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Standardised Way To Test Oscilloscope Screen Update Rate

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EEVblog:

--- Quote from: moerm on April 29, 2024, 10:42:44 pm ---Maybe Dave can (and should) tell us, what he wants to measure. Anyway, thank you Dave! While I'm not happy as an engineer (I was told that measuring is not guessing) I think you created a really interesting topic that I hope will keep our minds busy.

--- End quote ---

Basically I want to measure how fast the screen is updated with new waveform information.
Assuming the actual (capture) waveform update rate is way faster that human perception (let's say a standard 60wfs or faster), then how quickly is that information relayed to the screen.
Of course this is the #1 thing that the gamer kiddies care about, why should we care about thsi on a scope also.

If two scopes are equal in everything else and one updates the screen waveform at 60wfs and one updates at 5wfs I guarantee you are going to think the 5wfs scope seems "slow"

I like pdenisowski's "pixels changing" definition, so any test source need to have "pixels changing" at a fast enough rate to make the measurement possible.

David Hess:
I think the old DPO style instruments updated at the display's frame rate, so 30 or 60 Hz.

For measuring the update rate, I would use the same method as used for mechanical camera shutters.  Create a fast series of pulses with a variable but increasing delay, and then measure the width of the captured set of pulses, which will reveal how much time is displayed on each screen refresh, like a streak camera.  This relies on external triggering.

joeqsmith:
I placed a stopwatch in front of my scope's display.  Connected to a RF generator set to sweep from 5M - 100M.  Very small data set.  Norm trigger.  All processing turned off.  Camera set to 1000fps.   Recorded for 1sec.  Manually counted each screen update.  I measured a pathetic 30fps.  It's an 18 year old PC and based on how poorly it handles the X-Y music, not surprised. 

tautech:

--- Quote from: joeqsmith on April 30, 2024, 01:05:10 am ---I placed a stopwatch in front of my scope's display.  Connected to a RF generator set to sweep from 5M - 100M.  Very small data set.  Norm trigger.  All processing turned off.  Camera set to 1000fps.   Recorded for 1sec.  Manually counted each screen update.  I measured a pathetic 30fps.  It's an 18 year old PC and based on how poorly it handles the X-Y music, not surprised.

--- End quote ---
You may also been able to extract that info from the OS display refresh rate settings if you can stop the boot before the scope app loads.

joeqsmith:

--- Quote from: tautech on April 30, 2024, 01:10:44 am ---
--- Quote from: joeqsmith on April 30, 2024, 01:05:10 am ---I placed a stopwatch in front of my scope's display.  Connected to a RF generator set to sweep from 5M - 100M.  Very small data set.  Norm trigger.  All processing turned off.  Camera set to 1000fps.   Recorded for 1sec.  Manually counted each screen update.  I measured a pathetic 30fps.  It's an 18 year old PC and based on how poorly it handles the X-Y music, not surprised.

--- End quote ---
You may also been able to extract that info from the OS display refresh rate settings if you can stop the boot before the scope app loads.

--- End quote ---
Windows reports 60Hz refresh but they appear to refresh at half that. 

***
Just to add more detail, I can zoom in to say show only 25 data point on the screen, show dots rather than lines, it seems to top out at 30.   Member Wuerstchenhund had log ago suggest I swap out the CPU stating some significant performance gains.  I don't believe they ever provided me with any data and I have never tried to swap it out.  Maybe it would improve the refresh. 

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