Using a Scope to Capture Transient Events.

There is often a need to capture the details of an event that happens at a low frequency or infrequently. To see the details of the event, an Oscilloscope needs to sample quickly.

In normal operation, a scope waits for a trigger and then acquires enough samples to fill the available memory. In this model, capturing low duty cycle or transient signals with high time resolution requires lots of memory.

Siglent’s Sequence operation addresses this problem. In this mode, the scope’s memory is divided into a many smaller sized “blocks” or segments that get filled on a trigger. With this mode, a memory Segment can be filled at high speed, but only a small section of the scope’s memory is filled with each trigger. The diagram shown below illustrates the concept.

With the scope triggering on each event, a copy of the event is stored in a subsection of the Scope’s memory.

It should be noted that no display is presented on the scope until after all the segments have been filled.

The history function of the scope provides access to all the acquired data. The utility can be used to review a specific segment or be programmed to automatically scroll through the segments much like a movie or video.

There are many parameters that set the operation of the sequence mode. The major ones include:

The sample rate of the A/D

the number of active channels, 

the horizontal scan rate, 

and the number of segments chosen.

Shown below is a summary of the interactions of these parameters on SDS824X-HD with a single active channel set to sample at 2 Ghz