Keysight E6680A - Complex Spectrum Measurement

3 IQ Analyzer (Basic) Mode
3.1 Complex Spectrum Measurement
3.1 Complex Spectrum Measurement
The Complex Spectrum measurement provides wideband FFT-based spectrum
analysis capability for the instrument. The control of the measurement was designed
to be familiar to those who are accustomed to using swept spectrum analyzers.
The measurement uses digital signal processing to sample the input signal and
convert it to the frequency domain. With the instrument tuned to a fixed center
frequency, samples are digitized at a high rate, converted to I and Q components
with DSP hardware, and then converted to the frequency domain with FFT software.
This measurement is FFT (Fast Fourier Transform) based. The FFT-specific
parameters are located in the advanced menu. Also available under basic mode
spectrum measurements is an I/Q window, which shows the I and Q signal
waveforms in parameters of voltage versus time. The advantage of having an I/Q
view available while in the spectrum measurement is that it allows you to view
complex components of the same signal without changing settings or
measurements.
Measurement Commands
The general functionality of "CONFigure" on page 1076, "INITiate" on page 1077,
"FETCh" on page 1077, "MEASure" on page 1079, and "READ" on page 1078 are
described in the section SCPI Operation and Results Query in the topic
Programming the Instrument.
The following measurement commands and queries are used to configure the
measurement:
:INITiate:SPECtrum
Initiates a trigger cycle for the SPECtrum
measurement, but does not return any data. You must
then use :FETC:SPEC[n]? to retrieve data
Does not change any measurement settings
:CONFigure?
Returns the long form name of current measurement, in
this case, SPECtrum
:CONFigure:SPECtrum
Selects SPECtrum measurement with Meas Setup
settings in preset state – same as "Meas Preset" on
page 233
:CONFigure:SPECtrum:NDEFault
Selects SPECtrum measurement without affecting
settings
The following queries are used to retrieve the results:
:FETCh:SPECtrum?
Retrieves the data specified by n
:MEASure:SPECtrum
Switches to SPECtrum measurement, restores default values, starts
143 IQ Analyzer Mode User's &Programmer's Reference