Keysight Technologies 3458A Guide D'utilisation page 351

SSRC
Sync source. For sub-sampling (SSAC or SSDC command), the SSRC command
allows you to synchronize bursts to an external signal or to a voltage level on the
input signal.
For synchronous ACV or ACDCV (SETACV SYNC command), the SSRC command
allows you to synchronize sampling to an external signal. You can also use the
HOLD parameter to prevent the measurement method from changing to random
should level triggering not occur within certain time limits. The time limits are
determined by the AC bandwidth (ACBAND command) setting.
Syntax
SSRC [source][,mode]
source
The source parameter choices are:
source
parameter
EXT
LEVEL
[a] For synchronous ACV or ACDCV, the level triggering voltage (LEVEL command) and the slope (SLOPE command)
Power-on source = LEVEL
Default source = LEVEL
Keysight 3458A User's Guide
Numeric
query equiv.
2
[a]
7
are determined automatically and cannot be specified.
Description
Synchronize to external input on the rear panel Ext Trig connector
Synchronize to a voltage Level (LEVEL command> on the input
signal using the slope specified by the SLOPE command.
Command Reference 6
351