Zooming can truncate waveform

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chalkie
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Zooming can truncate waveform

Post by chalkie »

Picoscope 5444B, Tested on Picoscope 6.9.14.16 and Picoscope 6.10.2.2 (Beta)

If the trigger is fired while zooming is active, then only the section of waveform currently zoomed to is shown correctly. If you change the zoom window, or close the zoom window then the waveform display is incomplete. If/When the trigger fires again, the the output is corrected. Please see the attached document which has screenshots.
Picoscope zoom window.pdf
(203.89 KiB) Downloaded 390 times
This is really only an issue for DUTs which generate infrequent triggers. So far as I can see a frequent trigger quickly obviates the issue.

Martyn
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Re: Zooming can truncate waveform

Post by Martyn »

This is the expected behaviour of the scope.

When the scope is waiting for data, and the trigger is armed, it is not able to transmit data across the USB bus to the PicoScope application. When a block of data has been collected on the scope the software will request the data to display on the screen. If the screen is zoomed, the application will only ask for data covering that particular section. This process helps to speed up the trigger re arm process ready to collect the next block of data. As the trigger is now re armed, if you zoom out the application will not be able to collect the extra data for the missing area and will only be able to display data from the previous zoomed region.

If at any stage you stop the capture, the complete trace will be drawn.
Martyn
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chalkie
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Re: Zooming can truncate waveform

Post by chalkie »

Oooh, that's true! If I press the stop button, the rest of the trace appears.

Good answer.

Chalkie.

driesdendas
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Re: Zooming can truncate waveform

Post by driesdendas »

Hello,

I think i've the same problem but with a saved waveform. When i zoom the waveform doenst cover the whole display. Is there a solution for this? When i importe the data in excell i see every sample.

Dries
Attachments
zoom.pdf
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lab!fyi
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Re: Zooming can truncate waveform

Post by lab!fyi »

BTW side effect of this expected behaviour is either completely or partially breaking math traces that have to do with time (filters, integrals etc), especially ones rendered over multiple previous buffers (average etc). Do not think that this kind of optimization is compatible with time-related math in principle. I have started to use trigger delay and changing timebase instead of zoom to partially work around this.

Martyn
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Re: Zooming can truncate waveform

Post by Martyn »

The pdf doesn't show us enough information, the psdata file would be better.
Martyn
Technical Support Manager

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