Rigol RSA Series - Page 44

RIGOL Chapter 2 Functions of the Front Panel
2-24 VNA User Guide
Table 2-18 Average Count
Parameter
Remarks
Default
100
Range
1 to 10,000
Unit
N/A
Knob Step
1
Left/Right Arrow Key Step
Up/Down Arrow Key Step
10
Ref Level
Indicates the reference level of the receiver channel of the spectrum analyzer. The
reference level for S11 measurement is a fixed value 0 dBm and it cannot be
modified.
Aperture Step Width
Sets the aperture step width. The aperture step width k determines the value for
group delay . VNA can measure S-parameters at the discrete frequencies.
Frequency step , aperture step width .
Group delay is obtained through differentiation calculation based on the phase of
S11 or S21, then obtain the result by weight method through the factor (take
S21 as an example).
Wherein, indicates the aperture. The measurement accuracy of group delay is
determined by the aperture that you use. If it is too large, it will affect the details;
if it is too small, it will produce more noises. There is no standard rule for aperture
selection, and you can only rely on experience in choosing it.