New 2ch pocket DSO+SG - Zeeweii DSO2512G

[Fungus]

That is not my point.
I'm wondering why the match is so amazingly accurate for the square wave but not for the sine wave under exactly the same conditions.

Probably just luck. Two wrongs making a right.

[Aldo22]

That is not my point.
I'm wondering why the match is so amazingly accurate for the square wave but not for the sine wave under exactly the same conditions.

Probably just luck. Two wrongs making a right.

Could be, but the AN870 True-RMS should actually be in its comfort zone at 500Hz.
Do you think the +-(0.3% +3) AC voltage accuracy is a lie?

EDIT: https://chinese-electronics-products-tested.blogspot.com/p/aneng-an870-multimeter-tested.html

[JeremyC]

Could be, but the AN870 True-RMS should actually be in its comfort zone at 500Hz.
Do you think the +-(0.3% +3) AC voltage accuracy is a lie?

Your DSO2512G scope has 8 bit ADC, it means in theory 256 quantization points. In reality effective number of bits (ENOB) is in 5 – 7 bits range.
I’m guessing your scope is in the 5 – 6 bits range. In your example the scope uses 500mV measure range and measured signal will be quantize in 14.3mV 15.6 mV steps.
   500mV / (2^5) = 14.3mV = 15.6mV
Delta between your ANENG and the scope is ~20mV what makes sense when you add ANENG’s and the scope’s inaccuracy into this equation.

Edit: I corrected typo.

[Aldo22]

Your DSO2512G scope has 8 bit ADC, it means in theory 256 quantization points. In reality effective number of bits (ENOB) is in 5 – 7 bits range.
I’m guessing your scope is in the 5 – 6 bits range. In your example the scope uses 500mV measure range and measured signal will be quantize in 14.3mV steps.
   500mV / (2^5) = 15.6mV
Delta between your ANENG and the scope is ~20mV what makes sense when you add ANENG’s and the scope’s inaccuracy into this equation.

Thanks, that sounds like a reasonable explanation of the difference.

However, then again I do not understand at all the measurement here.

See excerpt in the attachment.

That would be more than 7% error at 1Vrms/1kHz square wave for the AN870.
The measurement can't be right, can it?
In any case, that is not what I see.

[ptluis]

I just wanted to check how well the DSO2512G and the An870 match on the RMS measurement.
While for a square wave (500Hz, 50%, ~1V) the agreement is quite exact (1.00V vs. 1.0017V), it is not so exact for a sine wave (0.721V vs 0.7413V).
Why is this and which device measures more correctly?

Thank you!

Hi did you use coaxial or probes on your tests?

[Aldo22]

Hi did you use coaxial or probes on your tests?

Hi ptluis

I used the probes in 1x mode.
I had to connect the multimeter at the same time and that has no BNC or SMA input.
We are talking about 500Hz.

[ptluis]

Hi did you use coaxial or probes on your tests?

Hi ptluis

I used the probes in 1x mode.
I had to connect the multimeter at the same time and that has no BNC or SMA input.
We are talking about 500Hz.

Thanks, I want to replicate the test to see what values i get on my devices  I'll post here the results.

[ptluis]

Hi did you use coaxial or probes on your tests?

Hi ptluis

I used the probes in 1x mode.
I had to connect the multimeter at the same time and that has no BNC or SMA input.
We are talking about 500Hz.

My results:

Frequency: 500Hz, 1Vpp, Sine and Square wave, RMS values
I use the same 200MHz Probe PP215 across devices at 1X

UT61E (Connected directly to FG output)
Sine wave: 351.7mV
Square wave: 497.6mV

Siglent SDS1202X-E and SDS1104X-E (Aquire mode Normal)
Sine wave: 351.8mV and 351.9mV
Square wave: 498mV and 498.1mV

DSO2512G (Firmware 1.2.8.C+)
Sine wave: 349mV
Square wave: 491mV

DPOX180H (With the over compensated defect in AC coupling)
Sine wave: 332mV
Square wave: 473mV

[Aldo22]

Thanks for testing ptluis!
So according to your measurements it can be said that the DSO2512G is within its specifications and provides sufficiently accurate values for a cheap oscilloscope?

As you may have seen in the other thread, I got an FY3200S.
Now that's not a reference for accuracy either, but at least it's another "opinion".
It is set to 500Hz and 5V in the attached pictures.

In the first picture you can see that all devices are accurate when measuring frequency @500Hz.

