R&S ZVB - Page 279

R&S
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ZVA / R&S
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ZVB / R&S
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ZVT GUI Reference
Channel Menu
Operating Manual 1145.1084.12 – 30 264
The sweep segment file actually contains more columns listing all channel settings of the
individual sweep segments. The headings of the additional columns read:
Source Power [dBm]; IF Bandwidth [Hz]; enIF Selectivity; en IF Sideband; Meas Delay [  s];
boSweep Time Auto;
Pulsed Measurements (for R&S ZVA and R&S ZVT)
The softkeys in the lower part of the Sweep Type submenu control pulsed measurements (with option
ZVA-K7, Pulsed Measurements).
Pulse profile mode
Measurements on pulsed RF signals are required in many areas of RF and microwave
technology. Pulsed signals are used in mobile phone applications and radar systems, and
amplifiers are typically designed for pulsed rather than continuous wave (CW) conditions.
The analyzer performs pulsed measurements in analogy to a time sweep (i.e. at constant
receiver frequency), but with a much higher sampling rate of 1/12.5 ns. The raw I/Q
amplitudes are written into a ring buffer and processed at the end of each sweep. The buffer
size allows for a maximum recording time (sweep time) of 3 ms. Due to the high sampling
rate and the large IF bandwidths available, it is possible to obtain profiles for pulse widths
from approx. 200 ns to the maximum recording time. Of course it is also possible to measure
a sequence of pulses up to the maximum recording time.
Pulsed measurements require a trigger signal that is synchronized to the analyzed pulses.
The analyzer's trigger system is idle while the data acquired in the last recording period is
processed; it is re-armed after data processing is finished. To suppress the noise occurring at
high IF bandwidths, sweep averaging is recommended.
The RF source signal of the vector network analyzer is continuous, so the pulsed stimulus
signals must be generated by external means:
 Preferably, an R&S ZVAX extension unit equipped with one or more pulse modulator
options provides the pulsed signal. The pulse modulators are controlled using the
internal pulse generator of the network analyzer; see measurement example for
pulse modulators.
 Alternatively, a chopper between the SOURCE OUT and the SOURCE IN connector
of an analyzer port transforms the continuous source signal into a pulsed signal.
 An external generator can provide pulsed signals.
 The DUT can be switched on and off periodically to show a pulsed characteristic.
Basic relations: pulse width, repetition interval, IF bandwidth
A pulsed RF signal ideally consists of a sequence of periodic rectangular pulses. The pulse
width PW and pulse repetition period PRP are shown in the following figure; the ratio
PW/PRP is often referred to as the duty cycle.