Rohde & Schwarz R&S FSP Series, Operating Manual

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R&S FSP Instrument Functions
Analyzer Mode
4.18 Operating Manual 1164.4556.12 - 06
The attenuation can be varied in 5 dB steps from 0 to 30 dB. Other entries are
rounded to the next lower integer value.
If the defined reference level cannot be set for the given RF attenuation, the refer-
ence level will be adjusted accordingly and the warning "Limit reached" will be out-
put.
Remote command:
INP:EATT:AUTO OFF
INP:EATT 10 DB
This function is only available with option ELECTRONIC ATTENUATOR B25.
EL ATTEN
AUTO The EL ATTEN AUTO softkey switches the electronic attenuator on and automati-
cally sets its attenuation to 0 dB.
The allowed setting range of the reference level ranges from the current reference
level on switching on the electronic attenuator to over 30 dB. If a reference level is
set outside the allowed 30-dB range, setting is performed by means of the mechani-
cal attenuator. From this new reference level to over 30 dB the setting is again per-
formed with the electronic attenuator.
Remote command:
INP:EATT:AUTO ON
This function is only available with option ELECTRONIC ATTENUATOR B25.
EL ATTEN OFF The EL ATTEN OFF softkey switches the electronic attenuator off.
Remote command:
INP:EATT:STAT OFF
This function is only available with option ELECTRONIC ATTENUATOR B25.
RF INPUT
(50
Ω
75
Ω
)
The RF INPUT (50
Ω
75
Ω)
softkey switches the input impedance of the instrument
between 50
Ω
(= default setting) and 75
Ω
.
The setting 75
Ω
should be used if the input impedance (50
Ω
) is transformed to 75
Ω
using the corresponding adapter unit of type RAZ (= 25
Ω
in series to the input
impedance of the R&S FSP). The correction value used for the adoption is 1.76 dB
= 10 log (75
Ω
/ 50
Ω
).
All levels specified in this operating manual refer to the default setting of the instru-
ment (50
Ω
).
Remote command:
INP:IMP 50OHM
4.5.4 Setting the Bandwidths and Sweep Time – BW Key
The BW key calls a menu for setting the resolution bandwidth ( RBW ), video band-
width ( VBW ) and sweep time ( SWT ) for the frequency sweep. The parameters may
be coupled dependent on the span (stop minus start frequency) or freely set by the
user. When working with a split screen display, the settings always refer to the active
window.
The R&S FSP offers resolution bandwidths from 10 Hz to 10 MHz in 1, 3, 10 steps.
Resolution bandwidths up to 100 kHz are realized using digital bandpasses with
Gaussian characteristics. As far as the attenuation characteristic is concerned they
behave like analog filters but have a much higher measurement speed than compa-
rable analog filters. This is due to the fact that the transient response can be com-
pensated as a result of an accurately defined filter behavior.