R&S
FS-K30
Measurements & Settings
Frequency
Settings
Software Manual 1300.6637.42 - 03
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The value entered is applied across the complete frequency range. The default value
of 999.99 dB means that the second sideband does not noticeably affect the
measurement result because a suppression of 999.99 dB is applied to it. This
corresponds to the generally used single-sideband (SSB) measurement. An entry
of 0 dB would mean that both sidebands are converted to the same extent – this
corresponds to a double-sideband (DSB) measurement.
Thus, for a SSB mixer,
Image Rejection
should be set to 999.99 dB. For a DSB mixer
(one without any image rejection), the value should be 0 dB. Using an
Image Rejection
value of 999.99 dB for a DSB measurement will produce measurement errors: the
measured noise figure will be 3 dB lower than the actual noise figure and the measured
gain will be 3 dB higher than the actual gain.
For comparison with noise test systems of other manufacturers, the
Image Rejection
should be set to 999.99 dB (SSB measurement) as this is the setting implicitly used by
almost all manufacturers.
2.4.1.8 Single Frequency Measurement
When the Single Frequency Measurement is selected (by checking the “Single Freq”
checkbox), the Stop and Step Frequency fields are disabled and the Stop Frequency is
always set to the Start Frequency value.
Thus the Frequency List contains only one value, giving quicker access to both Single
and Continuous measurements at that frequency.
2.4.2 Frequency Table
The
Frequency Table
lists each Receive Frequency (RF) at which a measurement will be
performed, along with the corresponding LO, IF & Image frequencies where appropriate.
Whilst the Frequency Table is normally generated automatically using the Frequency
Settings group of parameters on the left of the view, it is also possible to add individual
values directly into the Frequencies List on the right, including insertion and deletion of
measurement steps.
This allows specific adjustments to individual measurement steps to be made in order
to customise the automatically generated list, e.g. to insert extra measurement steps
near to a specific frequency of interest in order to get more detailed results (but without
losing the rest of the frequency range).
If the frequency table is manually modified, all changes will be lost if the start/stop/step
frequencies or mode parameters are changed as changing these parameters causes
the frequency list to be automatically generated. The frequency table can be
