General Instrument Setup
R&S
®
FSVA3000/ R&S
®
FSV3000
605
User Manual 1178.8520.02 ─ 01
Transducer vs filter function
Touchstone files are handled similarly to transducer files by the R&S
FSV/A. However,
while a transducer adapts the frequency values by a fixed factor, Touchstone files act
as a filter on I/Q input data. For common frequency sweeps, the effects of transducers
and Touchstone files are the same.
.fres files
Additional frequency response correction files in
.fres
format allow you to correct
effects from components for which no Touchstone files are available.
Files in
.fres
format correspond to an S1P file. They contain exactly three values for
each frequency:
●
The frequency
●
The magnitude correction value
●
The phase correction value
Instead of the magnitude and phase correction values, the I and Q values can be provi-
ded.
These values are applied to the input data. If the file contains any other data, it can not
be loaded.
For
.fres
files, magnitude and phase correction can be activated separately.
Combining multiple Touchstone files
Since the measurement setup may consist of several cables, DUTs and other compo-
nents, multiple Touchstone and frequency response files can be required for full com-
pensation. In this case, the order in which the files are applied is important. The
R&S
FSV/A combines all active Touchstone files to a single S2P file, and creates the
required filter or correction factors for the measurement.
Correction filters for I/Q data
Filters can only be applied to I/Q data if they are defined for the complete analysis
bandwidth. Therefore, if the combined frequency response filter does not cover the
complete analysis span, it is invalid and cannot be used for the measurement. See
also
"Recognizing frequency response correction in measurement results"
on page 606.
For common frequency sweeps, values not covered by the combined frequency
response are not corrected, but the settings remain valid.
External preamplifier Touchstone files
If an external preamplifier is connected to the R&S
FSV/A, an additional Touchstone
file is provided by the preamplifier. The combined frequency response filter also con-
siders those values. For your convenience, the external preamplifier can be switched
on and off directly in the "User-Defined Frequency Rsponse Correction" dialog box, as
an alternative to the common input settings.
Frequency Response Correction (R&S
FSV/A-K544)
