The Spectrum Application
R&S
®
FPC
77
User Manual 1178.4130.02 ─ 07
Defining the reference level
is the power level that the R&S
FPC expects at the RF input. When
you select the reference level, make sure that you do not overload the R&S
FPC by
applying a signal whose power exceeds the maximum reference level.
As the power is measured with a small
bandwidth, it is still possible to overload the R&S
FPC, even if the trace is within the
measurement diagram. To prevent an overload, measure the occupied bandwidth with
the largest resolution bandwidth possible using the peak detector. If you set these
parameters, it is not possible for the trace to exceed the reference level.
To simplify operation and to prevent incorrect measurements, the R&S
FPC has an
automatic routine for setting the reference level.
1. Press the "Meas" key to open the measurement menu.
2. Select the "Level Adjust" menu item.
The R&S
FPC performs a measurement to determine the optimal reference level.
It uses a resolution bandwidth of 1
MHz, a video bandwidth of 1
MHz and the peak
detector. After finishing the automatic measurement, the R&S
FPC sets the optimal
reference level.
Defining the burst length
The burst length or measurement time defines the expected length of the burst. The
measurement time is the time period over which the signal power is measured.
The minimum burst time is the time corresponding to one trace pixel. The maximum
burst time corresponds to the current sweep time (with the sweep time being the com-
plete time displayed on the x-axis).
The burst time must be equal or less than the sweep time. If you define a burst time
that is longer than the sweep time, the R&S
FPC selects a burst equal to the current
sweep time. To measure a longer burst, you have to increase the sweep time first.
1. Press the "Meas" key to open the measurement menu.
2. Select the "Burst Length" menu item.
The R&S
FPC opens an input field to define the burst length.
3. Enter the expected length of the burst.
The R&S
FPC analyzes the power of the burst. The current burst length is indica-
ted by two blue vertical lines in the diagram (the first line indicating the beginning of
the burst is usually at the origin of the x-axis).
Using a trigger
is the best method to measure bursts, as it keeps the display of the
burst stable. You can use either the video trigger or an external trigger (if the DUT has
some sort of trigger equipment). The functionality of both trigger sources is similar to
the functionality in the spectrum application.
1. Connect the DUT trigger output to the R&S
FPC trigger input.
Measurements and Result Displays
