Acquisition mode "average" showing different waveform on the second channel.

[Aldo22]

I noticed something strange with my new Hantek yesterday.
The situation is this: I have 2 active channels and the second channel has a slightly higher frequency than the first (+0.1Hz), like if you want to create a slowly rotating Lissajous figure.
The trigger is on Ch1 (yellow).

All good, in "normal" acquire mode.
But if I switch to "average" and set the "average count" a little higher to e.g. 32, then the moving square becomes a trapezoid on screen.
However, as soon as I press "Stop" or want to take a screenshot, it becomes a square again.
That's why there are photos in the attachment and not screenshots.

Is this normal or a Hantek "specialty"?

Thank you!

[2N3055]

In short it is artefact of how Averaging acquisition work.
Something similar would happen on all scopes with Average acquisition.
It is sometimes useful, but very limited mode, that needs to be applied in specific way to work well.

Try reading in manual on how Average works... If Hantek manual does not explain it use any manual from Keysight, Tek, Siglent, R&S ... They all work similarly

If you still have problem understanding come back here and we'll try to explain it in more detail..

[Aldo22]

The Hantek manual does not go much into depth:

Average: In this acquisition mode, the oscilloscope acquires several waveform, averages them, and displays the resulting
waveform. You can use this mode to reduce random noise.

High Resolution (HR): This mode uses a kind of ultra-sample technique to average the neighboring points of the sample
waveform to reduce the random noise on the input signal and generate much smoother waveform on the screen. This is generally
used when the sample rate of the digital converter is higher than the storage rate of the acquisition memory.

Note: "Average" and "HR" modes use different averaging methods. The former uses "Multi-sample Average" and the latter
uses "Single Sample Average".

But it is described quite well here:

This mode should only be used under certain circumstances or you could get misinformation on the screen.
Averaging acquisition mode should be used only with periodic signals and with a stable oscilloscope trigger.
If the signal is aperiodic, the displayed signal will not be valid data—just a conglomeration of changing signals over time.
If there’s a glitch in the signal, it will be hidden by the continuous averaging.

Thank you!

[2N3055]

The Hantek manual does not go much into depth:

Average: In this acquisition mode, the oscilloscope acquires several waveform, averages them, and displays the resulting
waveform. You can use this mode to reduce random noise.

High Resolution (HR): This mode uses a kind of ultra-sample technique to average the neighboring points of the sample
waveform to reduce the random noise on the input signal and generate much smoother waveform on the screen. This is generally
used when the sample rate of the digital converter is higher than the storage rate of the acquisition memory.

Note: "Average" and "HR" modes use different averaging methods. The former uses "Multi-sample Average" and the latter
uses "Single Sample Average".

But it is described quite well here:

This mode should only be used under certain circumstances or you could get misinformation on the screen.
Averaging acquisition mode should be used only with periodic signals and with a stable oscilloscope trigger.
If the signal is aperiodic, the displayed signal will not be valid data—just a conglomeration of changing signals over time.
If there’s a glitch in the signal, it will be hidden by the continuous averaging.

Thank you!

You are welcome.

As you know now, second channel was not correlated  with triggered channel. So "sampling point" was moving on 2nd channel on different places with time and it was averaged like that.
Play with a frequency a bit, you can get all kinds of funny shapes...

[Aldo22]

As you know now, second channel was not correlated  with triggered channel. So "sampling point" was moving on 2nd channel on different places with time and it was averaged like that.
Play with a frequency a bit, you can get all kinds of funny shapes...

Yes!

The other thing to note here is that the Hantek DSO2000 never shows an "average" screen when you press "Stop" or take a screenshot.
I haven't checked the other modes, but with "average" it always seems to save a "normal" screen.
So if you turn on "average" to get a smooth waveform on a screenshot, you're out of luck.
It does however save the "ghost lines" in "persist" mode.

Thank you!