Keysight EXG and MXG X-Series Signal Generators User’s Guide 129Optimizing Performance for All ModelsUsing Free Run, Step Dwell, and Timer TriggerUsing Free Run, Step Dwell, and Timer TriggerFree Run, Step Dwell (time), and Timer Trigger can be used to adjust the time spent at any point ina Step Sweep or a List Sweep. There are two possible measurement combinations:Free Run with Step Dwell time (Figure 5-27 on page 130) the signal generator waits for the signalto settle and then waits for the Step Dwell time, then it jumps to the next frequency point. Inaddition, the time to complete the entire sweep can vary. There is always a minimum value of StepDwell for each frequency point. The minimum Step Dwell timing for any point is fixed at a value of100 us. The time between frequency points is the sum of the settling time, plus the Step Dwell time.The settling time is dependent on frequency, amplitude, band crossings, and other factors, so thetime between frequency points can vary.Timer Trigger instead of Free Run (Figure 5-27 on page 130) the signal generator generatesequally spaced triggers, and it moves to the next point at each trigger. This has the advantage thatthe time between points is consistent and the overall sweep time is consistent. But, if the trigger istoo fast, the signal may not have time to settle before jumping to the next point.Understanding Free Run, Step Dwell, and Timer Trigger SetupIf the signal is to be settled for a minimum specific time at each point and it is not important if thepoint to point time is consistent, use Free Run and Set Dwell time.If the signal’s point to point time requires consistency but the specific settling time at each pointcan vary, then use the Timer Trigger. Avoid using too fast of a sweep which does not allow thesignal generator to settle.If the signal needs to be settled for a specific minimum time and consistent point to point time isrequired, then you should set the Timer Trigger to be the sum of the switching time (900 us or 5 ms,depending on options) plus the minimum settled time that is needed to make the measurement.If the measurement requires external equipment synchronization, consider using hardware triggers.
