3 Spectrum Analyzer Mode
3.2 Swept SA Measurement
3.2 Swept SA Measurement
The Swept SA measurement lets you perform “traditional” Spectrum Analysis, that
is, Swept and Zero Span measurements, as well as “Swept FFT” analysis (FFT
analysis presented as though it were swept).
Swept Spectrum Analysis (Freq Domain)
The instrument sweeps the LO to generate a heterodyned IF signal that can be
detected to analyze the signal content of a range of frequencies. The x-axis of the
display is frequency, the Y Axis is amplitude.
Swept FFT Analysis (Freq Domain)
In some cases, there is an advantage to not actually sweeping the LO, but instead
analyzing the signal by taking a time record and performing FFT analysis. This is
what is done in swept FFT analysis, but the data is still presented as though it were a
sweeping spectrum analyzer. The x-axis of the display is frequency, the Y Axis is
amplitude.
Zero Span Analysis (Time Domain)
In Zero Span analysis, the instrument stops sweeping the LO, placing it at the center
frequency, and then takes time data from the detector while stopped at that
frequency. Because the LO is not moving, the frequency span is zero. The time data
is presented left to right across the screen just like on an oscilloscope. The x-axis of
the display is time, and the Y Axis is amplitude.
All of the tools such as markers, peak tables, limit lines, trace math, N dB points, and
marker functions are available in Zero Span measurement analysis, although some
work differently in the time and frequency domains. See the Span control
description under the Freq front panel key for detail on the user interface differences
between Swept analysis and Zero Span analysis.
Swept SA Measurement Commands
The general functionality of "CONFigure" on page 2753, "INITiate" on page 2754,
"FETCh" on page 2754, "MEASure" on page 2756, and "READ" on page 2755 are
described in the section SCPI Operation and Results Query in the topic
Programming the Instrument.
184 Spectrum Analyzer Mode User's &Programmer's Reference
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