R&S ZVL
GUI Reference
Trace Menu
Operating Manual 1303.6580.32-06
142
Trace settings in time domain representation
While the time domain representation is active the trace settings behave as follows:
•
The settings in the
Stimulus Transform
submenu configure the time axis.
•
All Trace Formats including the circular diagrams are available.
•
Limit lines can be defined like the limit lines for time sweeps.
•
The bandfilter search functions are available for the transformed trace.
•
If marker coupling is active, then the markers in the time domain and in the frequency domain are
coupled with each other.
The analyzer places no restriction on the measured quantities to be transformed into the time domain.
Impedances and admittances are first converted back into the equivalent S-parameter, transformed, and
restored after the transformation.
Properties of the Chirp z-transformation
The Chirp z-transformation that the analyzer uses to compute the time domain response is an extension of
the (inverse) Fast Fourier Transform (FFT). Compared to the FFT, the number of sweep points is arbitrary
(not necessarily an integer power of 2), but the computation time is increased by approx. a factor of 2.
This increased computation time is usually negligible compared to the sweep times of the analyzer.
The following properties of the Chirp z-transformation are relevant for the analyzer settings:
•
The frequency points must be equidistant. If a
Log Frequency
or
Segmented Frequency
sweep is
active, the measurement points are interpolated.
•
The time domain response is repeated after a time interval which is equal to
Q
t = 1/
Q
f, where
Q
f is
the spacing between two consecutive sweep points in the frequency domain. For a sweep span of
4 GHz and 201 equidistant sweep points,
Q
f = 4 GHz/200 = 2 * 10
7
Hz, so that
Q
t = 50 ns. t is
termed measurement range (in time domain) or unambiguous range.
Additional constraints apply if the selected Chirp z-transformation is a lowpass transformation.
Remote control:
CALCulate<Chn>:TRANsform:TIME:STATe ON
Stimulus Transform
Opens a submenu to define the stimulus axis range for time domain representation.
