The Spectrum Application
R&S
®
FPC
96
User Manual 1178.4130.02 ─ 07
14.3.2
Frequency Span
The span is the frequency range that the measurement covers. You can measure the
full frequency range of the R&S
FPC, or a smaller part of it. The span also defines
which frequency information is displayed in the measurement diagram - the span is the
frequency range around the
that you have defined.
The available span for frequency domain measurements depends on the instrument
model.
The span you should select depends on the bandwidth of the signal you are measuring
and the type of measurement that you perform. A rule of thumb is to select a span that
is at least twice as large as the bandwidth occupied by the measured signal.
You can define the span directly or in terms of a start and stop frequency.
Defining the frequency span
1. Press the "Freq" key to open the frequency menu.
2. Select the "Manual Span" menu item.
The R&S
FPC opens an input field to define the span.
Tip:
When you press the "Span" key, the R&S
FPC automatically opens an input
field to define the span. If the input field is inactive, you can open it with the "Man-
ual Span" menu item.
3. Enter a span.
The R&S
FPC adjusts the span of the horizontal axis to the value you have
entered.
Tip:
If you define a span of 0
Hz (zero span), the R&S
FPC measures in the time
domain.
In that state, the R&S
FPC measures the signal at the current center frequency
only. Instead of displaying the spectrum, the R&S
FPC shows the signal power
over a certain time period (like an oscilloscope). The horizontal axis becomes the
time axis. The display always starts at 0
s and stops after the current sweep time.
You can select time domain measurements without having to enter the value man-
ually. Instead, select the "Zero Span" menu item to get a span of 0
Hz.
Full span measurements
You can restore the span that covers the complete frequency range supported by the
R&S
FPC quickly and without having to enter the value manually with the "Full Span"
menu item.
If you need to switch back to a smaller span, you can restore the span that was last
selected with the "Last Span" menu item.
Frequency Configuration