In the second picture (sine wave) the Zeeweii measures 4.94V PkPk (1.71V VRMS) and the An870 measures 1.768 VRMS. The An870 is exactly as expected (5V x 0.3536), assuming the FY3200S can be trusted, which I have my doubts about.

In the third image (square wave), the Zeeweii still measures 4.94V PkPk (2.42 VRMS) and the An870 measures 2.419 VRMS, exactly the same as the Zeeweii.

Sooo, all three devices are of course no high-precision instruments, but they agree quite well.
I just don't quite understand how the Zeewei can measure the exact same PkPk twice  (which is slightly less than that given by FY3200S),  but only agree with the An870 on the square wave RMS.

[ptluis]

Thanks for testing ptluis!
So according to your measurements it can be said that the DSO2512G is within its specifications and provides sufficiently accurate values for a cheap oscilloscope?

As you may have seen in the other thread, I got an FY3200S.
Now that's not a reference for accuracy either, but at least it's another "opinion".
It is set to 500Hz and 5V in the attached pictures.

In the first picture you can see that all devices are accurate when measuring frequency @500Hz.

In the second picture (sine wave) the Zeeweii measures 4.94V PkPk (1.71V VRMS) and the An870 measures 1.768 VRMS. The An870 is exactly as expected (5V x 0.3536), assuming the FY3200S can be trusted, which I have my doubts about.

In the third image (square wave), the Zeeweii still measures 4.94V PkPk (2.42 VRMS) and the An870 measures 2.419 VRMS, exactly the same as the Zeeweii.

Sooo, all three devices are of course no high-precision instruments, but they agree quite well.
I just don't quite understand how the Zeewei can measure the exact same PkPk twice  (which is slightly less than that given by FY3200S),  but only agree with the An870 on the square wave RMS.

I use Uni-t UTG962 FG, I calibrated my zeeweii after firmware upgrade, after firmware upgrade the values zeeweii display for RMS need to be calibrated through a special menu option using a function generator, in my case i use the Uni-t
After new calibration RMS display values won't be like yours like 721mV but something like 349mV for example (didn't do the math)

[Aldo22]

I use Uni-t UTG962 FG, I calibrated my zeeweii after firmware upgrade, after firmware upgrade the values zeeweii display for RMS need to be calibrated through a special menu option using a function generator, in my case i use the Uni-t
After new calibration RMS display values won't be like yours like 721mV but something like 349mV for example (didn't do the math)

Is there any news on this?
I would also like to have this firmware update (calibration) on my DSO2512G.
The zoom feature would be less important to me.

[ptluis]

I use Uni-t UTG962 FG, I calibrated my zeeweii after firmware upgrade, after firmware upgrade the values zeeweii display for RMS need to be calibrated through a special menu option using a function generator, in my case i use the Uni-t
After new calibration RMS display values won't be like yours like 721mV but something like 349mV for example (didn't do the math)

Is there any news on this?
I would also like to have this firmware update (calibration) on my DSO2512G.
The zoom feature would be less important to me.

No news yet, this week I post the firmware and instructions for those who want to try it. Anyway neither I or Zeeweii assume any RESPONSABILITY for bricked scopes.  Do it at your own risk. It's a simple process but certify you have a good usb-c data cable. ONLY FOR FIRMWARE 1.2.8C devices!

[Aldo22]

No news yet, this week I post the firmware and instructions for those who want to try it. Anyway neither I or Zeeweii assume any RESPONSABILITY for bricked scopes.  Do it at your own risk. It's a simple process but certify you have a good usb-c data cable. ONLY FOR FIRMWARE 1.2.8C devices!

Thanks!
Are you sure it's for 1.2.8C?
That would be exactly my version.

[ptluis]

No news yet, this week I post the firmware and instructions for those who want to try it. Anyway neither I or Zeeweii assume any RESPONSABILITY for bricked scopes.  Do it at your own risk. It's a simple process but certify you have a good usb-c data cable. ONLY FOR FIRMWARE 1.2.8C devices!

Thanks!
Are you sure it's for 1.2.8C?
That would be exactly my version.

That's the version I had on mine before updating. A few posts back I talk about the version and board revision. after upgrading you will get v1.2.8C+ (plus version)

[ptluis]

I received a message from zeeweii today, there will be no more firmware updates for this oscilloscope.  It seems that they gave up on improving it and adopted the model of all other sellers of this type of product, launching new products with 2 or 3 suggestions given by users and making a profit.  In any case, it continues to be the best of its kind in my opinion.

