes Sets the RF, External Mixing or I/Q Center Frequency depending on the selected input:
–
For RF input it is equivalent to :FREQ:RF:CENT
–
For I/Q input it is equivalent to :FREQ:IQ:CENT
–
For External Mixer it is equivalent to :FREQ:EMIX:CENT
Preset and Max values depend on Hardware Options
If no terminator (for example, MHz) is sent, the terminator Hz is used. If a terminator with unit other
than frequency is used, an invalid suffix error message is generated
IQ Analyzer Mode User's &Programmer's Reference 196