The Spectrum Application (RF Measurements)
R&S
®
FPL1000
237
User Manual 1178.3370.02 ─ 03
In the presettings, the value of the reference level is 0
dBm. If the input signal is
-30
dBm, the reference level can be reduced by 30
dB without causing the signal path
to be overloaded.
Reducing the reference level by 30 dB
► Set the reference level to
-30
dBm
.
The maximum of the trace is near the maximum of the measurement diagram. The
increase in the displayed noise is not substantial. Thus, the distance between the
signal maximum and the noise display (=dynamic range) has increased.
Setting the reference level with the help of a marker
You can also use a marker to shift the maximum value of the trace directly to the top
edge of the diagram. If the marker is located at the maximum level of the trace (as in
this example), the reference level can be moved to the marker level as follows:
1. Press the MKR -> key.
2. Select "Ref Lvl = Mkr Lvl" .
The reference level is set to the current marker level.
Measuring the Signal Frequency Using the Signal Counter
The built-in signal counter allows you to measure the frequency more accurately than
measuring it with the marker. The frequency sweep is stopped at the marker, and the
R&S
FPL1000 measures the frequency of the signal at the marker position (see also
Chapter 7.9.4.1, "Precise Frequency (Signal Count) Marker"
In the following example, the frequency of the generator at 128
MHz is shown using
the marker.
Prerequisite
Precise frequency measurements require a precise reference frequency. Therefore, an
external reference frequency from the signal generator is used. Connect the signal
generator's REF OUT connector to the analyzer's REF IN connector.
1. Select PRESET to reset the instrument.
2. Set the center frequency to
128
MHz
.
3. Set the frequency span to
1
MHz
.
4. Select "Setup" > "Reference" > "External Reference 10 MHz" to activate the exter-
nal reference frequency.
5. Select MKR to activate marker 1 and automatically set it to the maximum of the
trace.
The level and the frequency of the marker are displayed in the marker results in the
diagram or the marker table.
6. Select MKR FUNC > "Signal Count" to activate the signal counter.
Measurements and Results
