bug report: wrong number of samples

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stevenvh
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bug report: wrong number of samples

Post by stevenvh » Sun Mar 22, 2015 5:43 pm

I select 10kS, but PicoScope shows 15,000 samples in the Properties windows, and also applies this number. Changing the number of samples has no effect to the Properties window: remains at 15,000.
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Hitesh
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Re: bug report: wrong number of samples

Post by Hitesh » Mon Mar 23, 2015 12:29 pm

Hi stevenvh,

My understanding is that this is by design in the software.

Capturing at very slow rates can cause problems such as a very long delay when starting sampling (it also relates to the trigger circuit).

I will update a feature request relating to this.

Regards,
Hitesh

Technical Support Engineer

stevenvh
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Re: bug report: wrong number of samples

Post by stevenvh » Mon Mar 23, 2015 1:02 pm

Thanks Hitesh. Your explanation seems to make sense: it happens for all sample counts less than or equal to 10,000, and doesn't occur at 100ms/div or less. I can understand that missing the trigger could be a bad thing, but I think you (PicoTech) should trust that an engineer knows how to operate a scope, and allow her to make the settings she wants.
In my case I'm working with no trigger and I wanted 10kSamples over a 10 second period (1s/div), so that would be a nice 1 ms/sample. Instead I get 0.667ms/sample.

A solution could be to place a warning icon next to the selected number of samples when the sample rate becomes too slow. Clicking the icon could show a dialog where the user could override her choice and go for the minimum of 15,000. That number could go in the system preferences.

Martyn
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Re: bug report: wrong number of samples

Post by Martyn » Tue Mar 24, 2015 7:16 am

If you go to Tools->Preferences->Sampling and change the Slow Sampling Transition time to say 10s/div, you will be able to capture 10000 samples at 1s/div with 1ms sample interval. The scope will be operating in block mode where it captures the data to it's buffer before transferring to the PC, however you will not be able to see the trace update live on the screen.
Martyn
Technical Support Manager

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