oneshot mode the acquisition has to be manually (re)started by pressingthe button next to the list box or by pressing the Trigger button, whenusing the Integrated PC Mode. To stop measuring in continuous modeselect Hold from the drop-down menu or by pressing the Stop buttonrespectively.6.1.4 Edge DetectionIf the SOP changes rapidly during the observed time frame, a reduceddegree of polarization (DOP) may be observed. This happens when theSOP instantaneously changes within a sampling interval. Although thisis a correct readout since the DOP is in fact reduced within that shortmoment it is sometimes desired to avoid sampling on those edges.Specifically this applies to measurements, where the SOP is expected tostay in fixed positions for certain intervals and change very quickly inbetween (e.g. when using an adaptif PHOTONICS A3XXX as a scram-bler). If no synchronization method is used, the abovementioned effectwill occur.Activate Lock to Edges to detect and avoid such edges.NOTE: This operation uses 6 x oversampling and is thus only availablefor sampling rates below 160 kHz.6.1.5 TriggeringYou can synchronize the start of a measurement cycle to certain eventssuch as an external trigger signal.Select TTL High or TTL Low from the Trigger list box to choose thedesired trigger edge of an externally applied digital signal. The signal hasto be applied to the BNC input named Trig. In. The actual measurementis performed continously, so the trigger event defines the portion of themeasured data stream to be shown. You can set the number of samplesto be stored from right before the trigger event (Pre-Trig. Samples) andright after the trigger event (Post-Trig. Samples).A1XXX/A2XXX/A3XXX User Guide 35
