Keysight Technologies 3458A Guide D'utilisation page 487

lets you specify the number of readings to take, the trigger condition for each
reading, and the number of readings saved in memory before or after the trigger
event.
The SWEEP and SSRC commands are specifically designed to make the task of
digitizing easier. The
SWEEP [effective interval between readings] [, number of readings]
command combines the NRDGS parameters with TIMER. SSRC selects the
synchronizing source for subsampling, either external or level. Both the SWEEP
and SSRC commands are used for SSAC (subsampled, AC coupled) and SSDC
(subsampled, DC coupled), and the NRDGS and TRIG are ignored. For DSAC
(direct sampled, AC coupled) and DSDC (direct sampled, DC coupled) all
triggering commands are valid but the use of both in the same measurement is
not recommended.
Figure E-7
The SSRC command offers you either internal level triggering or synchronization
with the external trigger. In the subsampling mode, the SSRC EXT calculates the
number of external triggers it needs to accomplish the measurement you specify
with the SWEEP command.
For example, if you want to capture a wave form with 100 ns time resolution for
4096 readings
[SWEEP 100E-9,4096]
Keysight 3458A User's Guide
High Resolution Digitizing With the 3458A
Once the trigger arming and trigger event conditions are
satisfied, a burst of measurements can digitize a wave form as
shown in this example.
E
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