Rohde & Schwarz FSQ series, Quick Start Manual

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Quick Start Guide 1313.9652.62 - 02 5.5
R&S FSQ Basic Measurement Examples
Measuring a Sinusoidal Signal
Reduce the frequency span (SPAN) to 10 kHz
➢
Press the SPAN key.
➢
Using the numeric keypad, enter 10 in the entry field and confirm the entry with the kHz
key.
The generator signal is measured using a span of 10 kHz. The measurement point
resolution of the trace is now approx. 16 Hz (10 kHz span /625 measurement points), i.e.
the precision of the marker frequency display increases to approx. ±8 Hz.
5.1.1.3 Setting the Reference Level
With analyzers, the reference level ( REF LEVEL ) is the level at the upper limit of the diagram.
To achieve the widest dynamic range possible for a spectrum measurement, use the entire
level span of the analyzer. In other words, the highest level that occurs in the spectrum must
be located at the top edge of the diagram (=reference level) or immediately below it.
In the preset setting, the value of the reference level is -20 dBm. If the input signal is -30 dBm,
the reference level can be reduced by 20 dB without causing the signal path to be overloaded.
1. Reduce the reference level by 10 dB.
➢
Press the AMPT key.
The AMPT menu will appear in the softkey bar. The REF LEVEL softkey will be
highlighted in red to indicate that it is activated for data entry. The entry field for the
reference level is also opened and displays a value of -20 dBm.
➢
Using the numeric keypad, enter 30 and confirm the entry with the -dBm key.
The reference level is now set to -30 dBm. The maximum of the trace is near the
maximum of the measurement diagram. However, the increase in the displayed noise is
not substantial. Thus, the distance between the signal maximum and the noise display
(=dynamic range) has increased.
2. Setting the marker level equal to the reference level
The marker can also be used 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:
➢
Press the MKR
−>
key.
➢
Press the REF LVL = MKR LVL softkey.
The reference level will be set equal to the measured level where the marker is located.
Thus, setting the reference level is reduced to two keystrokes.
If the reference level that is selected is less than the highest signal that
occurs in the spectrum, the signal path in the R&S FSQ will be
overloaded.
In this case, the message
IFOVL will appear on the left-hand edge of
the diagram.