EEVblog Electronics Community Forum
Products => Test Equipment => Topic started by: MattFL on September 23, 2015, 12:03:11 pm
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Please help me figure out how to record this signal, I'm missing something that seems like it should be simple but I'm not sure what I'm looking for.
I'm using a Rigol DS2072A scope and it's got a cool feature where it only records when it thinks something is happening with the signal, so that memory isn't wasted by dead spots. I need to turn this off, the dead spots are important to me, but I don't know what setting I'm looking for.
Example case; the startup of a 12V DC power supply. The signal starts at 0V, jumps to 12V in a couple ms, then has some noise around 12V. I need to record about 2 seconds of this entire sequence. With the scope set to rising edge, DC coupling and the trigger level around 1V, I get a very nice recording of when the voltage is transitioning from 0V to 12V, but once it's at 12V the recording stops. How can I make it trigger on the rising voltage, but then keep recording even when it appears to the scope that nothing significant is happening? Did I explain this clearly?
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The waveform record and playback feature grabs one "frame" or waveform per trigger event. It's used for the situation where there IS a lot of non intersting "stuff" in between trigger events.
That's not what you want in this case. Instead, move the trigger position towards the left side of the screen (so you don't waste half the screen displaying pre-trigger data) then set your timebase to 200ms or 500ms per division.
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To expand on H.O, to be able to grabe 2+ seconds of data including the "dead spots", you are going to need to enable the full memory, and then see the sweep (horizontal) speed to 2+ sec. Then if you single-shot on what ever trigger event at the beginning of the sequence you are looking for (or simply let it run in free-running mode and then stop the sweep), you will get 2+ secs of data in your capture and you can zoom in and look at the waveform. But beware: if you need to look at a chunk of data over a few seconds, samples/sec will drop so you might miss out on details when you zoom into the waveform (for example, if there is a 5nsec event, you probably don't have enough memory to capture this event when capturing a 10second waveform).
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Thanks for the replies! I will give this a shot and report back.
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Thanks again for the tips, I think this will work. I only have the record function up to 100ms / division, any longer than that and the record function is unavailable. But that should be good enough for now. Maybe I can get enough data in one frame with the single shot setting. Now if I can just get the trigger to be consistent!