Agilent Technologies ENA Series User Manual page 417

Swept mode
As shown in Figure 12-6, in the stepped mode, the frequency is changed stepwise and
sampling is performed at a fixed frequency for each measurement point. On the other hand,
in the swept mode, sampling is performed with the frequency always swept for each
measurement point.
NOTE When the IF bandwidth is 5 kHz or less, the sweep is performed in the stepped mode even
if the swept mode has been specified (the fast stepped mode when the fast swept mode is
specified).
Figure 12-6 Difference between stepped and swept modes
In the stepped mode, a certain time should be allowed until the frequency becomes stable at
each measurement point, since the frequency is changed stepwise. Therefore, the sweep
time in the swept mode is generally shorter than that in the stepped mode. However, if the
measurement point interval is extremely large, the sweep to the next measurement point
frequency cannot be completed within the sampling time due to the limitations of the
instrument's frequency sweep speed. This causes a certain waiting time until the start of
measurement of the next measurement point, and thus in this case the swept mode actually
has a longer sweep time.
Although there is some difference depending on the IF bandwidth setting, when the
measurement point interval is approximately 10 MHz or less (approximately 30 MHz or
less for the fast mode), the sweep time in the swept mode is shorter than that in the stepped
mode.
Note that the swept mode has the following disadvantages.
• DUTs with long electrical delay time cannot be measured correctly. For more
information, refer to "Notes for measuring DUTs with long electrical delay time" on
page 412.
• Trace noise may increase compared to the stepped mode because sampling is
performed while sweeping the frequency.
• The specifications are not guaranteed
NOTE When you use the swept mode, you should confirm that there is no measurement-related
Chapter 12
Optimizing Measurements
Improving Measurement Throughput
411