The Spectrum Application
FPC1000
79
User Manual 1178.4130.02 ─ 02
3. Enter the reference level.
When you change the reference level while a trace is already displayed, the
R&S
FPC1000 adjusts the position of the trace.
The current reference level is indicated in the status bar. A blue dot in front of the
"Ref:" label indicates a
Defining a reference offset
The reference level offset is an arithmetic level offset. It shifts the measured levels by a
certain amount and changes the scale of the y-axis accordingly.
Such an offset is useful, for example, if you insert an external attenuator or amplifier
between DUT and RF input. The R&S
FPC1000 automatically takes the loss or gain
into account when the level is displayed - no manual calculations are necessary. A loss
introduced at the RF input must be entered as a positive number, a gain as a negative
number.
Note, however, that the internal reference level (used to adjust the hardware to the
expected signal) ignores the reference offset. Thus, it is important to keep in mind the
actual power level that the R&S
FPC1000 must handle. Do not rely on the displayed
reference level (internal reference level = displayed reference level - offset).
1. Press the "Ampt" key to open the amplitude menu.
2. Select the "Range / Ref Position" menu item to open the display range menu.
3. Select the "Reference Offset" menu item.
The R&S
FPC1000 opens an input field to define the reference offset.
4. Enter the required reference level offset.
The R&S
FPC1000 adjusts the position of the trace and scale of the y-axis as you
apply the changes.
A blue dot in front of the "Ref:" label in the status bar indicates that a level offset is
active.
Figure 9-6: Indicator of a reference level offset
Defining the position of the reference level
By default, the reference level the grid line at the top of the diagram represents the ref-
erence level. The current reference level position is indicated by a small grey triangle
on the y-axis.
Figure 9-7: Indicator of reference level position
Amplitude Configuration
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