VOLTCRAFT DOV series

[Kurt_!]

Hi Olex, Aldo

I need your help!
Hardware changes are already done, but I'm still having trouble with software changes.
I'm not very good at that, unfortunately.
I've already installed the editor on the oscilloscope.
But I wanted to make a backup copy!
It says DS01 not found...
Do I need to install root privileges first?

Hi,
Did you do this? https://www.eevblog.com/forum/testgear/voltcraft-dov-series/msg6284872/#msg6284872
You have to do that from the computer.

No, I haven't.
I kind of figured as much.

Okay, thanks.

[CeeJay]

I created a new Logo.bmp file and now a linux screen appears when the oscilloscope is powered on. When the oscilloscope app opens the new logo is correctly showed.
Why could be the reason because it happens?

I attach the image file compressed because it is not possible to upload .bmp files.

Did you use the chown command after copying the Logo.bmp file?
chown system:system /oem/Logo.bmp

[IC_Toaster]

I created a new Logo.bmp file and now a linux screen appears when the oscilloscope is powered on. When the oscilloscope app opens the new logo is correctly showed.
Why could be the reason because it happens?

I attach the image file compressed because it is not possible to upload .bmp files.

Did you use the chown command after copying the Logo.bmp file?
chown system:system /oem/Logo.bmp

Yes, I have just verify it and system is the owner.

-rwxrwx--- 1 system system 2457738 2026-09-11 21:07 Logo.bmp

[TomC]

I've been using a physical keyboard with my scope for a while but didn't know all of the Android keyboard shortcuts. Recently I found this website:

https://appt.org/en/docs/android/features/keyboard-access

Inspired by that information I tried all the shortcuts and made a little printable table with the ones that worked on my scope (see attachment).

[evava]

If I may, I’d like to return to the hardware modifications Martin showed here:
https://www.eevblog.com/forum/testgear/voltcraft-dov-series/msg6335724/#msg6335724
I thank him for that visual summary.

However, shouldn't there be a 4.7µF capacitor instead of a 470nF one at position R2437?
SL75 writes about this here, for example:
https://www.eevblog.com/forum/testgear/voltcraft-dov-series/msg6318140/#msg6318140

Or was it ultimately decided that 470nF is sufficient?

[Aldo22]

I noticed something today.
The RMS measurement on the DOV may be related to the horizontal resolution under certain circumstances.

Example: approx. 1 VRMS. at approx. 1 kHz.
At 1 ms/div, the measurement is quite accurate, but at 20 ms/div, for example, it’s too high (1.139 VRMS).
The Hantek shows a stable measurement with the same settings.

Is this also the case with your device?
Is this a phenomenon known from other manufacturers as well, or is it a DOV issue?

[sdroamt0]

...
Is this a phenomenon known from other manufacturers as well, or is it a DOV issue?
...

On DOV I see 25 MSa/s vs 2.5 MSa/s... if possible can you force the same sampling rate on DOV and repeat the measurements? (Yes I know.. on hantek too the sampling rate differs!)...
Whith different sampling rate and sinc interpolation I would expect different measurements...I'm wrong ?

[Martin72]

Hi,
Unfortunately, I can't reproduce it anymore, but:
When you look at the screenshots from the Hantek and the DOV, I see that the DVM on the DOV displays the same value as the measurement parameter on the scope, whereas on the Hantek, the voltage is displayed independently of the scope’s reading—because even on the Hantek, the reading shifted slightly upward when the time base was extended, while the DVM value remained the same.
The fact that the value changes at all when you adjust the time base has to do, among other things, with the measurement strategy used and the measure gate.
On larger oscilloscopes, the range in which the measurement is to be taken can be adjusted; otherwise, the entire horizontal range is typically used.
With longer time bases, there is also more noise because lower frequencies are picked up as well—this can affect the voltage measurement.

[Aldo22]

Unfortunately, I can't reproduce it anymore, but:
When you look at the screenshots from the Hantek and the DOV, I see that the DVM on the DOV displays the same value as the measurement parameter on the scope, whereas on the Hantek, the voltage is displayed independently of the scope’s reading—because even on the Hantek, the reading shifted slightly upward when the time base was extended, while the DVM value remained the same.
The fact that the value changes at all when you adjust the time base has to do, among other things, with the measurement strategy used and the measure gate.
..
With longer time bases, there is also more noise because lower frequencies are picked up as well—this can affect the voltage measurement.

