R&S ZVB - Page 184

R&S
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ZVA / R&S
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ZVB / R&S
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ZVT GUI Reference
Trace Menu
Operating Manual 1145.1084.12 – 30 169
An independent Time Gate can be used after the transformation in order to eliminate unwanted
responses.
Remote control:
CALCulate<Chn>:TRANsform:TIME[:TYPE]
CALCulate<Chn>:TRANsform:TIME:STIMulus
CALCulate<Chn>:TRANsform:TIME:WINDow
CALCulate<Chn>:TRANsform:TIME:DCHebyshev
CALCulate<Chn>:TRANsform:TIME:RESolution:EFACtor
Band Pass and Low Pass Mode
The analyzer provides two essentially different types of time domain transforms:
 Bandpass mode : The time domain transform is based on the measurement results obtained in
the sweep range between any set of positive start and stop values. The sweep points must be
equidistant. No assumption is made about the measurement point at zero frequency (DC value).
The time domain result is complex with a generally undetermined phase depending on the delay
of the signal.
 Low pass mode : The measurement results are continued towards f = 0 (DC value) and mirrored
at the frequency origin so that the effective sweep range (and thus the response resolution) is
more than doubled. Together with the DC value, the condition of equidistant sweep points implies
that the frequency grid must be harmonic. Due to the symmetry of the trace in the frequency
domain, the time domain result is real valued.
The bandpass and lowpass modes are compared below.
Transform
type
Bandpass
Lowpass
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
highpass 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: