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How to measure the rise time? Results are emty.

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How to measure the rise time? Results are emty.

Postby Manfred » Tue Apr 17, 2018 9:40 am

Hello,

I like to calculate the rise time. The measurements are added, but I do not get a result. What wrong with the configuration?

Sreenshot.png
Screenshot


Best regards,

Manfred
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Re: How to measure the rise time? Results are emty.

Postby bennog » Tue Apr 17, 2018 5:04 pm

That is because it is measure between rulers (the white square dots) not the green ones.
And between the white square dots are no rising edges, so it can not calculate the rise time.

Just my 2c.

Benno
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Re: How to measure the rise time? Results are emty.

Postby sbabic44 » Tue Apr 17, 2018 8:25 pm

You are not using time rulers (square ones, you pull them from left side). You are using phase rulers (round ones, you pulled them from right side). Check help documentation..
Regards,

Sinisa
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Re: How to measure the rise time? Results are emty.

Postby Martyn » Wed Apr 18, 2018 8:51 am

Alternatively if you use the PicoScope 6.13 Beta, which will be going stable soon, you can use the Deep Measure feature
DeepMeasure.jpg
DeepMeasure
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Re: How to measure the rise time? Results are emty.

Postby Manfred » Wed Apr 18, 2018 1:24 pm

Thank you for your replays.

Now I changed the rulers and measurements. For the first measure I get no min/max values and for the second measure I get all values. What can be the reason for this different behaviour?

Screenshot.png
Screenshot
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Re: How to measure the rise time? Results are emty.

Postby bennog » Wed Apr 18, 2018 3:20 pm

Can you remove the resolution enhancement.

Because i think this is smoothing your fall and rise times.

Edit:
Build test setup with 100kHz signal gen square wave.
Difference in rise time with and without is 20 fault ! this is even worse than I expected.

100khz without RE.png
100khz signal without resolution enhancement


100khz with RE.png
100khz signal with resolution enhancement


P.S. I noticed that when there are a lot of zero crossings between rulers the Rise time calculation stops for some strange reason, this is probably a bug in the PS software.

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Re: How to measure the rise time? Results are emty.

Postby alan » Fri Apr 20, 2018 5:04 am

To measure rise time accurately there need to be several samples on the rising edge of the square wave. As its a vertical edge there may not be enough samples - try using a shorter timebase so there are less square waves / edges on the screen. This should increase the number of samples used to make the measurement.

As Martyn says you could also try DeepMeasure which will provide a separate measurement for each rising edge on the screen.
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