OK, thanks.
Yes, with the Hantek, the DVM seems to be more independent of the normal automatic measurement.
But still, the deviation in the DOV is a bit extreme.

On larger oscilloscopes, the range in which the measurement is to be taken can be adjusted; otherwise, the entire horizontal range is typically used.

The Hantek has a measurement gate.

[Martin72]

That's remarkable.

[Aldo22]

That's remarkable.

Oh, I almost forgot: The DOV has that, too.
Measure -> Set -> Horizontal Range -> Cursor.

[Martin72]

OK, times have obviously changed.

[Kurt_!]

Unfortunately, I'm not that far yet either.
Can anyone tell me what kind of error has crept in? Image

[Aldo22]

Unfortunately, I'm not that far yet either.
Can anyone tell me what kind of error has crept in? Image

That's a warning, not an error.
Just ignore it.

[Frederik]

Hi,
If some of your guys are looking into optimizing the fan, then it’ll very useful to know the CPU temperature while the oscilloscope software runs. The following script, running from the ADB shell, shows the current CPU temperature. Divide the reading with 1000.

while true; do cat /sys/class/thermal/thermal_zone0/temp; sleep 3; done

I used this to make my DOV almost silent.  I add an 80mm low noise fan, mounted inside the back cover with analog speed control. The CPU temperature maxes at 75 degrees Celsius on heavy load on my unit.

/Frederik

[Kurt_!]

Aldo, Olex... Please help.

Unfortunately, I had to abort due to a background issue (visit)
Before entering the password.
The next day...
Now I'm having a problem trying again!
"Damon not running; starting now at tcp:5037"
No connection....
Is the problem with the PC or the oscilloscope?

[Martin72]

At what point in the instructions are you stuck right now?

[Kurt_!]

$ adb devices -l

It can't find the port...

[Martin72]

Oh, that's not exactly far...


I don't have anything to do with all that software stuff, but I still managed to figure it out on my own, including the boot.txt change.
If I understand this correctly, you use the terminal program on the Scope to turn the Scope into a kind of USB drive that you can then access externally via the PC.
I’d noticed that back then, too—the DOV was already connected to the PC via USB, so the PC would play a system sound when I finished that part on the Scope.
That’s why it doesn’t quite add up with the TCP and daemon messages you’re seeing.
But like I said, me and software… I’m more of a hard guy.

[Kurt_!]

After this error message, ADB searches for TCP port 5037.
Unfortunately, ADB can no longer find it...
On the PC, it is displayed in the taskbar under USB devices as "MTP".

I'll try again tomorrow.
I probably shouldn't have given up!

[CeeJay]

You have to do this command on the oscilloscope terminal again:

setprop sys.usb.config mtp,adb

The adb setting will not be saved. So you have to do it every time before connecting via adb with your PC.

[Kurt_!]

I would have already done that.
I'll try resetting it to "None" and then start again... swap the cables... then we'll see... Thanks

[Kurt_!]

Unfortunately, no luck!
Have you tried a factory reset?

Last option...
 

[TomC]

I noticed something today.
The RMS measurement on the DOV may be related to the horizontal resolution under certain circumstances.

Example: approx. 1 VRMS. at approx. 1 kHz.
At 1 ms/div, the measurement is quite accurate, but at 20 ms/div, for example, it’s too high (1.139 VRMS).
The Hantek shows a stable measurement with the same settings.

Is this also the case with your device?
Is this a phenomenon known from other manufacturers as well, or is it a DOV issue?

Same behavior here. I noticed that the memory depth is 4Kpt on the Hantek, but it's 1M on the DOV for the same test. If you change the depth on the DOV to 1K the VRMS is more accurate (see attachment 1). However, this causes some aliasing due to under sampling (see attachment 2). I think there is also some under sampling in your Hantek screenshot but not as severe.

[Frederik]

After this error message, ADB searches for TCP port 5037.
Unfortunately, ADB can no longer find it...
On the PC, it is displayed in the taskbar under USB devices as "MTP".

I'll try again tomorrow.
I probably shouldn't have given up!

Kurt, I think the problem lies on your PC. Do you have another android device to test it with you PC, if not Try run adb from linux or MAC or something else. I had the same problem on my PC when running Windows 11, it stop working and I couldn't find the reason why, so I just boot linux and adb work as it should. it looks like that the MTP protocol take the USB port and stops adb.