![Rohde & Schwarz FSH13 Operating Manual Download Page 109](http://html.mh-extra.com/html/rohde-and-schwarz/fsh13/fsh13_operating-manual_1477832109.webp)
R&S FSH
Spectrum Analyzer Mode
Configuring Spectrum Measurements
Operating Manual 1173.6275.12 - 30
94
3.2 Configuring Spectrum Measurements
3.2.1 Configuring the Horizontal Axis
The FREQ key contains all necessary functions to configure the horizontal axis for
spectrum measurements.
The contents of the menu depend on the currently selected measurement.
Usually, the horizontal axis contains frequency information in spectrum mode. You can
specify the frequency in terms of the center frequency or by defining a start and stop
frequency for a particular span.
If you know the frequency of the signal you are measuring, it is best to match the
center frequency to the signal's frequency. If you are investigating signals, e.g.
harmonics, that are within a particular frequency range, the best option is to enter a
start and stop frequency to define the span.
3.2.1.1 Defining the Center Frequency
The center frequency represents the frequency at the center of the horizontal axis in
the diagram area.
► Press the FREQ key.
The R&S FSH opens the frequency menu.
When you press the FREQ key, the R&S FSH automatically opens an input field to
define the center frequency. If the input field is inactive, you can open it with the
"Center Freq" softkey.
► Enter the center frequency you need.
The frequency you have entered becomes the new center frequency.
While adjusting the center frequency, you may obtain a value that is outside the
R&S FSH maximum span. If this happens, the R&S FSH automatically reduces the
span.
3.2.1.2 Defining a Frequency Step Size
If you set the center frequency with the rotary knob or the cursor keys, the distance of
each step that you take depends on the span. With the rotary knob, the smallest
possible step is a pixel. As the trace consists of 631 pixels, each step is equal to 1/630
of the span. With the cursor keys, the step is 10% of the span or one division of the
grid.
You can set another step size.
► Press the FREQ key.
► Press the "CF Step Size" softkey.
The R&S FSH opens a submenu that contains possible step sizes.