R&S FSL Using Markers and Delta Markers – MKR Key
1300.2519.12 4.57 E-11
The following settings have to be made to ensure that the power density measurement yields correct
v
alues:
• Detector: Sample or RMS
• Video bandwidth
:
0.1 resolution bandwidth with sample detector
3 x resolution bandwidth with RMS detector
• Trace averaging:
With the sample detector, the trace can additionally be set to average to stabilize the measured
values. With RMS detector used, trace averaging must not be used since in this case it produces
too low noise levels which cannot be corrected. Instead, the sweep time can be increased to obtain
stable measurement results.
The R&S FSL uses the following correction factors to evaluate the noise density from the marker level:
• Since the noise power is indicated with reference to 1 Hz bandwidth, the bandwidth correction value
is deducted from the marker level. It is 10 x lg (1 Hz/BWNoise), where BWNoise is the noise or
power bandwidth of the set resolution filter (RBW).
• RMS detector: With the exception of bandwidth correction, no further corrections are required since
this detector already indicates the power with every point of the trace.
• Sample detector: As a result of video filter averaging and trace averaging, 1.05 dB is added to the
marker level. This is the difference between the average value and the RMS value of white noise.
With a logarithmic level axis, 1.45 dB is added additionally. Logarithmic averaging is thus fully taken
into account which yields a value that is 1.45 dB lower than that of linear averaging.
• To allow a more stable noise display the adjacent (symmetric to the measurement frequency) points
of the trace are averaged.
• For span > 0, the measured values are averaged versus time (after a sweep).
Note: The R&S FSL noise figure can be calculated from the measured power density level. It is
calculated by deducting the set RF attenuation (RF Att) from the displayed noise level and
adding 174 to the result.
Softkeys of the marker menu
The following table shows all softkeys available in the marker menu. It is possible that your instrument
configuration does not provide all softkeys. If a softkey is only available with a special option, model or
(measurement) mode, this information is delivered in the corresponding softkey description.
If the Spectrogram Measurement option (K14) is activated, the edit dialog box for markers and delta
markers is extended. For details refer to "Markers and marker values" on page 4.193.
Menu / Command Submenu / Command Command
Marker 1
Marker 2
Marker Norm/Delta
Noise Meas On/Off
Phase Noise/Ref Fixed Phase Noise On/Off
Ref Point Level
Ref Point Frequency/
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