Test Setup R&S FSL
1300.2519.12 2.2 E-11
Test Setup
All of the following examples are based on the standard settings of the R&S FSL. These are set with the
PRESET key. A complete listing of the standard settings can be found in chapter "Instrument
Functions", section "Initializing the Configuration – PRESET Key".
In the following examples, a signal generator is used as a signal source. The RF output of the signal
generator is connected to the RF input of R&S FSL.
If a 65 MHz signal is required for the test setup, as an alternative to the signal generator, the internal 65
MHz reference generator can be used:
1. Switch on the internal reference generator.
Press the SETUP key.
Press the Service softkey.
Press the Input RF/Cal/TG softkey, until Cal is highlighted.
The internal 65 MHz reference generator is now on. The R&S FSL's RF input is switched off.
2. Switch on the RF input again for normal operation of the R&S FSL. Two ways are possible:
Press the PRESET key
Press the SETUP key.
Press the Service softkey.
Press the Input RF/Cal/TG softkey, until RF is highlighted.
The internal signal path of the R&S FSL is switched back to the RF input in order to resume
normal operation.
Measurement of Harmonics
Measuring the harmonics of a signal is a frequent problem which can be solved best by means of a
spectrum analyzer. In general, every signal contains harmonics which are larger than others.
Harmonics are particularly critical regarding high–power transmitters such as transceivers because
large harmonics can interfere with other radio services.
Harmonics are generated by nonlinear characteristics. They can often be reduced by lowpass filters.
Since the spectrum analyzer has a nonlinear characteristic, e.g. in its first mixer, measures must be
taken to ensure that harmonics produced in the spectrum analyzer do not cause spurious results. If
necessary, the fundamental wave must be selectively attenuated with respect to the other harmonics
with a highpass filter.
When harmonics are being measured, the obtainable dynamic range depends on the second harmonic
intercept of the spectrum analyzer. The second harmonic intercept is the virtual input level at the RF
input mixer at which the level of the 2nd harmonic becomes equal to the level of the fundamental wave.
In practice, however, applying a level of this magnitude would damage the mixer. Nevertheless the
available dynamic range for measuring the harmonic distance of a DUT can be calculated relatively
easily using the second harmonic intercept.
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