Concepts and Features
R&S
®
ZNB/ZNBT
84
User Manual 1173.9163.02 ─ 38
The stimulus hardkeys define the fixed stimulus frequency ("CW Frequency") and
the "Number of Points" of the measurement. The other sweep parameters (e.g. the
"Sweep Time") are set via CHANNEL – SWEEP > "Sweep Params".
●
"Time"
The stimulus hardkeys define the fixed stimulus frequency ("CW Frequency") and
the total sweep time ("Stop Time") of the measurement. The other sweep parame-
ters (e.g. the "Number of Points") are set via CHANNEL – SWEEP > "Sweep Par-
ams".
The sweep time is entered in seconds and must be positive.
The selected sweep range applies to all source and receive ports of the analyzer.
In arbitrary mode (with option R&S
ZNB/ZNBT-K4), you can define port-specific fre-
quencies and powers; see
Chapter 5.5.2.2, "Port Settings Dialog"
4.1.4.4
Stepped vs. Swept Mode
The R&S
ZNB/ZNBT provides two sweep modes: stepped mode and swept mode.
In stepped mode (default), the frequency is changed stepwise and sampling is per-
formed at a tuned frequency for each measurement point. In swept mode, on the other
hand, sampling is performed with the frequency always swept for each measurement
point. Since in stepped mode at each measurement point a certain time is required
until the frequency becomes stable, sweeps in swept mode are generally much faster
than in stepped mode - at the cost of a lower measurement precision.
Stepped Mode
f
measurement points
1
3
2
...
n
f
start
f
stop
...
Sampling
Swept Mode
f
measurement points
1
3
2
...
n
f
start
f
stop
...
Sampling
Apart from the loss in precision there may be other technical reasons that prevent the
swept mode from being advantageous. For instance if the sweep is triggered by events
caused by external devices such as part handlers, generators or power meters, the
sweep (implemented in hardware) has to be interrupted by the software on a regular
basis and cannot proceed autonomously after the initial phase lock.
If the swept mode is selected and the R&S
ZNB/ZNBT actually uses it (for at least one
segment), this is indicated in the status bar:
Basic Concepts