Common measurement settings
R&S
®
FSVA3000/ R&S
®
FSV3000
376
User Manual 1178.8520.02 ─ 08
next to the indication that an external generator is being used ("Ext.Gen").The normal-
ized trace from the calibration sweep is a constant 0
dB line, as <calibration trace> -
<reference trace> = 0.
As long as the same settings are used for measurement as for calibration
, the normal-
ized measurement results should not contain any inherent frequency or power distor-
tions. Thus, the measured DUT values are very accurate.
Approximate normalization
As soon as any of the calibration measurement settings are changed, the stored refer-
ence trace will no longer be identical to the new measurement results. However, if the
measurement settings do not deviate too much, the measurement results can still be
normalized
approximately
using the stored reference trace. This is indicated by the
"APX" label in the channel bar (instead of "NOR").
This is the case if one or more of the following values deviate from the calibration set-
tings:
●
Coupling (RBW, VBW, SWT)
●
Reference level, RF attenuation
●
Start or stop frequency
●
Output level of external generator
●
Detector (max. peak, min. peak, sample, etc.)
●
Frequency deviation at a maximum of 1001 points within the set sweep limits (cor-
responds to a doubling of the span)
Differences in level settings between the reference trace and the current instrument
settings are taken into account automatically. If the span is reduced, a linear interpola-
tion of the intermediate values is applied. If the span increases, the values at the left or
right border of the reference dataset are extrapolated to the current start or stop fre-
quency, i.e. the reference dataset is extended by constant values.
Thus, the instrument settings can be changed in a wide area without giving up normali-
zation. This reduces the necessity to carry out a new normalization to a minimum.
The normalized trace in the display
The normalized reference trace is also displayed in the spectrum diagram, by default at
the top of the diagram (= 100% of the window height). It is indicated by a red line
labeled "NOR", followed by the current reference value. However, it can be shifted ver-
tically to reflect an attenuation or gain caused by the measured DUT (see also
the reference line (and normalized trace)"
Restoring the calibration settings
If the measurement settings no longer match the instrument settings with which the
calibration was performed (indicated by the "APX" or no label next to "Ext.TG" in the
channel bar), you can restore the calibration settings, which are stored with the refer-
ence dataset on the R&S
FSV/A.
Data input and output