Aldo22 I will post the 1.2.8C and 1.2.8C+ firmwares tomorrow or the day after on this forum for you or others who wish to try, or keep a backup of the original 1.2.8C

[Aldo22]

I received a message from zeeweii today, there will be no more firmware updates for this oscilloscope.  It seems that they gave up on improving it and adopted the model of all other sellers of this type of product, launching new products with 2 or 3 suggestions given by users and making a profit.  In any case, it continues to be the best of its kind in my opinion.

Aldo22 I will post the 1.2.8C and 1.2.8C+ firmwares tomorrow or the day after on this forum for you or others who wish to try, or keep a backup of the original 1.2.8C

Hi ptluis

I must say that I actually never expected a firmware update from Zeeweii.
The firmware doesn't have any serious bugs as far as I know and you can't really expect a feature upgrade for this price, especially since there are also different hardware versions of this device.

This may also open up "a can of worms" (bricked devices, mismatched FW-HW, support requests -> unhappy customers).
They would probably rather avoid that.

Therefore I am very surprised that there is a 1.2.8C+ and would like to try it out especially because of the calibration option.

Thank you!

[ptluis]

\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\

!!! I won't assume any responsibility if you brick your scope for whatever reason!!
!! ZEEWEEI WON'T HELP YOU EITHER!!

If you don't trust me, DON'T DOWNLOAD! GO DRINK A BEER!
If you are happy with your scope the way it is, DON'T DOWNLOAD! GO EAT A BURGER AND TWO BEERS!
IF it's to complicated, stay still and then GO EAT ANOTHER BURGER AND THREE BEERS!
If OTHER reason, DRINK FOUR BEERS!!! AND BE HAPPY!!!!



\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\




----===!!! Zeeweei DSO2512g firmware upgrade. ONLY FOR SCOPES WITH ORIGINAL FIRMWARE V1.2.8C !!!===---

If your scope original firmware is NOT v1.2.8C DO NOT DOWNLOAD!!! OR TRY UPGRADING!!
YOU WILL BRICK YOUR SCOPE IF YOU DO IT!! YOU HAVE BEEN WARNED!!! IT'S YOUR RESPONSIBILITY!
Stop here and GO DRINK 5 BEERS!!!!

----=============================================================================----


!!!! Warning!!!! If you don't have a good and stable function generator stop here! and don't Upgrade firmware !!!!!




If your scope original firmware is v1.2.8C and you have a good and stable function generator, then continue reading



Upgrade_dso2512g.zip file contents:

- dso2512g_v1.2.8C.bin  (Original firmware of scope)

- dso2512g_v1.2.8C+.bin (Firmware Upgrade, Plus version)

- log.txt (how to use calibration and zoom features - Original instructions )

- Upgrade steps128c.txt  (How to upgrade - original instructions)


After downloading the file Upgrade_dso2512g.zip always run it through a virus scanner.
If you find other files besides those indicated above, delete it and find the original one posted by me on this forum.

---------------------------------------------------------------------------------------


<REQUIREMENTS:>

1. A good USB-C DATA cable!!! I had problems with the original cable supplied by Zeeweei, so beware!
2. Windows 7, 8, 10, 11 (don't ask me about MAC, I don't use it)
3. The Scope with the Battery fully charged
4. Function generator to calibrate the scope 2.5Vpp 1KHz sine waveform

!!!! Warning again!!!! If you don't have a good and stable function generator stop here! and don't Upgrade firmware!!!!!



<PROCEDURE:>

1. With the scope in OFF state, press and hold [mv] and [Power] buttons at same time to start scope in "upgrade mode"
 
2. After a few seconds, the firmware upgrade picture (or a menu) appears on the screen, depending how old is your unit.

3. Connect scope USB-C to computer USB port using a GOOD USB-C DATA cable.

4. A Udisk appears on the computer (like a USB flash drive).

5. Copy dso2512g_v1.2.8C+.bin to the Udisk.

6. Disconnect Udisk from computer using "Safely Remove Hardware icon" on the taskbar! (don't disconnect USB-C cable without this step!)

