Picoscope 6404D Signal Generator Trigger Latency

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Ivan Popov
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Picoscope 6404D Signal Generator Trigger Latency

Post by Ivan Popov » Thu Aug 29, 2019 9:23 am

Hello,

I am running the following setup - I am using a Picoscope 6404D, to input channel A I have connected an external signal generator output, generating a rectangular signal with amplitude 2V and width 500 ps. I have set the trigger to Pulse Width and have set an alarm to trigger the Picoscope's internal signal generator as soon as a waveform is captured, following the instructions from the manual. The output of the internal signal generator was then plugged in input channel B. My goal was to use the alarm as a fast trigger, but to do that I need to know the latency between the alarm and the waveform capture. Unfortunately instead of a square signal I get a straight line, which I can't use for timing purposes. Is it even possible to use the internal signal generator in such a way? I have attached a screenshot from the Picoscope 6 software and a PSData file from a single capture.
20190829-0001.psdata
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screenshot.PNG

NeilH
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Re: Picoscope 6404D Signal Generator Trigger Latency

Post by NeilH » Tue Sep 03, 2019 9:41 am

Hi

The alarm wouldn't trigger the signal generator till after the capture has completed, if you want to trigger the signal generator during the capture you would need to use the Triggers option under the Signal Generator to use the scope trigger

Neil
Neil
Technical Support Engineer

Ivan Popov
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Re: Picoscope 6404D Signal Generator Trigger Latency

Post by Ivan Popov » Tue Sep 03, 2019 12:30 pm

Thank You, Neil!
Your answer was very useful! I have one follow-up question. I want to use the signal from the picoscope's signal generator as a fast trigger for a specific type of pulse, namely pulses with width above 600 ns (like the one in the screenshot in my original post) and I need as fast response as possible from the signal generator, preferably before even the pulse itself has reached its falling edge. From what I was able to see though the signal from the signal generator is dependent on the falling edge of the pulse, i.e no matter how long the pulse is, the signal generator outputs a signal AFTER a falling edge is detected (look at the two screenshots I have attached in this reply, in one the pulse width is roughly 1400 ns, in the other - roughly 700 ns, in both the signal generator outputs a signal roughly 400 ns after the falling edge of the pulse). My question is if it is possible to make it dependent on the rising edge, so as soon as there is a rising edge and the pulse continues for more than 600 ns the signal generator outputs a signal?

Thank You for the support and have a nice day!
Ivan Popov
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Capture2.PNG
Capture1.PNG

NeilH
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Re: Picoscope 6404D Signal Generator Trigger Latency

Post by NeilH » Tue Sep 03, 2019 12:59 pm

Hi

You would need to change the scope trigger to meet those requirements to have the signal generator trigger like that, as it is sharing it with the data capture as well. Are you able to give a sketch of your signal over several buffer lengths with where you would like to trigger your signal generator and your data capture on the sketch so we can work out what you would want to have the trigger set up as.

Neil
Neil
Technical Support Engineer

Ivan Popov
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Re: Picoscope 6404D Signal Generator Trigger Latency

Post by Ivan Popov » Tue Sep 03, 2019 1:38 pm

Hello!
Thank You for the fast reply. I have attached a rough sketch of what I'm trying to achieve. The signals I am working with are of a certain amplitude and with varying widths. I need to trigger on them as soon as the width exceeds a specific threshold, say for example 1 microsecond, even if no falling edge is detected (sometimes those signals can be with width of a couple of milliseconds and I need the trigger to be as fast as possible). So basically as soon as a rising edge is detected and the width exceeds 1 microsecond I need it to trigger. I am sorry if my explanation is a bit confusing.

Best regards,
Ivan Popov
Attachments
Scanned_from_a_Lexmark_Multifunction_Product03-09-2019-151830.pdf
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