Measurement Basics
R&S
®
FSW-K40
30
User Manual 1173.9286.02 ─ 15
4.7 Level Determination
Nominal level
The nominal level in other terms is the reference level of the R&S
FSW. This is the
level that the analyzer expects at the RF input.
The available level range depends on the hardware. For more information see the
datasheet of the R&S
FSW.
Make sure to define a level that is as close to the level of the DUT to get the best
dynamic range for the measurement. At the same time make sure that the signal level
is not higher than the reference level to avoid an overload of the A/D converter and
thus deteriorating measurement results.
If you are not sure about the power level of the DUT, but would still like to use the best
dynamic range and get results that are as accurate as possible, you can verify or track
the level.
Level verification
When you are using the level verification, the application initiates a measurement that
determines the level of the DUT. If the level of the DUT is within a certain tolerance
range, it will adjust the nominal level to that of the DUT. Else, it will abort the phase
noise measurement.
Define a level tolerance in relation to the current nominal level. The tolerance range
works for DUT levels that are above or below the current nominal level.
Level tracking
For tests on DUTs whose level varies, use level tracking. If active, the application
keeps track of the DUTs level during the phase noise measurement and adjusts the
nominal level accordingly.
For a graphical representation of level verification and level tracking see the figures in
Chapter 4.6, "Frequency Determination"
4.8 Signal Attenuation
Attenuation of the signal may become necessary if you have to reduce the power of
the signal that you have applied. Power reduction is necessary, for example, to prevent
an overload of the input mixer. An overload of the input mixer may lead to incorrect
measurement results or damage to the hardware if the signal power is too strong.
In the default state, the application automatically determines the attenuation according
to the reference level. If necessary, you can also define the attenuation manually.
When you attenuate the signal, the application adjusts graphical and numerical results
accordingly.
Signal Attenuation