Common Measurement Settings
R&S
®
FSW
361User Manual 1173.9411.02 ─ 19
biasing it is not important to know the exact current flowing through the diode since the
conversion loss must be set to a minimum with the frequency. Therefore, it makes no
difference whether the setting is performed by an open-circuit voltage or by a short-cir-
cuit current. A DC return path is ensured via the 66 Ω resistor, which is an advantage
in some mixers.
Conversion Loss Tables
Conversion loss tables consist of value pairs that describe the correction values for
conversion loss at certain frequencies. Correction values for frequencies between the
reference values are obtained by interpolation. Linear interpolation is performed if the
table contains only two values. If it contains more than two reference values, spline
interpolation is carried out. Outside the frequency range covered by the table the con-
version loss is assumed to be the same as that for the first and last reference value
(see figure 6-15).
Fig. 6-15: Conversion loss outside the band's frequency range
Predefined conversion loss tables are often provided with the external mixer and can
be imported to the R&S FSW. Alternatively, you can define your own conversion loss
tables. Conversion loss tables are configured and managed in the "Conversion loss
Table Settings" tab of the "External Mixer Configuration" dialog box (see "Managing
Conversion Loss Tables" on page 372).
Importing CVL tables
The conversion loss table to be used for a particular range is also defined in the "Exter-
nal Mixer Configuration" dialog box. All tables stored on the instrument in the
C:\r_s\instr\user\cvl\ directory are offered for selection. A validation check is
then performed on the selected table to ensure that it complies with the settings. In
particular, the following is checked:
●
the assigned band name
●
the harmonic order
●
the mixer type
Data Input and Output
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