Ho-Ro
commented
3 years ago Stephen, the behaviour of the scope is exactly what one would expect from a DSO (digital storage scope). A DSO works like this: capture the input signal into a buffer (in your case at least for 200 ms/div * 10 div = 2 s) and when the buffer is filled refresh the screen with the new buffer content. This would give one refresh every two seconds for a free-running signal. But to get a standing display you want to trigger. The Hantek6022 don't have any hardware trigger, so triggering is done completely in SW. Therefore the program samples into a bigger buffer that equates twice the screen size, searches for a sufficient trigger point and displays the corresponding section of the buffer. This leads to a refresh every 4 seconds. As you wrote correctly the refresh rate increases when sampling faster.
Expected behavior The screen should reflect the signal changes instantly (or to be perceived as such).
If you want to follow real slow signals you should use the Roll trigger mode that is available for slow timebase >= 200 ms/div. Otherwise the screen refresh at e.g. 10 s/div would take 200 s!
the minimal time between captured frames ...
is used to reduce high CPU load - especially on small systems like RasPi - at high sample rates (>10MS/s).
stephenwang5
The main signal screen takes ~1 sec to fresh if I change the timebase or if the signal itself changes. I encountered this when probing capacitor discharge on a 555 timer (waveform shown bellow). I would understand if this is some hardware limitation but my CPU usage appears very low and to my surprise it appears to refresh more quickly the smaller timebase I used. I've tried to adjust the minimal time between captured frames but to no avail.
To Reproduce I left most of the settings on default and all the other settings are shown in the screenshot bellow.
Expected behavior The screen should reflect the signal changes instantly (or to be perceived as such).
Screenshots Here's the waveform I'm inspecting
Computer environment:
Scope device (please complete the following information):
Additional context Program started using the
.desktopgenerated when installing (executed without any additional flags)