7. Disconnect USB-C cable from computer and scope (**very important**, don't leave them connected!!).

8. Click the [Power] button and then click the [OK] button (on some scopes a menu appears with the option to shutdown)

9. Shut down and restart.

10. Scope will show upgrading process. When done, restart or follow the instructions on Screen.

11. THEN you will need a function generator to calibrate the scope, follow the instructions


Done!
Your firmware is upgraded to v1.2.8C+  (plus version)


NEW FEATURES:
-------------

< ZOOM MODE >:

 PRESS "s" key for 2 secs to enter this mode. To exit press again for 2 secs
 Zoom is not supported when roll mode or cursor is on
 Always exit zoom mode before shutdown scope, there's a bug that resets some scope settings

< CALIBRATION >:

Entering this mode could be a little tricky, but after you understand it, it's easy
Refer to file log.txt for instructions
In this file CH1CH2 means you select the desired channel for calibration
You can enter this mode whenever you want

The plus firmware allows you to enter this hidden function where you can manually adjust the values of the Vpp and Mean to correct the displayed values if they are out of specs. That's how they calibrate measurements on this scope

It's really useful, my scopes where some 0.3V to 0.5V off in Vpp measurements


NOTE:
RMS measurements will show different, for ex: Before upgrade 1Vpp=740mV RMS, after upgrade 1Vpp=380mV RMS (no math involved by me at those examples) Not true, ignore this. It was based on other user post that won't match commented text. The RMS values are correct.

Test Frequency: 500Hz, 1Vpp, Sine and Square wave, RMS values

DSO2512G (Firmware 1.2.8.C+)
Sine wave: 349mV RMS
Square wave: 491mV RMS



BUGS:

ZOOM MODE:
1. if you press AUTO while in ZOOM MODE, mostly above 500KHz, the scope when zooming out (pressing "s" key), freezes and then crashes). It will restart OK.
Solution: do not press AUTO while in ZOOM MODE

2. If you shutdown scope in zoom mode, there's a bug that resets some scope settings
Solution: Always exit zoom mode before shutdown scope


And that's it!


Sorry for any mistakes but I'm not English native

[Aldo22]

Thank you for sharing this with us! Much appreciated.  

I won't rush anything, because first I want to grasp a few more things, especially I need to see if I can provide a reliable VPkPk reference at all.

E.g. you say "RMS measurements will show different, for ex: Before upgrade 1Vpp=740mV RMS, after upgrade 1Vpp=380mV RMS"

I don't see that with my "old" version (->image).
Was your Zeeweii maybe in DC mode and the Signal had a DC offset? 

But I must also say that I don't quite understand the relationship between RMS and PkPk within the Zeeweii and to the An870 (my best reference).

For example these measurements at 1kHz:

The signal comes from FY3224S (amplitude is not precise, I think) measured with AN870 and Zeeweii.
Trying to get as close as possible to 1V with the FY3224S steps.

Trying to take the Zeeweii as Reference for 1 VPkPk:

Code: [Select]

Zeeweii  : 0.997 VPkPk / 0.340 Vrms
An870   : 0.3644 Vrms
FY3224S: 1.05 V

Trying to take the An870 as Reference for 0.3536 Vrms (Should be theoretically correct at 1 V sine, right?)

Code: [Select]

An870   : 0.3546 Vrms
Zeeweii  : 0.981 VPkPk / 0.331 Vrms
FY3224S: 1.02 V

Internal Generator of the Zeeweii at 2.5 V/1kHz

Code: [Select]

Zeewei: 2.51 VPkPk / 0.859 Vrms
An870 : 0.8909 Vrms

So: I have no problem with the Zeeweii being slightly off from the AN870, that's why we want to adjust it.
What I don't understand is why the Zeeweii calculates the way it does internally.
1VPkPk sine should correspond to 0.3536 Vrms and not 0.340 Vrms.



Could someone shed some light on this?
I would like to understand this first, otherwise it doesn't make sense since I only have the AN870 as a Vrms reference and no VPkPk measurement with more precision.

Thank you!

[Aldo22]

I have more questions and thoughts about this.
@ptluis: I don't expect you to answer all my questions.
But if you feel like it and have time and know the answer, of course I'm happy. 

1. you mention Windows and Mac as PC for the update. Was it said by Zeeweii that it doesn't work on Linux? I use Linux and have no problem with downloading screenshots from the Zeeweii, for example.

2. is one forced to calibrate/adjust after the FW update or does the measurement work as before?

3. how is the automatic calibration via menu related to this manual calibration?

4. is point 5 of the update procedure something that makes sense in the context of the update menu or is it meant "blindly"? ("Click the "Power" button, and then click the "ok" button.")

Thank you!

[ptluis]

I have more questions and thoughts about this.
@ptluis: I don't expect you to answer all my questions.
But if you feel like it and have time and know the answer, of course I'm happy. 

1. you mention Windows and Mac as PC for the update. Was it said by Zeeweii that it doesn't work on Linux? I use Linux and have no problem with downloading screenshots from the Zeeweii, for example.

