SIGLENT
SSA3000X User Manual 32
2.2.4.5 QPD Dwell Time
Dwell time is the measurement time at a single frequency. QPD detector gets its weighted
envelope response during dwell time. The longer dwell time is, the more sufficiently QPD detector
responses to a single frequency, the more accuracy the QPD detector envelope is.
Table 2-17 QPD Dwell Times
2.2.5 Trigger
The trigger type can be Free Run, Video or External.
1. Free Run
The trigger conditions are satisfied at any time and the analyzer generates trigger signals
continuously.
2. Video Trigger
A trigger signal will be generated when the system detects a video signal of which the voltage
exceeds the specified video trigger level.
Set the trigger level in video trigger. At this point, the trigger level line (Trig Line) and value are
displayed on the screen.
Table 2-18 Trigger Setup
3. External
In this mode, an external signal (TTL signal) is input from the [TRIGGER IN] connector at the rear
panel and trigger signals are generated when this signal fulfills the specified trigger edge condition.
Set the trigger edge in external trigger to the rising (Pos) or falling (Neg) edge of the pulse.