User Manual

The Spectrum Application (RF Measurements)
R&S
®
FPL1000
313User Manual 1178.3370.02 ─ 09
If necessary, you can optimize the reference level further. Decrease the attenuation
level manually to the lowest possible value before an overload occurs, then decrease
the reference level in the same way.
You can change the measurement time for the level measurement if necessary (see
"Changing the Automatic Measurement Time (Meastime Manual)" on page 345).
Remote command:
[SENSe:]ADJust:LEVel on page 766
Attenuation Mode / Value
The RF attenuation can be set automatically as a function of the selected reference
level (Auto mode). This ensures that no overload occurs at the RF Input connector for
the current reference level. It is the default setting.
In "Manual" mode, you can set the RF attenuation in 5 dB steps down to 0 dB (with
option R&S FPL1-B22: in 1 dB steps). Other entries are rounded to the next integer
value. The range is specified in the data sheet. If the defined reference level cannot be
set for the defined RF attenuation, the reference level is adjusted accordingly and the
warning "limit reached" is displayed.
NOTICE! Risk of hardware damage due to high power levels. When decreasing the
attenuation manually, ensure that the power level does not exceed the maximum level
allowed at the RF input, as an overload may lead to hardware damage.
For details, see Chapter 7.5.1.2, "RF Attenuation", on page 309.
Remote command:
INPut<ip>:ATTenuation on page 778
INPut<ip>:ATTenuation:AUTO on page 778
Impedance
For some measurements, the reference impedance for the measured levels of the
R&S FPL1000 can be set to 50 Ω or 75 Ω.
Select 75 Ω if the 50 Ω input impedance is transformed to a higher impedance using a
75 Ω adapter of the RAZ type. (That corresponds to 25Ω in series to the input impe-
dance of the instrument.) The correction value in this case is 1.76 dB = 10 log (75Ω/
50Ω).
This value also affects the unit conversion (see "Reference Level" on page 311).
Remote command:
INPut<ip>:IMPedance on page 790
Preamplifier
If the (optional) internal preamplifier hardware is installed, a preamplifier can be activa-
ted for the RF input signal.
You can use a preamplifier to analyze signals from DUTs with low output power.
Note that if an optional external preamplifier is activated, the internal preamplifier is
automatically disabled, and vice versa.
The input signal is amplified by 20 dB if the preamplifier option is activated.
Remote command:
INPut<ip>:GAIN:STATe on page 779
Amplitude and Vertical Axis Configuration