Rohde & Schwarz 1145.1010.04/05/06, Operating Manual

Page: 200 / 813

Trace Menu R&S
®
ZVA/ZVB/ZVT
1145.1084.12 4.38 E-6
Properties: The delay at each sweep point is computed as:
where the aperture f is a finite frequency interval around the sweep point f
o
and the analyzer measures
the corresponding phase change .
Calculation of f and
With a given number of aperture steps n the delay at sweep point no. m is calculated as follows:
•
If n is even (n = 2k), then f (m) = f (n+k) – f (n–k) and
(
m
)=
(n+k) – (n–k).
•
If n is odd (n = 2k+1), then f (m) = f (n+k) – f (n–k–1) and
(
m
)=
(n+k) – (n–k–1).
It may be noted that the delay calculation is based on the already measured sweep points and does not
slow down the measurement.
f is constant over the entire sweep range, if the sweep type is a Lin. Frequency sweep. For Log.
Frequency and Segmented Frequency sweeps, it varies with the sweep point number m.
Application The aperture must be adjusted to the conditions of the measurement. A small aperture
increases the noise in the group delay; a large aperture tends to minimize the noise effects, but at the
expense of frequency resolution. Phase perturbations which are narrower in frequency than the
aperture tend to be smeared over and can not be measured.
SWR
Calculates the Standing Wave Ratio (SWR) from the measured quantity (primarily: from a reflection S-
parameter) and displays it in a Cartesian diagram.