No! I said can't help with MAC because I don't use Macintosh. I did it in Windows OS. I don't use linux but I suppose the principle is to connect the scope to the computer, mount it  (I think in linux is how you do it) to be able to copy the bin file into Udisk of the scope. Then Unmount it, remove cable and boot the scope so that it will detect a new firmware and update it by himself. BUT you know better then I how to operate linux. I don't use linux for many years so I'm outdated.


2. is one forced to calibrate/adjust after the FW update or does the measurement work as before?

From what I recall, after the scope updates the firmware, when he boots he will enter calibration mode automatically, but I remember it show the previous values. BUT I always did the calibration as asked, so I supposed it will keep the old values, can´t say for sure.

3. how is the automatic calibration via menu related to this manual calibration?
Automatic calibration is part of the upgrade procedure, after the scope updates the firmware it enters the calibration mode automatically. You can always enter this mode manually

4. is point 5 of the update procedure something that makes sense in the context of the update menu or is it meant "blindly"? ("Click the "Power" button, and then click the "ok" button.")

This procedure is necessary if your scope doesn't display the update menu, it happened in one scope from the 5 I updated, maybe that one was a clone? I don't know but it function like the others.

If you don't feel confident and are happy how your scope operates, honestly you shouldn't do it. Like I said you need to have a stable FG so that calibration is done properly .

Thank you!

[ptluis]

E.g. you say "RMS measurements will show different, for ex: Before upgrade 1Vpp=740mV RMS, after upgrade 1Vpp=380mV RMS"

I don't see that with my "old" version (->image).
Was your Zeeweii maybe in DC mode and the Signal had a DC offset? 

I based my comment in your previous posted photo.
"Test, 1Vpp, 500Hz sine waveform" display on your device 721mV RMS
There's something wrong with this image, you say you test it with 1Vpp but if we count the division you apply 2.1Vpp



My devices display:
Frequency: 500Hz, 1Vpp, Sine waveform, RMS values
I use the same 200MHz Probe PP215 across devices at 1X

UT61E (Connected directly to FG output)
Sine wave: 351.7mV

Siglent SDS1202X-E and SDS1104X-E (Aquire mode Normal)
Sine wave: 351.8mV and 351.9mV

DSO2512G (Firmware 1.2.8.C+)
Sine wave: 349mV

DPOX180H (With the over compensated defect in AC coupling)
Sine wave: 332mV

[ptluis]

I corrected the NOTE text about RMS on my firmware posted before. Sorry for that.

[Aldo22]

Hi ptluis.

I based my comment in your previous posted photo.
"Test, 1Vpp, 500Hz sine waveform" display on your device 721mV RMS
There's something wrong with this image, you say you test it with 1Vpp but if we count the division you apply 2.1Vpp

You mean this comment?

Yes, sorry for the confusion, but I didn't say Vpp.

Since the An870 can only measure Vrms and not Vpp, all the readings were in Vrms. Vpp measurement was turned off in the zeeweii.
It was set to ~1 Vrms square wave according to AN870 (first photo).
For the sine wave, I just changed the waveform and didn't change the volts.

But actually these pictures were not about the absolute amplitude but an example for the Vrms difference or agreement between the devices.

I'll try to be more precise next time. 

[Aldo22]

Thank you for the answers! 

3. how is the automatic calibration via menu related to this manual calibration?
Automatic calibration is part of the upgrade procedure, after the scope updates the firmware it enters the calibration mode automatically. You can always enter this mode manually

I would be interested to know if it affects the same parameters. Does a manual calibration override the automatic calibration and vice versa?
Have you ever tried a downgrade to the original version?
Will an automatic calibration make everything normal again, or were parameters manually changed that I can no longer reach with the original version?

If you don't feel confident and are happy how your scope operates, honestly you shouldn't do it. Like I said you need to have a stable FG so that calibration is done properly .

I actually think that a FY3224S would be sufficient.
It is not very accurate to adjust, but it generates a stable 1 kHz sine wave at ~2.5 Vpp.
I can adjust the amplitude (mV) using the An870.
The feeltech AWGs can also be adjusted, but I'm not sure that makes much sense.


I would like to try it, but actually my DSO2512G is not that far off on the measurements. I'm not sure if I can even get it to be more accurate.
And so I'm still hesitant...

Thank you.

[ptluis]

Hi ptluis.

Yes, sorry for the confusion, but I didn't say Vpp.

Oops! my mistake  I'm replying on my cell phone, and doing a lot of Vpp work and my brain is formatted for Vpp 
Everything is clarified now.
Compare your results with my results. As you see Zeeweii is not to apart from the Siglents scopes