R&S ZVL GUI Reference
Trace Menu
Operating Manual 1303.6580.32-06
145
that the frequency grid must be harmonic. Due to the symmetry of the trace in the frequency
dom
ai
n, the time domain result is harmonic.
The band pass and low pass modes are compared below.
Transform
type
Band pass Low pass
Advantages
Easiest to use: works with any set of equidistant sweep
points
Higher response resolution (doubled)
Includes information about DC value
Real result
Impulse and step response
Restrictions No step response
Undetermined phase
Needs harmonic grid
Use for... Scalar measurements where the phase is not needed
DUTs that don't operate down to f = 0 (e.g. pass band or
high pass filters)
Scalar measurements where the sign is of
interest
DUT's with known DC value
Remote control:
CALCulate<Chn>:TRANsform:TIME[:TYPE]
Impulse and Step Response
In low pass mode, the analyzer can calculate two different types of responses:
• The impulse response corresponds to the response of a DUT that is stimulated with a short pulse.
• The step response corresponds to the response of a DUT that is stimulated with a voltage
waveform that transitions from zero to unity.
The two alternative responses are mathematically equivalent; the step response can be obtained by
integrating the impulse response:
Integrate impulse response
Obtain step response
The step response is recommended for impedance measurements and for the analysis of discontinuities
(especially inductive and capacitive discontinuities). The impulse response has an unambiguous
magnitude and is therefore recommended for most other applications.
Remote control:
CALCulate<Chn>:TRANsform:TIME:STIMulus
Windows in the Frequency Domain
The finite sweep range in a frequency domain measurement with the discontinuous transitions at the start
and stop frequency broadens the impulses and causes sidelobes (ringing) in the time domain response.
The windows offered in the Define Transform dialog can reduce this effect and optimize the time domain
response. The windows have the following characteristics:
Window Sidelobe suppression Relative impulse
width
Best for...
No Profiling
(Rectangle)
13 dB 1 –
Low First Sidelobe
(Hamming)
43 dB 1.4
Response resolution: separation of closely
spaced responses with comparable amplitude
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