Rohde & Schwarz FSW Series, User Manual

Page: 57 / 371

Configuration
R&S
®
FSW-K7
57 User Manual 1173.9240.02 ─ 17
This function is not available for input from the Digital Baseband Interface (R&S FSW-
B17) or from the Analog Baseband Interface (R&S FSW-B71).
AC coupling blocks any DC voltage from the input signal. This is the default setting to
prevent damage to the instrument. Very low frequencies in the input signal may be dis-
torted.
However, some specifications require DC coupling. In this case, you must protect the
instrument from damaging DC input voltages manually. For details, refer to the data
sheet.
Remote command:
INPut:
​
COUPling
​
on page 182
Impedance
The reference impedance for the measured levels of the R&S FSW can be set to 50
Ω
or 75
Ω
.
75
Ω
should be selected if the 50
Ω
input impedance is transformed to a higher impe-
dance using a 75
Ω
adapter of the RAZ type (= 25
Ω
in series to the input impedance
of the instrument). The correction value in this case is 1.76 dB = 10 log (75
Ω
/50
Ω
).
This value also affects the unit conversion (see "Reference Level" on page 86).
This function is not available for input from the Digital Baseband Interface (R&S FSW-
B17) or from the Analog Baseband Interface (R&S FSW-B71). For analog baseband
input, an impedance of 50
Ω
is always used.
Remote command:
INPut:
​
IMPedance
​
on page 183
High-Pass Filter 1...3 GHz
Activates an additional internal high-pass filter for RF input signals from 1 GHz to
3 GHz. This filter is used to remove the harmonics of the R&S FSW in order to mea-
sure the harmonics for a DUT, for example.
This function requires option R&S FSW-B13.
(Note: for RF input signals outside the specified range, the high-pass filter has no
effect. For signals with a frequency of approximately 4 GHz upwards, the harmonics
are suppressed sufficiently by the YIG filter.)
Remote command:
INPut:
​
FILTer:
​
HPASs[:
​
STATe]
​
on page 183
YIG-Preselector
Activates or deactivates the YIG-preselector.
An internal YIG-preselector at the input of the R&S FSW ensures that image frequen-
cies are rejected. However, this is only possible for a restricted bandwidth. In order to
use the maximum bandwidth for signal analysis you can deactivate the YIG-preselector
at the input of the R&S
FSW, which may lead to image-frequency display.
Input and Frontend Settings